7157

TP53

LFS1|P53|TRP53;tumor protein p53;TP53;tumor protein p53

antigen NY-CO-13|cellular tumor antigen p53|p53 tumor suppressor|phosphoprotein p53|transformation-related protein 53|tumor suppressor TP53

17p13.1

protein-coding

BACKGROUND: The past decade has witnessed a growing frequency of therapy-relatedsecondary tumors. The authors studied nine children with secondary malignancies.The primary tumors were bilateral retinoblastoma, neuroblastoma, brain tumor, Wilms' tumor, colon adenocarcinoma, and Hodgkin's disease. The secondary tumors were osteosarcoma at the site of previous radiotherapy, myelodysplastic syndrome, acute myelocytic leukemia, glioblastoma, thyroid carcinoma, and B-cell lymphoma.METHODS: DNA was extracted from the primary and secondary tumors and analyzed for genetic alterations in the p53 gene and in 7 separate microsatellites. RESULTS: The authors found p53 mutations in 7 patients, loss of heterozygosity in 1 patient, and both mutation and loss of heterozygosity in 1 patient. mutations were demonstrated in the primary tumors only in two patients and in the secondary tumors only in three patients. Two patients had a mutation in both the primary and the secondary tumor; in both patients the two mutations were in different exons. Microsatellite instability (MIN) was identified in five to seven loci in the secondary tumors of ALL patients. CONCLUSIONS: The observed MIN is compatible with the presence of a mutator phenotype that predisposes these children to the development of secondary malignancies.

PURPOSE: Apoptosis plays a crucial role in normal development and mediates tumorresponse to chemotherapy. This study investigated the pattern of apoptotic gene expression in brain tumor tissue specimens and cell lines. MATERIALS AND METHODS: BCL2, BCLXL, BCLXS, and BAX transcripts were amplified using reverse transcriptase polymerase chain reaction in 7 high-grade gliomas (HGGs), 7 ependymomas, and 6 cell lines (2 glioblastomas, 3 medulloblastomas, and 1 supratentorial-primitive neuroectodermal tumor [PNET]). Immunohistochemical staining for BCL2, BCLX, BAX, and p53 was performed in 7 pediatric low-grade gliomas (LGGs) and 7 pediatric HGGs. RESULTS: Six of seven gliomas, ALL ependymomas, and ALL glioblastoma and medulloblastoma cell lines expressed BCLXLand BAX. BCL2 expression was only detected in the supratentorial PNET line PFSK.BCLXS was absent in ALL tumors. By immunohistochemistry, no glial tumors stainedpositively for BCL2. Similar BAX and BCLX protein expression was observed in LGGand HGG. Three of five glioblastomas showed significant p53 expression. CONCLUSIONS: Coexpression of proapoptotic and antiapoptotic genes in human braintumors supports the hypothesis that the relative expression of competing genes determines apoptotic threshold.

The molecular genetic characterization of Wilms' tumor has played a prominent role in advancing our knowledge of the genetic aspects underlying the development of cancer in general. Unlike the genetic mechanism leading to the development ofretinoblastoma, an embryonal tumor of childhood affecting the retina, which onlyrequires the inactivation of one single gene, the biological pathways leading tothe development of Wilms' tumor are complex and likely involve several genetic loci. These include two genes on chromosome 11p; one on chromosome 11p13 (the Wilms' tumor suppressor gene WT1) and the other on chromosome 11p15 (the putative Wilms' tumor suppressor gene WT2). In addition to these two genes, loci at 1p, 7p, 16q, 17p (the p53 tumor suppressor gene), and 19q (the putative familial Wilms' tumor gene FWT2) are also believed to harbor genes involved in the biology of Wilms' tumor. Herein these loci are reviewed and their clinical significance is summarized.

BACKGROUND: Follicular lymphoma in childhood is rare. The authors present four unusual primary follicular lymphomas of the testis in children. METHODS: tumor tissue was evaluated using light microscopy, immunohistochemistry, flow cytometry, and polymerase chain reaction (PCR) for immunoglobulin heavy chain (IgH) and bcl-2 gene rearrangements. Southern blot and immunohistochemical analyses were used to detect bcl-6 gene rearrangements and protein expression, respectively. RESULTS: Four young boys ranging in age from 3 to 10 years were diagnosed with Stage IE follicular large cell lymphoma (Grade 3). A B-cell phenotype was documented in ALL four cases; monoclonality was confirmed in threecases by demonstration of light chain restriction or clonal IgH gene rearrangement. None of the lymphomas expressed Bcl-2 or p53 protein, and bcl-2 gene rearrangements were not found in the three lymphomas studied. In contrast, Bcl-6 protein was expressed by ALL three lymphomas studied, and a bcl-6 gene rearrangement was detected in the one case analyzed by Southern blot. ALL four boys were treated by orchiectomy and combination chemotherapy and are alive withno evidence of disease 18-44 months following their initial diagnoses. CONCLUSIONS: Follicular lymphomas may rarely occur as primary testicular tumors in prepubertal boys and, when localized, appear to be associated with a favorable prognosis. In contrast to follicular lymphoma in adults, pediatric follicular lymphomas of the testis are usually of large cell type (Grade 3) and lack bcl-2 or p53 abnormalities. The identification, in one case, of a bcl-6 gene rearrangement suggests an alternate molecular pathogenesis for pediatric follicular lymphoma.

A non-tumorigenic human thyroid epithelial cell line (HTori-3) has been transformed into tumorigenic cells by exposure in vitro to alpha particles or gamma-radiation. These transformants were tumorigenic in athymic nude mice and tumors were transplantable into other nude mice. To further characterize processes involved in neoplastic progression, the tumor cell lines derived from these radiation-induced primary tumors were screened for mutations in the p53 tumor suppressor gene. p53 mutation was detected by single-strand conformation polymorphism (SSCP) analysis of exons 5 to 8 inclusive. mutations detected by SSCP analysis were confirmed by sequencing. mutations were detected in ALL four exons analysed, although there was no correlation between dose, LET or mutation position or frequency. mutations in p53 exons 6 and 7 have been reported in the childhood papillary thyroid carcinomas in Belarus presumably as a result of radioiodine fall-out. Similarly here, p53 mutations are induced experimentally during the development of human thyroid tumors generated by irradiation of a human thyroid epithelial cell line in vitro.#CI- Copyright 1999 Elsevier Science B.V.

As dermatologists, we have ALL been active in educating patients about sun awareness and sun protection. This is even more important for children, as childhood exposure to ultraviolet light is a significant risk for both melanoma and nonmelanoma skin cancers. The importance of an educational approach in appropriate sun awareness in childhood is further underscored by the recent findings by Rivers et al., in the Vancouver Moles Cohort study, presented at the1999 American Academy of Dermatology meeting. In a placebo-controlled trial, thefindings of Rivers et al. clearly demonstrated that the use of sunscreens can significantly decrease the formation of nevae in children, providing further evidence to support sun awareness education initiatives. The lead article by Gooderham and Guenther in the Basic and Clinical Sciences section evaluates the effectiveness of a particular sun awareness program, and gives valuable insightsinto how more effective approaches may be used in the future. In addition to ultraviolet light playing a causal role in cutaneous malignancies, it is known to induce a number of other skin problems. One particularly difficult group of disorders is the photosensitive dermatoses, including solar urticaria. Bissonnette et al. describe an innovative approach to the management of refractory solar urticaria with plasma exchange. In the Grand Rounds section, Strauss et al. review the case of an acute SLE and give an insightful discussionrelated to bullous eruptions in acutely ill children. The mechanism of ultraviolet-light-induced carcinogenesis involves UV-induced DNA damage. Over the past decade, it has become clear that tumour suppressor genes can regulate theseprocesses. In the Review section, Tron et al. discuss the role of the suppressorgene p53, which is mutated or lost in nonmelanoma skin cancer. P53 is crucial inprotecting keratinocytes from the harmful effects of ultraviolet radiation, and in their instructive article, these authors use gene-targeted mutant mice lacking p53 to further evaluate the role in UV-induced DNA damage. With the warm weatherupon us, we are spending more time in the outdoors and, as a result, are exposedto a vast number of environmental onslaughts. These include such things as Rickettsial disease, summarized in our CME section Summary Notes. Furthermore, in a comprehensive review, Dr. Sasseville examines another outdoor threat as he delineates the wide spectrum of plant contact dermatitis. This represents an important and in-depth reference on phytodermatitis. Our specialty, and indeed ALL of medicine, is being dramatically altered by recent advances in our understanding of disease at a molecular level. This new understanding of diseasehas led to the potential of modifying gene expression through the use of gene therapy. This is particularly attractive in skin disease, where gene therapy canbe delivered quite readily through the skin. This advancement is insightfully discussed in the article by Somani et al., "Gene Therapy and Dermatology," whichis both valuable for the cognoscenti and noncognoscenti alike, and serves as an important reference work in this area.

As dermatologists, we have ALL been active in educating patients about sun awareness and sun protection. This is even more important for children, as childhood exposure to ultraviolet light is a significant risk for both melanoma and nonmelanoma skin cancers. The importance of an educational approach in appropriate sun awareness in childhood is further underscored by the recent findings by Rivers et al., in the Vancouver Moles Cohort study, presented at the1999 American Academy of Dermatology meeting. In a placebo-controlled trial, thefindings of Rivers et al. clearly demonstrated that the use of sunscreens can significantly decrease the formation of nevae in children, providing further evidence to support sun awareness education initiatives. The lead article by Gooderham and Guenther in the Basic and Clinical Sciences section evaluates the effectiveness of a particular sun awareness program, and gives valuable insightsinto how more effective approaches may be used in the future. In addition to ultraviolet light playing a causal role in cutaneous malignancies, it is known to induce a number of other skin problems. One particularly difficult group of disorders is the photosensitive dermatoses, including solar urticaria. Bissonnette et al. describe an innovative approach to the management of refractory solar urticaria with plasma exchange. In the Grand Rounds section, Strauss et al. review the case of an acute SLE and give an insightful discussionrelated to bullous eruptions in acutely ill children. The mechanism of ultraviolet-light-induced carcinogenesis involves UV-induced DNA damage. Over the past decade, it has become clear that tumour suppressor genes can regulate theseprocesses. In the Review section, Tron et al. discuss the role of the suppressorgene p53, which is mutated or lost in nonmelanoma skin cancer. P53 is crucial inprotecting keratinocytes from the harmful effects of ultraviolet radiation, and in their instructive article, these authors use gene-targeted mutant mice lacking p53 to further evaluate the role in UV-induced DNA damage. With the warm weatherupon us, we are spending more time in the outdoors and, as a result, are exposedto a vast number of environmental onslaughts. These include such things as Rickettsial disease, summarized in our CME section Summary Notes. Furthermore, in a comprehensive review, Dr. Sasseville examines another outdoor threat as he delineates the wide spectrum of plant contact dermatitis. This represents an important and in-depth reference on phytodermatitis. Our specialty, and indeed ALL of medicine, is being dramatically altered by recent advances in our understanding of disease at a molecular level. This new understanding of diseasehas led to the potential of modifying gene expression through the use of gene therapy. This is particularly attractive in skin disease, where gene therapy canbe delivered quite readily through the skin. This advancement is insightfully discussed in the article by Somani et al., "Gene Therapy and Dermatology," whichis both valuable for the cognoscenti and noncognoscenti alike, and serves as an important reference work in this area.

As dermatologists, we have ALL been active in educating patients about sun awareness and sun protection. This is even more important for children, as childhood exposure to ultraviolet light is a significant risk for both melanoma and nonmelanoma skin cancers. The importance of an educational approach in appropriate sun awareness in childhood is further underscored by the recent findings by Rivers et al., in the Vancouver Moles Cohort study, presented at the1999 American Academy of Dermatology meeting. In a placebo-controlled trial, thefindings of Rivers et al. clearly demonstrated that the use of sunscreens can significantly decrease the formation of nevae in children, providing further evidence to support sun awareness education initiatives. The lead article by Gooderham and Guenther in the Basic and Clinical Sciences section evaluates the effectiveness of a particular sun awareness program, and gives valuable insightsinto how more effective approaches may be used in the future. In addition to ultraviolet light playing a causal role in cutaneous malignancies, it is known to induce a number of other skin problems. One particularly difficult group of disorders is the photosensitive dermatoses, including solar urticaria. Bissonnette et al. describe an innovative approach to the management of refractory solar urticaria with plasma exchange. In the Grand Rounds section, Strauss et al. review the case of an acute SLE and give an insightful discussionrelated to bullous eruptions in acutely ill children. The mechanism of ultraviolet-light-induced carcinogenesis involves UV-induced DNA damage. Over the past decade, it has become clear that tumour suppressor genes can regulate theseprocesses. In the Review section, Tron et al. discuss the role of the suppressorgene p53, which is mutated or lost in nonmelanoma skin cancer. P53 is crucial inprotecting keratinocytes from the harmful effects of ultraviolet radiation, and in their instructive article, these authors use gene-targeted mutant mice lacking p53 to further evaluate the role in UV-induced DNA damage. With the warm weatherupon us, we are spending more time in the outdoors and, as a result, are exposedto a vast number of environmental onslaughts. These include such things as Rickettsial disease, summarized in our CME section Summary Notes. Furthermore, in a comprehensive review, Dr. Sasseville examines another outdoor threat as he delineates the wide spectrum of plant contact dermatitis. This represents an important and in-depth reference on phytodermatitis. Our specialty, and indeed ALL of medicine, is being dramatically altered by recent advances in our understanding of disease at a molecular level. This new understanding of diseasehas led to the potential of modifying gene expression through the use of gene therapy. This is particularly attractive in skin disease, where gene therapy canbe delivered quite readily through the skin. This advancement is insightfully discussed in the article by Somani et al., "Gene Therapy and Dermatology," whichis both valuable for the cognoscenti and noncognoscenti alike, and serves as an important reference work in this area.

In adults, the TP53 tumor suppressor gene is frequently mutated in astrocytic brain tumors which is supposed to represent an early event in their development.In juvenile pilocytic and low-grade astrocytomas, however, TP53 mutations have until now been reported as rare, which has led to the suggestion that these tumors may follow a different molecular pathogenesis with an involvement of genes other than TP53. Our analysis of 20 pilocytic and two low-grade astrocytomas of childhood, based on a comprehensive denaturing gradient gel electrophoresis (DGGE) mutation detection assay of the entire coding region, including ALL splice site junctions of TP53, showed mutations considered as causative in 7 of the 20 (35%) pilocytic astrocytomas and in one of the two low-grade astrocytomas. Our finding is significantly different from the mutation frequency of 1.3% (2/155) previously reported for these tumor types. This may be attributed to the mutation detection system used, which also detects mutations occurring outside the evolutionary conserved region of TP53. Our results suggest that, contrary to thepresent notion, TP53 mutations may well play a role in the development of juvenile astrocytomas. Furthermore, no mutations were found in tumors of patients with progression of residual tumor after postoperative follow-up. This suggests that TP53 mutations may be associated with less aggressive forms of juvenile astrocytomas, analogous to the situation in adult astrocytomas.

The Li-Fraumeni Syndrome (LFS) is a rare, dominantly inherited syndrome that features high risk of cancers in childhood and early adulthood. Affected families tend to develop bone and soft tissue sarcomas, breast cancers, brain tumors, leukemias, and adrenocortical carcinomas. In some kindreds, the genetic abnormality associated with this cancer phenotype is a heterozygous germline mutation in the p53 tumor suppressor gene. Recently, we identified one patient who presented in early childhood with multiple primary cancers and who harbored three germline p53 alterations (R156H and R267Q on the maternal allele and R290Hon the paternal allele). To classify the biologic effects of these alterations, functional properties of each of the p53 mutants were examined using in vitro assays of cellular growth suppression and transcriptional activation. Each aminoacid substitution conferred partial or complete loss of wild-type p53 function, but the child completed normal embryonic development. This observation has not been previously reported in a human, but is consistent with observations of normal embryogenesis in p53-deficient mice.

The Li-Fraumeni Syndrome (LFS) is a rare, dominantly inherited syndrome that features high risk of cancers in childhood and early adulthood. Affected families tend to develop bone and soft tissue sarcomas, breast cancers, brain tumors, leukemias, and adrenocortical carcinomas. In some kindreds, the genetic abnormality associated with this cancer phenotype is a heterozygous germline mutation in the p53 tumor suppressor gene. Recently, we identified one patient who presented in early childhood with multiple primary cancers and who harbored three germline p53 alterations (R156H and R267Q on the maternal allele and R290Hon the paternal allele). To classify the biologic effects of these alterations, functional properties of each of the p53 mutants were examined using in vitro assays of cellular growth suppression and transcriptional activation. Each aminoacid substitution conferred partial or complete loss of wild-type p53 function, but the child completed normal embryonic development. This observation has not been previously reported in a human, but is consistent with observations of normal embryogenesis in p53-deficient mice.

The Li-Fraumeni Syndrome (LFS) is a rare, dominantly inherited syndrome that features high risk of cancers in childhood and early adulthood. Affected families tend to develop bone and soft tissue sarcomas, breast cancers, brain tumors, leukemias, and adrenocortical carcinomas. In some kindreds, the genetic abnormality associated with this cancer phenotype is a heterozygous germline mutation in the p53 tumor suppressor gene. Recently, we identified one patient who presented in early childhood with multiple primary cancers and who harbored three germline p53 alterations (R156H and R267Q on the maternal allele and R290Hon the paternal allele). To classify the biologic effects of these alterations, functional properties of each of the p53 mutants were examined using in vitro assays of cellular growth suppression and transcriptional activation. Each aminoacid substitution conferred partial or complete loss of wild-type p53 function, but the child completed normal embryonic development. This observation has not been previously reported in a human, but is consistent with observations of normal embryogenesis in p53-deficient mice.

The Li-Fraumeni Syndrome (LFS) is a rare, dominantly inherited syndrome that features high risk of cancers in childhood and early adulthood. Affected families tend to develop bone and soft tissue sarcomas, breast cancers, brain tumors, leukemias, and adrenocortical carcinomas. In some kindreds, the genetic abnormality associated with this cancer phenotype is a heterozygous germline mutation in the p53 tumor suppressor gene. Recently, we identified one patient who presented in early childhood with multiple primary cancers and who harbored three germline p53 alterations (R156H and R267Q on the maternal allele and R290Hon the paternal allele). To classify the biologic effects of these alterations, functional properties of each of the p53 mutants were examined using in vitro assays of cellular growth suppression and transcriptional activation. Each aminoacid substitution conferred partial or complete loss of wild-type p53 function, but the child completed normal embryonic development. This observation has not been previously reported in a human, but is consistent with observations of normal embryogenesis in p53-deficient mice.

The Li-Fraumeni Syndrome (LFS) is a rare, dominantly inherited syndrome that features high risk of cancers in childhood and early adulthood. Affected families tend to develop bone and soft tissue sarcomas, breast cancers, brain tumors, leukemias, and adrenocortical carcinomas. In some kindreds, the genetic abnormality associated with this cancer phenotype is a heterozygous germline mutation in the p53 tumor suppressor gene. Recently, we identified one patient who presented in early childhood with multiple primary cancers and who harbored three germline p53 alterations (R156H and R267Q on the maternal allele and R290Hon the paternal allele). To classify the biologic effects of these alterations, functional properties of each of the p53 mutants were examined using in vitro assays of cellular growth suppression and transcriptional activation. Each aminoacid substitution conferred partial or complete loss of wild-type p53 function, but the child completed normal embryonic development. This observation has not been previously reported in a human, but is consistent with observations of normal embryogenesis in p53-deficient mice.

Primary malignant epithelial tumors of the liver (PMETL) are rare in the pediatric age group, and very little is known about their biology as compared with adult tumors. The prognostic value of the DNA contents measured by image analysis and expression of oncogene c-erb2 and tumor suppressor gene p53 were studied in 30 cases of PMETL in children, including 24 with hepatoblastomas (HB)and 6 with hepatocellular carcinomas (HCC). p53 overexpression was detected in 12 out of 26 cases (46.0%), or in 3 of 5 HCC and 9 of 21 HB cases. A relatively high concordance of staining was observed with the two antibodies used (clone DO7, Dako and clone DO1, Santa Cruz Biotechnology). c-erb-B2 did not yield the characteristic membrane staining in any of the 27 cases in which reliable staining was obtained. However, 1 out of 4 patients with HCC and 1 of 23 with HBrevealed strong granular cytoplasmic staining in several neoplastic cells. Interestingly, these were two of the three aneuploid multiploid cases. DNA histograms of 13 out of 29 cases (54.8%) were classified as DNA aneuploid (5/6 HCC and 8/23 HB): nine were hyperdiploid, one was hypodiploid (1HB), and three were multiploid (2HB and 1HCC). In the HB group, DNA aneuploidy was strongly associated with embryonal histological areas, suggesting that a disturbance in the process of cell differentiation is associated with marked genetic aberrations. Only the group of HB was submitted to univariate analysis of survival by the Kaplan-Meier method for age (< 24 months vs. > or = 24 months), sex, preoperative chemotherapy (yes vs. no), residual disease (metastasis, and/or unresectable tumor), p53 expression by immunohistochemistry (positive vs. negative), and DNA ploidy (diploid vs. aneuploid). Only residual disease at the time of diagnosis (P < 0.017) and preoperative chemotherapy (0.030) were found to be negatively correlated with biological behavior, estimated as overall survival. DNA aneuploidy tumors (P < 0.125) and male patients (P = 0.123) showed a trend toward a more aggressive clinical behavior, although the difference was not statistically significant. Combining DNA ploidy and residual disease, patients were categorized into three groups: group I, patients with no adverse prognosticfactors, i.e., diploid tumors without residual disease; group II, patients with only one adverse prognostic factor, i.e., aneuploid tumor or residual disease; and group III, patients with both adverse factors, aneuploid tumors and residualdisease at time of diagnosis. A log-rank test comparing the three survival curves showed a statistically significant difference between them (P < 0.003). Althoughthe series of cases is small, the results of this study highlight the importanceof including DNA ploidy in the protocols designed for HB in children by international cooperative groups.

Li-Fraumeni syndrome is an autosomal dominant disorder that is characterized by various types of cancer in childhood and adult cases. Although hereditary TP53 mutation is very rare in different human cancers, it has been frequently reported in Li-Fraumeni syndrome. On the other hand, hereditary mutations of TP57KIP2, P15INK4B, and P16INK4A, which affect the cell cycle similar to TP53, were observed in some types of cancer. In a Turkish family with the diagnosis of Li-Fraumeni syndrome, we analyzed the mutation pattern of TP53, P57KIP2, P15INK4B, and P16INK4A in the peripheral blood, and loss of heterozygosity (homo/hemizygous deletion) pattern of TP53 and P15INK4B/P16INK4A in two tumor tissues. The propositus had a seminoma, his daughter a medulloblastoma, and one of his healthy cousins, a TP53 codon 292 missense point mutation (AAA-->ATA; Lys-->Ile) in the peripheral blood cells. tumor tissue obtained from the propositus with the seminoma revealed loss of heterozygosity in the TP53 gene. In the analyses of tumor tissues from the propositus and his daughter, a P16INK4A codon 94 missense point mutation (GCG-->GAG; Ala-->Glu) was observed with the hereditary TP53 mutation. P16INK4A codon 94 mutation observed in our family is anovel mutation in Li-Fraumeni syndrome. No other gene alteration in TP53, P57KIP2, P15INK4B, and P16INK4A was observed. Existence of the P16INK4A mutationand the hereditary TP53 mutation with or without loss of heterozygosity in the TP53 gene (seminoma/medulloblastoma) may be evidence for a common mechanism involved in tumorogenesis. The gene alterations in TP53 and P16INK4A genes may be used as tumor markers in our family.

We have analyzed a panel of 14 cases of childhood adrenocortical tumors unselected for family history and have identified germline TP53 mutations in >80%, making this the highest known incidence of a germline mutation in a tumor-suppressor gene in any cancer. The spectrum of germline TP53 mutations detected is remarkably limited. Analysis of tumor tissue for loss of constitutional heterozygosity, with respect to the germline mutant allele and the occurrence of other somatic TP53 mutations, indicates complex sequences of genetic events in a number of tumors. None of the families had cancer histories that conformed to the criteria for Li-Fraumeni syndrome, but, in some families, we were able to demonstrate that the mutation had been inherited. In these families there were gene carriers unaffected in their 40s and 50s, and there were others with relatively late-onset cancers. These data provide evidence that certain TP53 alleles confer relatively low penetrance for predisposition to the development of cancer, and they imply that deleterious TP53 mutations may be more frequent in the population than has been estimated previously. Our findings haveconsiderable implications for the clinical management of children with andrenocortical tumors and their parents, in terms of both genetic testing and the early detection and treatment of tumors.

We have analyzed a panel of 14 cases of childhood adrenocortical tumors unselected for family history and have identified germline TP53 mutations in >80%, making this the highest known incidence of a germline mutation in a tumor-suppressor gene in any cancer. The spectrum of germline TP53 mutations detected is remarkably limited. Analysis of tumor tissue for loss of constitutional heterozygosity, with respect to the germline mutant allele and the occurrence of other somatic TP53 mutations, indicates complex sequences of genetic events in a number of tumors. None of the families had cancer histories that conformed to the criteria for Li-Fraumeni syndrome, but, in some families, we were able to demonstrate that the mutation had been inherited. In these families there were gene carriers unaffected in their 40s and 50s, and there were others with relatively late-onset cancers. These data provide evidence that certain TP53 alleles confer relatively low penetrance for predisposition to the development of cancer, and they imply that deleterious TP53 mutations may be more frequent in the population than has been estimated previously. Our findings haveconsiderable implications for the clinical management of children with andrenocortical tumors and their parents, in terms of both genetic testing and the early detection and treatment of tumors.

Rhabdomyosarcomas are a heterogeneous group of malignant tumors and are the mostcommon soft-tissue sarcoma of childhood. Rhabdomyosarcomas resemble developing skeletal muscle, notably in their expression of the MRF family of transcription factors and the PAX3 and PAX7 genes. These PAX genes are also involved through specific translocations, t(2;13)(q35;q14) and variant t(1;13)(p36;q14) in the alveolar subtype, which result in PAX3-FKHR and PAX7-FKHR fusion genes, respectively. The fusion genes are thought critically to affect downstream targets of PAX3 and PAX7 or possibly have novel targets. Similar downstream changes may also be involved in embryonal and fusion gene negative cases. Genomic amplification of such genes as MYCN, MDM2, CDK4, and PAX7-FKHR is a feature mainly of the alveolar subtype, while specific chromosomal gains, including chromosomes 2, 8, 12, and 13, are associated with the embryonal subtype. Loss ofalleles and imprinting at 11p15.5 and disruption of genes such as IGF2, ATR, PTC, P16, and TP53 have also been implicated in rhabdomyosarcoma development. Whereasthere is now a realistic possibility of cure in the majority of cases, there remains a subset that is resistant to multimodality therapy, including high-dosechemotherapy. Characterization of the defining molecular features of tumors thatare likely to behave aggressively represents a particular challenge. Current research is leading toward a better understanding of rhabdomyosarcoma tumorigenesis, which may ultimately result in novel therapeutic strategies that increase the overall cure. Genes Chromosomes cancer 26:275-285, 1999.#CI- Copyright 1999 Wiley-Liss, Inc.

Sun exposure histories were obtained from a series of patients age 35 or youngerfollowing diagnosis and removal of a basal cell carcinoma (BCC). The DNA was extracted from tumor biopsy samples derived from BCC of 10 patients who reportedthat they did not use sunscreens during youth (age 18 or younger) and 10 patients who routinely employed sunscreens during this age period. Exons 5-9 of the p53 gene were then amplified in three fragments from these samples using a nested polymerase chain reaction (PCR) approach and screened for mutations using an RNAheteroduplex assay. ALL PCR products displaying evidence of a mutation were sequenced. It was found that 6 of the 10 patients who were not routine sunscreenusers displayed mutations in these p53 exons. ALL of the mutations were located at dipyrimidine sites, five of the six were C-->T transitions and one mutation was a tandem double mutation, consistent with a role for solar UVB in BCC formation. In contrast, only one p53 mutation was detected in the group of 10 patients who routinely employed sunscreens during childhood and adolescence. Hence, a significantly (P = 0.029) lower level of p53 mutations was detected in the BCC obtained from sunscreen users compared with tumors derived from nonusers. These findings suggest that the mechanisms involved in the etiology of skin carcinogenesis differ in sunscreen users compared with people who did not routinely employ sunscreens. These data are also indicative of a protective effect associated with sunscreen use against the formation of p53 mutations. It is possible that the patients who were diagnosed with BCC despite their use of sunscreens possessed a genetic susceptibility for skin cancer formation and developed BCC through a p53-independent pathway. Alternatively, solar UVA wavelengths, that were generally not blocked by the suncare products employed bythe sunscreen users, may have played a significant role in BCC development through induction of a mutation(s) in an oncogene and/or a tumor suppressor gene, other than p53, for these patients.

Although common among adult intracranial neoplasms, pediatric malignant astrocytomas (PMAs) comprise a relatively small proportion of the brain tumors that occur in children. The scarcity of such cases generally requires that molecular analyses of PMAs are based on the utilization of paraffin-embedded material, and here we have used 39 such specimens to examine the incidence and prognostic significance of oncogene and tumor suppressor gene alterations (including amplifications of EGFR, CDK4, and MDM2 as well as inactivating mutations of CDKN2A, TP53, and PTEN) in these tumors. In general, the frequency of alteration for the genes we have studied fell within ranges that have been reported for adult astrocytomas. However, EGFR amplification, which is usually observed in approximately 40% and 15% of adult grade 4 and grade 3 astrocytomas,respectively, was not detected in any member of this series. With regard to prognosis, PTEN mutations were significantly associated with decreased survival among grade 3 and grade 4 PMA patients, a potentially important observation because neither patient age nor tumor malignancy grade was correlated with outcome for these individuals. In total, our data suggest at least one significant distinction between the genetic etiology of pediatric and adult astrocytomas and additionally reveal that analysis of PTEN mutations in PMA patients may be useful in the differential diagnosis of these tumors.

BACKGROUND: Previous studies have suggested that altered expression or dysfunction of the tumor suppressor gene p53 or the oncogene MDM2 could indicatedisease progression in children with leukemia who would fail to achieve completeremission or who would relapse. While these studies mainly have described aberrations of MDM2 and p53 function at the DNA and mRNA-level, we have examinedp53 and MDM2 expression at the protein level. mutation of the p53 tumor suppressor gene may result in cellular accumulation of the p53 protein, due to prolonged half-life of the abnormal protein. The p53 protein can also be rendered nonfunctional by overexpression of proteins that bind to p53, such as MDM2. Bothpathways have been proposed to disrupt cell cycle regulation in humans. Recent studies have shown that increased expressions of MDM2 as well as of p53 can be detected at the protein level in the absence of gene amplification. PROCEDURE: Forty-three bone marrow samples were analyzed immunohistochemically for p53 and MDM2. Twenty-nine bone marrow samples were obtained in children with active, prognostically unfavorable leukemia and MDS. Fourteen bone marrow samples were from children with non-malignant hematological disorders. RESULTS: p53 protein was expressed in 12 patients and MDM2 in 17 patients with leukemia. In the control group MDM2 expression was detected in one child, while p53 was not foundin any of the samples. CONCLUSIONS: Our findings of p53 or MDM2 positive cells in a majority of children with unfavorable prognostic features suggests that dysfunction of the p53-dependent cell growth control have a role in the development of high risk leukemias.#CI- Copyright 2000 Wiley-Liss, Inc.

We report on two patients in whom osteosarcoma occurred as second malignancy of childhood cancer. One patient had a malignant teratoma and the other adrenocortical carcinoma as the primary cancer. The emergence of cancer in curedcases and long-term survival cases of childhood cancer may result in an increasein the number of osteosarcomas seen in adolescence occurring as second malignancy. Anti-cancer drugs in large does were used for the treatment of a malignant teratoma in the former. These anti-cancer drugs may be involved in theoccurrence of the second malignancy. In the latter, the patient has the germ-line mutation of p53 tumor suppressor gene, so genetic factors are presumably relatedto the occurrence of the second malignancy.

A comparative genomic hybridization (CGH) approach provides identification of genomic gains and losses in a tumor specimen in a single experiment. Only 11 embryonal rhabdomyosarcomas (E-RMS) have previously been subjected to CGH. The underlying genetic events in this histologic subtype are not well defined. In this investigation, 12 E-RMS specimens from 10 patients entered into Intergroup Rhabdomyosarcoma Study (IRS) I-IV and two local patients were analyzed by CGH and fluorescence in situ hybridization (FISH). Gains of chromosomes or chromosomal regions 2 (50%), 7 (42%), 8 (67%), 11 (42%), 12 (58%), 13q21 (33%), and 20 (33%)and losses of 1p35-36.3 (42%), 6 (33%), 9q22 (33%), 14q21-32 (25%), and 17 (25%)were most prominent. Chromosomal regions 1p35-36.3 and 9q22 represent novel regions of loss. Importantly, loss of 9q22 corresponds to the locus of a putative tumor suppressor gene (PTCH), which has been shown to play a role in rhabdomyosarcoma in a mouse model of Gorlin syndrome. Loss of 1p36 corresponds to the locus for PAX7, a paired box containing gene characteristically altered in alveolar rhabdomyosarcoma. Moreover, loss of 1p36 is prominent in another commonpediatric soft tissue tumor, neuroblastoma. Gains of 2, 7, 8, 12, and 13 and loss of 14 were seen in the sole prior E-RMS CGH series; thus, these data provide important confirmatory results. In contrast to this previous study, however loss, not gain, of chromosome 17 was observed in the current study. Chromosome 17 losscorrelates well with previous descriptions of frequent allelic loss of 17p (TP53) in E-RMS. In summary, CGH and FISH analyses of 12 E-RMS specimens revealed novelgenomic imbalances that may be useful in directing further molecular studies forthe determination of E-RMS critically involved genes.#CI- Copyright 2000 Wiley-Liss, Inc.

A specific subset of solid childhood tumors-Wilms' tumor, adrenocortical carcinoma, rhabdomyosarcoma, and hepatoblastoma-is characterized by its association with Beckwith-Wiedemann syndrome. Genetic abnormalities found in these tumors affect the same chromosome region (11p15), which has been implicated in the etiology of Beckwith-Wiedemann syndrome. This suggests that the development of these tumors occurs along a common genetic pathway involving chromosome 11. To search for additional common genetic pathways, this article reviews the genetic data published for these tumors. It was found that, up untilnow, the only genetic abnormalities detected in ALL four tumors affect chromosome band 11p15 and the TP53 gene. In addition, there are several aberrations that occur in two or three of the neoplasms. It is concluded that, of the four tumors, the genetic relationship is most evident between Wilms' tumor and rhabdomyosarcoma.#CI- Copyright 2000 Wiley-Liss, Inc.

Classification of high grade astrocytomas of children into genetic subtypes similar to the adult remains to be defined. Here we report an extensive characterization of 29 high grade pediatric astrocytomas, 7 WHO grade III and 22WHO grade IV, for genetic alterations frequently observed in high grade adult astrocytomas occurring in either the p53/MDM2/p14ARF or Rb/CDK4/p16INK4a tumor suppressor pathways. In addition, we have assessed the contribution of EGFR overexpression and amplification and LOH for chromosome 10, two genetic alterations commonly associated with the development of de novo adult glioblastoma for their roles in the development of de novo astrocytomas of childhood. Our results suggest two major differences in the genetic pathway(s) leading to the formation of de novo high grade astrocytomas in children comparedwith those of the adult. Our findings show preferential inactivation of the p53 tumor suppressor pathway in >95% of pediatric astrocytomas versus inactivation of the Rb tumor suppressor pathway in <25% of the same tumors. In addition, de novohigh grade pediatric astrocytomas lack amplification of the EGFR gene compared with EGFR amplification in one-third of adult glioblastomas. Since drug treatments and gene therapy strategies exploit specific genetic alterations in tumor cells, our findings have important implications for the future developmentof treatments for high grade pediatric astrocytomas.

CONTEXT: mutations of the p53 tumor suppressor gene are the most frequent alterations observed in human neoplasias affecting adults. In pediatric oncology, however, they have seldom been identified. Wilms' tumor is a renal neoplasia commonly occurring in children and is associated with mutations of the WT1 gene.The correlation between Wilms' tumor and alterations of the p53 gene has not been well established, with a low frequency of mutations having been reported in thistype of tumor. mutation may be associated with advanced stage disease and unfavorable histology. OBJECTIVE: To screen for mutations of the p53 gene by thePCR-SSCP method and DNA sequencing in cases of Wilms' tumor sug-gestive of mutation. DESIGN: Case Report. CASE REPORT: Evaluations of exons 5-9 of the p53 gene in DNA samples extracted by PCR-SSCP from 10 Wilms' tumors in children at different stages, and DNA sequencing. Changes in SSCP analy-sis were observed inexon 8 in two samples. The probable muta-tions were not confirmed by DNA sequencing. The absence of point mutations in p53 gene observed in the 10 samples of Wilms' tumor studied agrees with literature data, with DNA sequencing being of fundamental importance for the confirmation of possible mutations.

BACKGROUND: The p53 tumor suppressor gene is the most commonly mutated gene in human cancer, and mutations arise in a wide variety of tumor types. Wild-type p53 functions as a regulator of apoptosis, so mutations in the p53 gene are generally associated with aggressive tumors and a poor prognosis. PROCEDURE: We have investigated the p53 mutation and MDM2 amplification frequencies in biopsies from pediatric rhabdomyosarcoma (RMS) tumors and cell lines by SSCP and Southern analyses. RESULTS: A mutation was detected in only 1 of 20 tumor specimens (5%),whereas the frequency in established RMS cell lines was significantly higher (6/10, 60%). p53 mutations were more common in cell lines derived from tumors previously exposed to chemotherapy compared to those derived from tumors at di-agnosis, and it is likely that these mutations enhanced the probability of successful long-term culture. The frequency of MDM2 gene amplification in patient biopsies was also low (2/20, 10%). Interestingly, complete responses to treatment were obtained in the two patients with tumors that demonstrated amplification ofMDM2. The response to treatment of patients with tumors wild-type for p53 and without MDM2 amplification was quite varied, indicating that expression of a wild-type p53 gene at diagnosis cannot always facilitate a favorable outcome. CONCLUSIONS: p53 mutation and MDM2 gene amplification frequencies are extremely low in RMS tumors, but a wild-type p53 genotype is not always associated with a favorable prognosis.#CI- Copyright 2000 Wiley-Liss, Inc.

The concurrence of acute lymphoblastic leukemia (ALL) and an asymptomatic juvenile pilocytic astrocytoma is described. A 6-year-old boy without clinical evidence of neurofibromatosis had a juvenile pilocytic astrocytoma diagnosed on radiologic examination and before treatment of acute pre-B cell lymphoblastic leukemia. The patient has had a partial resection of the astrocytoma and is 9 months into treatment of his ALL, which is in complete remission. p53 gene mutation was not identified in this patient. The concurrent diagnosis before treatment of ALL and juvenile pilocytic astrocytoma, the latter normally an indolent tumor, suggests that some cases of astrocytoma previously ascribed to radiotherapy or other treatment may in fact be caused by other factors.

OBJECTIVE: We discuss the clinical aspects, pathology, and molecular genetics of7 patients with primitive neuroectodermal tumors (PNETs) arising in the brainstem that were treated at our institution from 1986 through 1995. Most neuro-oncologists avoid performing biopsies in children with pontine tumors. This article raises the question as to whether biopsies should be performed, because treatment recommendations might differ if a PNET was diagnosed rather than a pontine glioma. PATIENTS AND METHODS: We reviewed the clinical neuro-oncology database and the files of the Division of Neuropathology at New York University Medical Center from 1986 through 1995 and identified 7 histologically confirmed PNETs arising in the brainstem among 146 pediatric brainstem tumors. The clinical, neuroradiological, and neuropathological data were reviewed. Postmortem examinations were performed in 2 cases. Formalin-fixed, paraffin-embedded tumor tissues were also available in 6 of 7 patients that were tested for p53 gene mutations using single-strand conformation polymorphism analysis. We also tested9 cerebellar PNETs, 9 brainstem gliomas, and 3 normal brains for p53 gene mutations as controls. RESULTS: ALL 7 patients presented with focal cranial nerve deficits, and 2 were also hemiparetic. The median age at diagnosis was 2.7 (1-8 years). Magnetic resonance imaging (MRI) characteristics included a focal intrinsic exophytic nonenhancing brainstem lesion that had low T1-weighted and high T2-weighted signals. Hydrocephalus was present in 5 patients at diagnosis, 3 of whom had leptomeningeal dissemination. Meningeal dissemination occurred laterin the course of the disease in 3 other patients. Five children required shunts at diagnosis and another 2 at recurrence. Despite therapy, ALL 7 PNET patients died within 17 months of diagnosis with a mean survival of 8 (4-17) months. No mutation in the p53 gene was detected. CONCLUSIONS: Brainstem PNETs tend to arise at a younger age than brainstem gliomas and medulloblastomas. The MRI pattern suggests a localized rather than a diffuse intrinsic nonenhancing brainstem tumor. Like other PNETs, brainstem PNETs have a high predilection to disseminatewithin the central nervous system. The absence of p53 mutations is similar to other PNETs. Despite their origin close to the cerebellum, brainstem PNETs exhibit a more aggressive behavior and result in worse clinical outcomes than docerebellar PNETs.

HYPOTHESIS: Mutant p53 gene has lost its tumor suppression function and is considered to be a very important step in hepatocellular carcinoma development. We propose that the mutant p53 gene plays a role in its invasiveness and prognosis after resection. DESIGN: A case-controlled study. SETTING: A referral center. PATIENTS: Seventy-nine consecutive patients who underwent surgical resection for hepatocellular carcinoma entered this study. INTERVENTION: Tissue sections of resected hepatocellular carcinoma (deparaffinized and rehydrated from formalin-fixed and paraffin-embedded sections) were incubated with antihuman p53monoclonal antibody and immunostained. The p53 result was scored without prior knowledge of the patients' status. A 10% immunopositivity was regarded as the threshold value. MAIN OUTCOME MEASURE: The immunopositive rate of p53 was 69.6% (55 of 79 patients). The clinical variables (age, sex, associated liver cirrhosis, hepatitis B virus infection, hepatitis C virus infection, serum alpha-fetoprotein, and child-Pugh class); the histological variables (size, capsule, vascular permeation; grade of differentiation, and multinodularity); and postoperative course (recurrence, tumor-free interval, death, and survival period) were correlated with p53 immunopositivity. RESULTS: From univariate analysis, more patients with p53 positivity were male (92.7 vs 0%) (P<.001); hadvascular permeation (80% vs 50%) (P =.007) (odds ratio [OR], 4.0); no complete capsule (83.6% vs 62.5%) (P =.04) (OR, 3.1); and daughter nodules (90.9% vs 70.8%) (P =.04) (OR, 4.1) than patients with negative p53 staining. From multivariate analysis, only sex and vascular permeation remained significant (P =.001 and P =.008, respectively). Although more patients with p53 positivity hadtumor recurrence (78% vs 50%) (P =.01) and death (64% vs 33%) (P =. 01), the Coxproportional hazards model showed that p53 overexpression had only weak correlations with tumor-free interval and survival time (P =.09 and P =.08, respectively). CONCLUSIONS: Our results show that the biological behavior of themutant p53 gene is strongly related to the invasiveness of hepatocellular carcinoma and may also influence the postoperative course. We suggest that the immunopositivity of the mutant p53 gene has a predictive role in the prognosis of patients with resected hepatocellular carcinoma.

Brain tumors are among the most common forms of cancer in children and account for most cancer-related deaths in this age group. The incidence of brain tumors appears to be increasing in children, while therapeutic advances have been modest. Few genetic studies exist on pediatric brain tumors, in part because tissue from low-grade and brain stem tumors is not readily available, and also because individual centers have relatively few cases. Genetic changes in infiltrating astrocytomas involve genes in the p53 and RB pathways, and show alterations that are similar to infiltrating astrocytomas in adults. The PTC gene is mutated in a subgroup of medulloblastomas, and may lead to increased proliferation in granule cells that normally express this receptor. Further studies are needed to identify genetic alterations in pilocytic and low-grade astrocytomas, which account for 40% of brain tumors in children.

Brain malignancies represent the most common solid tumors in children, and they are responsible for significant mortality and morbidity. The molecular basis of the most common malignant pediatric brain tumor, medulloblastoma, is poorly understood. mutations in several genes including the human homologue of the Drosophila segment polarity gene, patched (PTCH), the adenomatous polyposis coligene (APC), beta-catenin, and p53 have been reported in subsets of hereditary and sporadic medulloblastoma. Inactivation of one Ptc allele in mice results in a 14% incidence of medulloblastoma. Here, we report a dramatic increase in the incidence (>95%) and accelerated development (prior to 12 weeks of age) of medulloblastoma in mice heterozygous for Ptc that lack p53. The acceleration of tumorigenesis in Ptc+/- mice is specific for loss of p53, because no change in tumor incidence was observed in Ptc+/- mice carrying a mutation in APC (Min+/-) or in Ptc+/- mice deficient in p19ARF. Thus, there is a specific interaction between p53 loss and heterozygosity of Ptc that results in medulloblastoma. Thismay be a consequence of increased genomic instability associated with loss of p53 function that may enhance the rate of acquisition of secondary mutations. Ptc+/-p53-/- mice provide a useful model for investigation of the molecular bases of medulloblastoma and for evaluation of the efficacy of therapeutic intervention strategies in a spontaneously arising endogenous brain tumor.

Colorectal carcinoma rarely affects children and has a dismal prognosis with 5-year survival rates as low as 2.5%-7% despite apparently radical surgery. Herewe report the case of an adenocarcinoma of the sigmoid colon in a 15-year-old girl preceded by uncertain abdominal complaints of 5 years' duration. Pathological work-up revealed a tumour with lymph node metastases (pT3NI). Immunohistochemical evidence of p53 overexpression by the tumour cells raised the suspicion of an underlying Li-Fraumeni syndrome. In addition, there were aphthoid ulceration, fissuration of the non-tumorous mucosa, along with a mixed transmural infiltrate composed of macrophages, eosinophils, and non-typical giant cells, which were compatible with simultaneous Crohn's disease. Anamnestic data concerning the occurrence of idiopathic inflammatory bowel disease or colorectalcarcinoma in the patient's relatives were non-contributory. The present results suggest a possible relationship between Crohn's disease and colon cancer due to the defective p53 gene product.

Length alterations in microsatellite repeats, termed microsatellite instability (MSI), are found in 10-15% of sporadic colon, endometrial, and gastric cancers harboring defects in DNA mismatch repair (MMR) genes We used the microsatellite markers Big Adenine Tract (BAT) 26 and BAT-25 from the reference panel of five markers recommended by the National cancer Institute to evaluate the incidence of MSI in 206 central nervous system tumors. We screened 102 pediatric and 104 adult cases representing 165 astrocytic and 41 nonastrocytic tumors. The overall incidence of MSI was 8% (16 of 206). ALL 16 tumors with MSI were found in pediatric rather than adult patients. MSI was associated with two distinct subtypes of pediatric tumors occurring in 27% (12 of 45) of WHO grade III and grade IV astrocytomas and 24% (4 of 17) of gangliogliomas We evaluated the difference in clinicopathological and genetic features among 45 high-grade pediatric astrocytomas by MSI status. The median survival for pediatric patientswith MSI (n = 12) was 8 months compared with 15 months for those patients without MSI (n = 33; P = 0.18). The frequency of p53 gene mutations was 13% for pediatric patients with MSI (n = 8) compared with 47% for those patients without MSI (n = 19; P = 0.19). These results revealed a trend between MSI status and prog nosis and MSI status and frequency of p53 gene mutations. Our data suggest that pediatric high-grade astrocytomas can be attributed to two different genetic pathways: a MMR-deficient pathway and a MMR proficient pathway.

An 8-year-old girl presented with a cerebral tumor and 3 recurrences within 15 months. The primary tumor was a low-grade astrocytoma, but the recurrences showed progressively malignant phenotypes with increasing mitotic activity and MIB-1 labeling indices. Radiotherapy was given between the first and the second recurrences. Cytogenetic analysis of the first and the second recurrences showedabnormal karyotypes. There seemed to be 2 common breakpoints in these 2 recurrences. TP53 gene mutation screening, using comprehensive denaturing gradient gel electrophoresis, revealed among others a possibly causative mutation of exon 5 in 3 of 4 tumor samples. The meaning of TP53 mutations in low-grade astrocytomas is still unclear, but the highly abnormal karyotypes, which are unusual in these tumors, probably provide genetic evidence for the unexpected aggressive behavior of the tumor in this patient.

pediatric pituitary adenomas are thought to behave more aggressively than their adult counterparts, and the ability to predict the degree of such behavior remains elusive. Proliferation marker Ki-67 and tumor suppressor gene p53 mutations have been used in adults to assist in the evaluation of invasiveness and recurrence; however, their use in childhood and adolescence remains anecdotal. Our study evaluates the proliferative potential in pituitary adenomasof five patients and its relationship with recurrence or persistence of endocrinologic or clinical abnormalities. For such assessment, tissues were stained with monoclonal antibodies BP53-12 forp53 tumor suppressor gene mutationand MIB-1, which binds to cell cycle-specific nuclear antigen Ki-67. In our series, one patient with recurrent adenoma demonstrated the highest (50%) p53 immunoreactivity. Ki-67-stained nuclei ranged from 0 to 2%, failing to identify the recurrent tumor. Therefore, p53 immunoreactivity, rather than Ki-67 nuclear stain, may be useful for identification of recurrent pituitary adenomas in childhood and adolescence.

Retinoblastoma is the most common intraocular tumor of childhood and has served as a model for the understanding or tumorigenesis. This study retrospectively examines the clinicopathologic features of 19 retinoblastomas and defines the MIB-1 (cell proliferation marker), p53 (tumor suppression gene), and CD99 (HBA71or MIC2 antibody) immunoreactivity in 10 selected cases. Nineteen patients (11 boys), ranging in age from 6 to 47 months (mean, 20 months), were included for study. Clinical presentations included: leukocoria (n = 12), strabismus (n = 6),apparent decreased visual acuity (n = 5), and proptosis (n = 1). Five patients had bilateral tumors and one neoplasm arose in a patient with a known family history of retinoblastoma. ALL tumors were histologically characterized by a proliferation of small cells with high nuclear-to-cytoplasmic ratios. Commonly encountered histologic features included necrosis (n = 17, 89%), calcification (n = 16, 84%), fleurettes (n = 14, 74%), and Flexner-Wintersteiner rosettes (n = 11, 58%). Retinal involvement was noted in 18 tumors (95%) and optic nerve invasion in six cases (32%). The surgical optic nerve margin was positive in one case. Mitosis counts were evaluable in 18 cases and ranged from 1 to 42 mitotic figures/10 high power field (mean, 13 mitotic figures/10 high power field). Ten tumors were evaluated with MIB-1, p53, and CD99 antibodies by paraffin immunohistochemistry. MIB-1 labeling indices ranged from 31.4 to 77.1 (mean, 49.4). p53 immunostaining was observed in six tumors; less than 10% of tumor cells were noted to be p53 positive in each case. CD99 positivity was demonstrable focally in three tumors. Adjuvant chemotherapy and/or radiation therapy was administered in six patients. tumor recurrence was not observed in any of the patients with a mean follow-up of 8.9 years. Only one patient died (20 years after enucleation) because of metastatic osteosarcoma. In conclusion: (1) Fleurettes and Flexner-Wintersteiner rosettes are variable findings in retinoblastoma. (2) Retinoblastomas are characterized by marked cell proliferation as evidenced by generally high mitosis counts and extremely high MIB-1 labeling indices, but this does not appear to adversely impact on prognosis. (3) Unlike peripheral primitive neuroectodermal tumors, most retinoblastomas do not stain positively with antibody to CD99. (4) Limited p53 immunostaining was present in 60% of tumors studied. (5) Enucleation with negative optic nerve margin is potentially curative in patients with retinoblastoma.

The Li-Fraumeni syndrome (LFS) is an inherited form of cancer, affecting children and young adults, and characterized by a wide spectrum of tumors, including soft-tissue and bone sarcomas, brain tumours, adenocortical tumours and premenopausal breast cancers. In most of the families, LFS results from germlinemutations of the tumor suppressor TP53 gene encoding a transcriptional factor able to regulate cell cycle and apoptosis when DNA damage occurs. Recently, germline mutations of hCHK2 encoding a kinase, regulating cell cycle via Cdc25C and TP53, were identified in affected families. The LFS working group recommendations are the following: (i) positive testing (screening for a germline TP53 mutation in a patient with a tumor) can be offered both to children and adults in the context of genetic counseling associated to psychological support,to confirm the diagnosis of LFS on a molecular basis. This will allow to offer to the patient a regular clinical review in order to avoid a delay to the diagnosisof another tumor; (ii) the 3 indications for positive testing are: a proband with a tumor belonging to the narrow LFS spectrum and developed before age 36 and, atleast, first- or second-degree relative with a LFS spectrum tumor, before age 46, or a patient with multiple primary tumors, 2 of which belonging to the narrow LFS spectrum, the first being developed before 36 or a child with an adenocortical tumour; (iii) presymptomatic testing must be restricted to adults; (iv) the young age of onset of the LFS tumors the prognosis of some tumors, the impossibility to ensure an efficient early detection and the risk for mutation carriers to develop multiple primary tumors justify that prenatal diagnosis might be considered in affected families.

cancers of the central nervous system are the most common solid tumors of childhood. Although somatic alterations of the p53 tumor suppressor gene have been implicated in brain tumorigenesis, the role of germline p53 mutations in the development of childhood brain tumors has not been well defined. As a component of an ongoing extensive study of the epidemiology of childhood brain tumors, we prospectively examined the germline and tumor p53 gene status in 85 children without a family history of cancer who were diagnosed with a sporadic malignant central nervous system tumor. Using PCR/single-strand conformational polymorphism analysis and direct DNA sequencing, 85 children were screened for the presence of constitutional p53 sequence alterations in exons 2 and 4 through 11. No mutations were identified. Commonly reported sequence polymorphisms were observed at codon72, as well as in 2 other previously described nucleotide residues. Forty-four brain tumor samples were available for analysis and of these 40 were paired withperipheral blood. Once again, no p53 mutations were found. Of the 5 germline samples with the 2 common polymorphisms, only one had a paired tumor sample for comparison and the tumor contained the same alteration as the germline. Of note,one tumor, a PNET of the cerebellum (medulloblastoma), showed loss of heterozygosity at codon 72. We can conclude that the frequency of germline and somatic p53 mutations in sporadic childhood brain tumors is very low, probably less than 1%, and there is no need to screen these patients routinely for their germline p53 status. However, the potential significance of LOH at codon 72 remains to be elucidated.

cancers of the central nervous system are the most common solid tumors of childhood. Although somatic alterations of the p53 tumor suppressor gene have been implicated in brain tumorigenesis, the role of germline p53 mutations in the development of childhood brain tumors has not been well defined. As a component of an ongoing extensive study of the epidemiology of childhood brain tumors, we prospectively examined the germline and tumor p53 gene status in 85 children without a family history of cancer who were diagnosed with a sporadic malignant central nervous system tumor. Using PCR/single-strand conformational polymorphism analysis and direct DNA sequencing, 85 children were screened for the presence of constitutional p53 sequence alterations in exons 2 and 4 through 11. No mutations were identified. Commonly reported sequence polymorphisms were observed at codon72, as well as in 2 other previously described nucleotide residues. Forty-four brain tumor samples were available for analysis and of these 40 were paired withperipheral blood. Once again, no p53 mutations were found. Of the 5 germline samples with the 2 common polymorphisms, only one had a paired tumor sample for comparison and the tumor contained the same alteration as the germline. Of note,one tumor, a PNET of the cerebellum (medulloblastoma), showed loss of heterozygosity at codon 72. We can conclude that the frequency of germline and somatic p53 mutations in sporadic childhood brain tumors is very low, probably less than 1%, and there is no need to screen these patients routinely for their germline p53 status. However, the potential significance of LOH at codon 72 remains to be elucidated.

Medulloblastomas exhibit an array of diverse cytogenetic abnormalities. To evaluate the significance of epigenetic rather than genetic lesions in medulloblastomas and other primitive neuroectodermal tumors (PNETs) of the childhood CNS we performed a systematic analysis of gene specific and global methylation. Methylation-specific PCR detected no methylation for p15(INK4B), von Hippel Lindau and TP53 and only limited methylation for E-Cadherin and p16(INK4A) in tumors. The cell lines Daoy and MHH-PNET-5 in which the p16(INK4A) promoter was methylated did not express the gene, but demonstrated abnormalities by SSCP.Immunohistochemistry for p16 was negative in ALL examined normal cerebella and medulloblastomas. Using the technique of Restriction Landmark Genomic Scanning we detected methylation affecting up to 1% of ALL CpG islands in primary MB/PNETs and 6% in MB cell lines. Methylation patterns differed between medulloblastomas and PNETs. Examination of several methylated sequences revealed homologies to known genes and expressed sequences. Analysis of survival data identified seven of 30 hypermethylated sequences significantly correlating with poor prognosis. We suggest that DNA hypermethylation has an outstanding potential for the identification of novel tumor suppressors as well as diagnostic and therapeutic targets in MBs and other PNETs of the CNS.

mutations of the p53 tumor suppressor gene are the single most common genetic alterations in human cancers. Recently, a distinct nucleotide substitution was identified in exon 10 of the p53 gene, leading to an Arg337His mutation in 97% of children with adrenocortical tumors from Southern Brazil. In the present study, we investigated the presence of this mutation in a larger series of 55 patients (37 adults and 18 children) with benign and malignant sporadic adrenocortical tumors. None of the patients had family cancer histories that conformed to the criteria for Li-Fraumeni syndrome. Twenty-one asymptomatic close relatives of patients with p53 mutations and 60 normal unrelated individuals were also studied. The missense Arg337His mutation was identified in 19 patients (14 children and 5 adults), and 8 of 11 cases studied had LOH. Among the 19 patientswith the Arg337His mutation, only one boy and three adults showed fatal evolution or recurrent metastases. This mutation was also identified in heterozygous statein asymptomatic first-degree relatives of the patients, indicating that Arg337His mutation was inherited in most cases. In contrast, this mutation was not found in 120 alleles of normal unrelated controls. In conclusion, the germ line Arg337Hismutation of p53 protein is present at a high frequency (77.7%) in children with benign or malignant sporadic adrenocortical tumors, but it is not restricted to the pediatric group, since 13.5% of adults with adrenocortical tumors also had this mutation. The presence of this mutation was related to unfavorable prognosis in most of the adults, but not in the children with adrenocortical tumors.

Case vignette: sharing unanticipated genetic information. The Questor family hasexperienced an unusual number of malignancies in the past two generations and has been advised by an oncologist that the p53 oncogene known as Li-Fraumeni Syndrome may be present in the family genome. The option of predictive genetic testing has been raised and several branches of the family have chosen to undergo screening to determine whether they are at risk for cancer because of the gene. Roger and Liz Questor have arranged for screening of themselves and their three children, ages 12, 10, and 7. The couple has, by ALL appearances, been happily married for14 years. None of the family members are found to carry the oncogene; however, the geneticist conducting the analyses has made an interesting incidental discovery. The 10-year-old child is not the biological progeny of Roger Questor.Although the 12-and 7-year-olds are clearly the biological children of the couple, it is evident that the 10-year-old born to Liz Questor was fathered by aperson other than Roger. What are the ethical obligations of the geneticist withrespect to any sharing or disclosure of the information that has been discoveredincidentally? What course of action, if any, do you recommend?#FAU - Leikin, Sanford

Pancreatoblastomas are unusual malignant neoplasms of the pediatric pancreas that may also rarely affect adults. The molecular pathogenesis of pancreatoblastomas is unknown. They are clinicopathologically distinct from adult pancreatic ductaladenocarcinomas, but their occasional occurrence in patients with Beckwith-Wiedemann syndrome and the case presented here of a pancreatoblastoma in an adult patient with familial adenomatous polyposis (FAP) suggests that they might bear a genetic similarity to other infantile embryonal tumors such as hepatoblastomas. We analyzed a series of nine pancreatoblastomas for mutations common to other embryonal malignancies including somatic alterations in the adenomatous polyposis coli (APC)/beta-catenin pathway and chromosome 11p, using immunohistochemistry for beta-catenin, 5q and 11p allelic loss assays, and direct DNA sequencing of exon 3 of the beta-catenin gene and the mutation cluster region of the APC gene. In addition, we analyzed the pancreatoblastomas for alterationsfound in adult-type pancreatic ductal adenocarcinomas including mutations in theK-ras oncogene and the p53 and DPC4 tumor suppressor genes, using direct DNA sequencing of exon 1 of K-ras and immunohistochemistry for p53 and Dpc4. Allelicloss on chromosome 11p was the most common genetic alteration in pancreatoblastomas, present in 86% (six of seven informative cases). Molecular alterations in the APC/beta-catenin pathway were detected in 67% (six of nine), including five neoplasms with activating mutations of the beta-catenin oncogene and the one FAP-associated tumor with biallelic APC inactivation (germline truncating mutation combined with loss of the wild-type allele); seven neoplasmsshowed abnormal nuclear accumulation of beta-catenin protein. In contrast, loss of Dpc4 protein expression was present in only two cases (one diffuse and one focal), and no alterations in the K-ras gene or p53 expression were detected. Our findings indicate that pancreatoblastomas are genetically distinct from the morecommon pancreatic ductal adenocarcinomas, but bear a close molecular pathogenesis to hepatoblastomas. In addition, pancreatoblastoma may represent an extracolonicmanifestation of FAP.

The CHK2 gene encodes a protein kinase that is important for the regulation of cell cycle arrest after DNA damage. CHK2 acts downstream of ataxia teleangiecstasia mutated (ATM), modulates the function of p53 and may help mediate cell cycle arrest at G2/M by phosphorylation of Cdc25C. Recently, the human homolog of the checkpoint kinase Cds1 (CHK2) has been suggested to be a tumor suppressor gene. Heterozygous germline mutations have been reported in Li-Fraumeni syndrome (LFS), a highly penetrant familial cancer phenotype, and insporadic colon cancer. LFS is associated with the development of lymphoid malignancies, especially childhood ALL. Therefore, we analyzed the DNA from 143 lymphoid malignancies to determine whether they had mutations of the CHK2 gene. The 14 exons of CHK2 were studied by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and sequencing of aberrantly migrating bands. One missense mutation changing serine to phenylalanine (codon 428) in an evolutionarily highly conserved domain was found in a non-Hodgkin's aggressive lymphoma. Another point mutation in the non-coding region was identified in one of adult T-cell leukemias (ATL) samples. This result suggests that mutation of the CHK2 gene may rarely be involved in the development of selected lymphomas.

CONTEXT: mutations or deletions in the tumor-suppressor gene p53 are among the commonest genetic changes found in human neoplasms including breast, lung and bowel cancers. In hematological malignancies, p53 is most often mutated in Burkitt's lymphoma, with p53 mutations present in 30 to 40% of tumor samples andin 70% of cell lines. OBJECTIVE: To analyze the p53 gene alterations in child patients with B non-Hodgkin's lymphoma. DESIGN: Descriptive study. SETTING: Tertiary oncology care center. PARTICIPANTS: The study investigated 12 patients with childhood B non-Hodgkin's lymphoma (Burkitt's lymphoma). Screening for p53 mutations was done by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis of exon 5 to 8/9 of the gene. RESULTS: Abnormalpolymerase chain reaction-single strand conformational polymorphism migration pattern was observed in 4 patients (33.3%), one on exon 6 and three on exon 7. Positive cases included 2 patients who died from disease. CONCLUSION: These preliminary results suggest that p53 mutations are quite frequent in children with Burkitt's lymphoma and may play a role in lymphoma genesis or disease progression.

In this report, we present a simple and powerful way to incorporate individual-specific liability classes into linkage analysis. The proposed methodis applicable to both quantitative and qualitative traits. In linkage studies, we may have information about different covariates. Incorporation of these covariates along with the estimates of residual familial effects, age-at-onset effects, and susceptibility in the definition of liability classes can increase the power to detect genetic linkage. In this study, we show how one can form individual-specific liability classes and use these classes in standard linkage-analysis programs, such as the widely used LINKAGE package, to perform more powerful genetic linkage analysis. Our simulation study shows that this approach yields higher LOD scores and more-accurate estimates of the recombination fraction in the families showing linkage. The proposed method is also applied to kindreds collected, at the M. D. Anderson cancer Center, throughprobands with childhood soft-tissue sarcoma. Confirmed germ-line mutations in the p53 tumor-suppressor gene have been identified in these families. Application ofour method to these families yielded significantly higher LOD scores and more-accurate recombination fractions than did analysis that did not account forindividual-specific covariate information.

BACKGROUND: The prognosis of children with high-grade gliomas is uncertain, evenwhen clinical and histologic findings are considered. We investigated whether mutations in the TP53 gene or the degree of expression of p53 protein in high-grade gliomas is associated with progression-free survival in children withthese tumors. METHODS: Paraffin-embedded specimens of malignant gliomas from children treated in the children's cancer Group study CCG-945 were assessed by mutational analysis of TP53 (121 specimens) and immunohistochemical analysis of p53 (115 specimens). For mutational studies, areas of tissue that contained malignant glioma were isolated by microdissection, and the DNA was subjected to polymerase-chain-reaction-based amplification and sequencing of TP53 exons 5, 6,7, and 8. Immunohistochemical analysis was performed with the use of a microwave-enhanced antigen retrieval and an antibody that bound both wild-type and mutant p53. RESULTS: We found a significant association between overexpression of p53 and outcome; this association was independent of histologic features, age, sex, the extent of resection, and tumor location. The rate ( +/- SE) of progression-free survival at five years was 44 +/- 6 percent in the groupof 74 patients whose tumors had low levels of expression of p53 and 17 +/- 6 percent in the group of 41 patients whose tumors had overexpression of p53 (P<0.001). A nonsignificant association was observed between mutations in TP53 and outcome. CONCLUSIONS: Overexpression of p53 in malignant gliomas during childhood is strongly associated with an adverse outcome, independently of clinical prognostic factors and histologic findings.

BACKGROUND: Whereas in sporadic human malignancies mutations of the TP53 tumor-suppressor gene occur in cancers of almost every organ and histologic subtype, patients with an inborn TP53 defect are at high risk to develop, in particular, soft tissue and bone sarcomas, brain tumors, leukaemias, adrenocortical tumors, and breast cancer. To demonstrate the usefulness of microarray technology applied to TP53 sequencing in pediatric tumors, we investigated young patients suffering from tumors typical of the Li-Fraumeni context who were, therefore, candidates for harboring inborn defects in tumor-suppressor genes. PROCEDURE: Six individuals were studied, including typical Li-Fraumeni patients as well as patients without any family history of cancer. DNA samples were independently analyzed for TP53 mutations by GeneChip and standard automated laser fluorescence (ALF) sequencing technology. RESULTS: The tumor and corresponding constitutional DNA samples clearly showed identical mutations which were confirmed by ALF sequencing. ALL coding exons (exons 2-11) of TP53 were analyzed simultaneously. The entire sequencing procedure and data analysis was carried out within 24 hr. CONCLUSIONS: The GeneChip TP53-sequencingassay may be feasible for routine molecular genetic diagnostics in determining the TP53 status of childhood-tumor patients and in enabling a disease managementbased on the genetic background of the individual.#CI- Copyright 2002 Wiley-Liss, Inc.

BACKGROUND: Whereas in sporadic human malignancies mutations of the TP53 tumor-suppressor gene occur in cancers of almost every organ and histologic subtype, patients with an inborn TP53 defect are at high risk to develop, in particular, soft tissue and bone sarcomas, brain tumors, leukaemias, adrenocortical tumors, and breast cancer. To demonstrate the usefulness of microarray technology applied to TP53 sequencing in pediatric tumors, we investigated young patients suffering from tumors typical of the Li-Fraumeni context who were, therefore, candidates for harboring inborn defects in tumor-suppressor genes. PROCEDURE: Six individuals were studied, including typical Li-Fraumeni patients as well as patients without any family history of cancer. DNA samples were independently analyzed for TP53 mutations by GeneChip and standard automated laser fluorescence (ALF) sequencing technology. RESULTS: The tumor and corresponding constitutional DNA samples clearly showed identical mutations which were confirmed by ALF sequencing. ALL coding exons (exons 2-11) of TP53 were analyzed simultaneously. The entire sequencing procedure and data analysis was carried out within 24 hr. CONCLUSIONS: The GeneChip TP53-sequencingassay may be feasible for routine molecular genetic diagnostics in determining the TP53 status of childhood-tumor patients and in enabling a disease managementbased on the genetic background of the individual.#CI- Copyright 2002 Wiley-Liss, Inc.

BACKGROUND: Whereas in sporadic human malignancies mutations of the TP53 tumor-suppressor gene occur in cancers of almost every organ and histologic subtype, patients with an inborn TP53 defect are at high risk to develop, in particular, soft tissue and bone sarcomas, brain tumors, leukaemias, adrenocortical tumors, and breast cancer. To demonstrate the usefulness of microarray technology applied to TP53 sequencing in pediatric tumors, we investigated young patients suffering from tumors typical of the Li-Fraumeni context who were, therefore, candidates for harboring inborn defects in tumor-suppressor genes. PROCEDURE: Six individuals were studied, including typical Li-Fraumeni patients as well as patients without any family history of cancer. DNA samples were independently analyzed for TP53 mutations by GeneChip and standard automated laser fluorescence (ALF) sequencing technology. RESULTS: The tumor and corresponding constitutional DNA samples clearly showed identical mutations which were confirmed by ALF sequencing. ALL coding exons (exons 2-11) of TP53 were analyzed simultaneously. The entire sequencing procedure and data analysis was carried out within 24 hr. CONCLUSIONS: The GeneChip TP53-sequencingassay may be feasible for routine molecular genetic diagnostics in determining the TP53 status of childhood-tumor patients and in enabling a disease managementbased on the genetic background of the individual.#CI- Copyright 2002 Wiley-Liss, Inc.

Mdm2 is an oncogene that binds to and inactivates the tumor suppressor p53. However, the presence of oncogenic splice variants of mdm2 in human tumors that lack the p53 binding site has suggested a p53-independent transforming function for this protein. This report describes expression of 11 different mdm2 splice variants in pediatric rhabdomyosarcoma (RMS) cell lines and tumors at a frequency of 75% and 82%, respectively. Five of these isoforms have previously been described in other tumor histiotypes but six are novel and may be unique to RMS.There was no association between expression of splice variants and mdm2 gene amplification or p53 status. In addition, the frequency of splice variants was much higher than the incidence of mdm2 amplification or p53 mutations. These variants may be important to consider with respect to RMS tumor progression and therapeutic response.

BACKGROUND: Cytokine genetic polymorphisms have been associated with transplant outcome in some experimental and clinical studies, but the cytokine profile of patients who are clinically tolerant has not been investigated. AIM: Allelic variations in tumor necrosis factor (TNF)-alpha, interferon (INF)-gamma, transforming growth factor (TGF)-beta1, interleukin (IL)-6, and IL-10 were evaluated in patients successfully withdrawn from immunosuppression. METHODS: pediatric liver transplant recipients who were successfully withdrawn from immunosuppression (n=12) or who are on minimal immunosuppression (n=7) were genotyped. A control group of liver recipients who required maintenance immunosuppression served as a control group (n=37). RESULTS: Compared to the control group, low TNF- alpha and high/intermediate IL-10 profiles were seen in ALL 12 children maintained off immunosuppression and in 6 of 7 children requiring minimal immunosuppression. CONCLUSION: children successfully maintained off immunosuppression are more likely to have a genetic predisposition toward low TNF-alpha and high/intermediate IL-10 production. children maintained on minimalimmunosuppression exhibit a similar cytokine profile to those successfully weaned.

mutation of p53 has been implicated in progression of classical Wilms tumor (WT)into the anaplastic variant (AWT), drug resistance, and poor prognosis. Because of prognostic similarities, clear cell sarcoma of the kidney (CCSK) has been classified with AWT and other aggressive pediatric renal tumors, apart from congenital mesoblastic nephroma (CMN), which is instead a relatively benign tumor of neonates. Initially, CCSK and CMN were assumed to be ontologically related, but the role of p53 in the pathogenesis of either disease has not been sufficiently evaluated as in AWT. We examined the status of p53 in CMN and CCSK in comparison to AWT by immunohistochemistry and mRNA analysis of p53, the downstream effector p21(WAF-1/CIP-1) ( p21), the multidrug resistance gene MDR-1, a putative target of p53, and the p53-antagonist Mdm-2. Surprisingly, strong p53nuclear immunoreactivity was found in cultures from two CMN specimens, but not in frozen or fixed tumor tissue from five other CMN specimens, nor in cell lines ortumor tissue from CCSK. Sequence analysis excluded p53 mutations. The size of the p53 mRNA in CMN and CCSK primary tumors excluded gross deletions or rearrangements. Low levels of Mdm-2 mRNA in CCSK and CMN primary tumors and cultures did not support a role for Mdm-2. Absence of MDR-1 mRNA excluded MDR-1 in the drug-resistant phenotype of CCSK. Cisplatin-induced p21 transactivation assays and G(1) cell cycle arrest analyses showed that p21 transactivation and G(1) arrest occurred in both CCSK and CMN cultures, demonstrating integrity of the p53 signal transduction pathway. Absence of p53 functional abnormalities excluded relationships between CCSK and CMN as in AWT, supporting the association of cellular CMN with congenital fibrosarcomas as more recently proposed.

A high prevalence of p53 gene mutation and protein expression has been found in the anaplastic variant of Wilms' tumor (WT), known to be associated with poor outcome. However, there are very few studies of p53 alterations in the other tworare and highly malignant renal tumors in childhood, in other words, clear cell sarcoma of the kidney (CCSK) and malignant rhabdoid tumor of the kidney (MRTK). Overexpression of p53 protein has been detected in eight CCSKs in one study, andin two in another, yet no molecular correlation with p53 gene mutations has beencarried out. Our study is the first molecular analysis concerning p53 in CCSK. We investigated eight cases of CCSK and one case of MRTK for p53 protein expressionby immunohistochemical staining. ALL were analyzed for p53 mutations in the region of exons 4 to 8 by polymerase chain reaction-single-strand conformationalpolymorphism (PCR-SSCP) method and DNA sequencing analysis. By histological study, no CCSK showed anaplastic features. None expressed p53 protein, but two harbored p53 mutations. One was in exon 5, with a base pair insertion between codons 162 to 163 causing frameshift alteration in amino acid. Another was a silent CTC-->CTT transversion in codon 289 of exon 8. The case of MRTK did not show any alterations of p53 protein or gene. Our result indicates that p53 alterations are infrequent in CCSK and do not seem to be primary genetic events in the pathogenesis of CCSK.

A high prevalence of p53 gene mutation and protein expression has been found in the anaplastic variant of Wilms' tumor (WT), known to be associated with poor outcome. However, there are very few studies of p53 alterations in the other tworare and highly malignant renal tumors in childhood, in other words, clear cell sarcoma of the kidney (CCSK) and malignant rhabdoid tumor of the kidney (MRTK). Overexpression of p53 protein has been detected in eight CCSKs in one study, andin two in another, yet no molecular correlation with p53 gene mutations has beencarried out. Our study is the first molecular analysis concerning p53 in CCSK. We investigated eight cases of CCSK and one case of MRTK for p53 protein expressionby immunohistochemical staining. ALL were analyzed for p53 mutations in the region of exons 4 to 8 by polymerase chain reaction-single-strand conformationalpolymorphism (PCR-SSCP) method and DNA sequencing analysis. By histological study, no CCSK showed anaplastic features. None expressed p53 protein, but two harbored p53 mutations. One was in exon 5, with a base pair insertion between codons 162 to 163 causing frameshift alteration in amino acid. Another was a silent CTC-->CTT transversion in codon 289 of exon 8. The case of MRTK did not show any alterations of p53 protein or gene. Our result indicates that p53 alterations are infrequent in CCSK and do not seem to be primary genetic events in the pathogenesis of CCSK.

A high prevalence of p53 gene mutation and protein expression has been found in the anaplastic variant of Wilms' tumor (WT), known to be associated with poor outcome. However, there are very few studies of p53 alterations in the other tworare and highly malignant renal tumors in childhood, in other words, clear cell sarcoma of the kidney (CCSK) and malignant rhabdoid tumor of the kidney (MRTK). Overexpression of p53 protein has been detected in eight CCSKs in one study, andin two in another, yet no molecular correlation with p53 gene mutations has beencarried out. Our study is the first molecular analysis concerning p53 in CCSK. We investigated eight cases of CCSK and one case of MRTK for p53 protein expressionby immunohistochemical staining. ALL were analyzed for p53 mutations in the region of exons 4 to 8 by polymerase chain reaction-single-strand conformationalpolymorphism (PCR-SSCP) method and DNA sequencing analysis. By histological study, no CCSK showed anaplastic features. None expressed p53 protein, but two harbored p53 mutations. One was in exon 5, with a base pair insertion between codons 162 to 163 causing frameshift alteration in amino acid. Another was a silent CTC-->CTT transversion in codon 289 of exon 8. The case of MRTK did not show any alterations of p53 protein or gene. Our result indicates that p53 alterations are infrequent in CCSK and do not seem to be primary genetic events in the pathogenesis of CCSK.

Rhabdomyosarcoma (RMS) is a family of soft tissue tumors that are associated with the skeletal muscle lineage and generally occur in the pediatric population. Based on histopathologic features, two subtypes, embryonal (ERMS) and alveolar (ARMS), were identified and associated with distinct clinical characteristics and genetic alterations. ARMS is associated with 2;13 or 1;13 chromosomal translocations, which generate PAX3-FKHR and PAX7-FKHR fusion products, respectively. These translocations result in altered expression, function, and subcellular localization of the fusion products relative to the wild-type proteins, and ultimately contribute to oncogenic behavior by modifying growth, differentiation, and apoptosis pathways. In contrast to the specific translocations found in ARMS, most ERMS cases have allelic loss at chromosome 11p15.5. Chromosome fragment transfer studies demonstrated that this region represses tumor cell growth, suggesting the presence of tumor suppressor gene(s)in this region. In both ERMS and ARMS, there is evidence of collaborating alterations that affect common targets, such as the p53 and RB pathways. One mechanism for perturbing these pathways involves amplification of genes such as MDM2 and CDK4; these amplification events occur frequently in ARMS but only rarely in ERMS. Therefore, despite similarities in the downstream targets of these genetic alterations, the striking cytogenetic and molecular differences between ARMS and ERMS indicate distinct molecular etiologies in these two subtypes.

Twenty-nine pediatric immature teratomas were reviewed to determine the frequency and clinical significance of p53 expression. tumors were stained for p53 expression by immunohistochemistry and results were correlated with the presenceof other germ cell tumor elements and with outcome. Sequencing of p53 for mutations was performed on positive cases. Eighteen cases showed widespread positive p53 staining of the immature teratoma elements, 9 showed staining only in very occasional cells, and 2 cases showed no staining. Of the 18 positive cases, 5 recurred. ALL five were pure immature teratomas at diagnosis. Four recurred as immature or mature teratoma and one as a sarcoma; ALL except one showed frequent cells positive for p53 in the recurrent tumor. Another 5 of the 18 diffusely positive cases contained immature teratoma as well as other malignant germ cell elements at diagnosis; none of these recurred. None of the remaining eight cases with frequent positive cells, the nine cases with occasionally positive p53 staining, or the two cases with no staining recurred or demonstrated other germ cell tumor elements. We conclude that p53 expression is not unusual in immature teratoma and diffuse p53 immunopositivity is associated with recurrence or the presence of malignant elements in approximately 50% of cases. In only 1 of 29 cases tested was p53 immunopositivity associated with mutations in the p53 gene; hence, overexpression in the majority of cases is presumed to reflect increased half-life of the protein from undetermined stabilizing factors. expression of p21, a p53 target gene, was only focal, suggesting impaired transcriptional activation by p53. The finding of frequent p53-positive cells in immature teratoma should prompt a search for malignant elements within the tumor and affected patients should be followed closely for evidence of recurrence.

Amplification of the EGFR, mdm2, CDK4 and PDGFR A genes has been widely demonstrated in adult malignant gliomas, almost exclusively glioblastomas. To determine the role of these mutational events in pediatric astrocytic gliomas weinvestigated the presence of EGFR, mdm2, CDK4 and PDGFR A gene amplification in 38 childhood brain tumor biopsies, including 24 low-grade astrocytomas and 14 malignant tumors. We used differential PCR assay on DNA extracted either from paraffin embedded or frozen tissues. EGFR gene amplification was detected in 4 out of 14 malignant tumors; no low-grade astrocytoma showed amplification. tumors with EGFR gene amplification were negative for the presence of p53 mutations, asobserved in a previous study. One glioblastoma showed PDGFR A amplification, while no amplifications were observed for mdm2 and CDK4 genes. These data are inline with those obtained from studies on gliomas of adults and suggest the existence of two different subsets of malignant gliomas also in pediatric brain tumors: one carrying EGFR gene amplification, the other showing p53 mutations.

The 3p21.3 tumour suppressor gene (TSG) RASSF1A is inactivated predominantly by promoter methylation and rarely by somatic mutations. Recently we demonstrated that epigenetic inactivation of RASSF1A is frequent in both clear cell and papillary adult renal cell carcinomas (even though 3p21.3 allele loss is rare inpapillary tumours). Wilms' tumour is the most common childhood kidney tumour, but relatively little is known about its molecular pathogenesis. Thus TSGs such as WT1, p16(CDKN2a) and p53 are inactivated in only a minority of cases. In view ofthe involvement of RASSF1A in adult renal cancers we investigated RASSF1A as a candidate Wilms' TSG. We detected RASSF1A hypermethylation in 21 of 39 (54%) primary Wilms' tumours. 3p21.3 allele loss was not detected in nine informative Wilms' tumours (five with RASSF1A methylation). In contrast to RASSF1A, only a minority (10.3%) of Wilms' tumours demonstrated p16 promoter methylation. As chromosome 3p allele loss is frequent in colorectal cancer, we proceeded to investigate RASSF1A promoter methylation in colorectal cancer and detected RASSF1A methylation in 80% (4/5) colorectal cancer cell lines and 45% (13/29) primary colorectal cancers. There was no correlation between RASSF1A and p16 methylation in colorectal cancer. We have demonstrated that RASSF1A inactivationis the most frequent genetic or epigenetic event yet reported in Wilms' tumourigenesis and that allelotyping studies may fail to identify regions containing important TSGs.

OBJECTS: Atypical teratoid/rhabdoid tumors (AT/RT) are aggressive neoplasms thatafflict infants and young children. The objective of this retrospective study was to determine the association between DNA content (DNA ploidy, cell cycle analysis), tumor suppressor gene (p53, pRb, p16, and MMAC/PTEN) expression and the biologic aggressiveness of these tumors. METHODS: Eight tumors from 7 patients (1 girl, 6 boys; median age 4+/-6.7 months) were studied. Two patients had DNA aneuploidy and 5 patients manifested diploid DNA content at diagnosis. The proliferative index of the tumors ranged from 10% to 28% (median, 12+/-6.4%). The single tumor with a low proliferative index (i.e., <10%) was aneuploid. Immunohistochemical evaluation of p53, pRb, p16, and MMAC/PTEN expression patterns showed that most of the tumors contained more cells with abnormal pRb and p16 expression than cells with abnormal p53 and MMAC/PTEN expression. expression of tumor suppressor genes, however, was inhomogeneous. CONCLUSION: Our findings led us to conclude that AT/RT of childhood is characterized by a high proliferative index and DNA aneuploidy. The high expression of abnormal pRb and p16 and the low expression of abnormal p53 and MMAC/PTEN indicate alteration of the G1-to-S phase step in the cell cycle, which could be an explanation for the aggressive nature of these tumors.

BACKGROUND: Li-Fraumeni syndrome is a dominantly inherited disorder characterized by early-onset breast cancer, soft-tissue sarcomas and osteosarcomas, acute leukemia, adrenocortical neoplasms and central nervous system tumors. Germline mutations in gene TP53 are identified in a percentage of affected families. PATIENTS AND METHOD: Eight families with aggregation of childhood sarcomas, brain tumors, breast cancers in pre-menopausal women, and renal tumors were screened for TP53 germ-line mutations. SSCP and posterior direct sequencing were performed for genetic analysis. We also report a previously undescribed family with the Li-Fraumeni syndrome carrying a germline mutation. RESULTS: Seven families fulfilled so-called Li-Fraumeni like criteria and one fulfilled classical criteria. A new germ-line mutation in codon 238 at exon 7 of the gene TP53 was identified in the family fulfilling classical criteria. This mutation has not been previously reported. CONCLUSIONS: The clinical heterogeneity as well as themolecular complexity and consequences of mutation analysis and genetic counseling make it necessary to develop protocols in this area. A multidisciplinary approach is needed; this approach should be coordinated by a Familial cancer Genetic Counseling Unit.

BACKGROUND: Li-Fraumeni syndrome is a dominantly inherited disorder characterized by early-onset breast cancer, soft-tissue sarcomas and osteosarcomas, acute leukemia, adrenocortical neoplasms and central nervous system tumors. Germline mutations in gene TP53 are identified in a percentage of affected families. PATIENTS AND METHOD: Eight families with aggregation of childhood sarcomas, brain tumors, breast cancers in pre-menopausal women, and renal tumors were screened for TP53 germ-line mutations. SSCP and posterior direct sequencing were performed for genetic analysis. We also report a previously undescribed family with the Li-Fraumeni syndrome carrying a germline mutation. RESULTS: Seven families fulfilled so-called Li-Fraumeni like criteria and one fulfilled classical criteria. A new germ-line mutation in codon 238 at exon 7 of the gene TP53 was identified in the family fulfilling classical criteria. This mutation has not been previously reported. CONCLUSIONS: The clinical heterogeneity as well as themolecular complexity and consequences of mutation analysis and genetic counseling make it necessary to develop protocols in this area. A multidisciplinary approach is needed; this approach should be coordinated by a Familial cancer Genetic Counseling Unit.

PURPOSE: Langerhans cell histiocytosis (LCH) is a rare pediatric and adult disease causing skin rashes, osteolytic bone lesions, tumorous growth in variousorgans, and in some patients, organ dysfunction. The cause of the disease is obscure, and it is not yet understood why some patients develop single-system lesions only without relapse, whereas others develop fatal multiorgan disease. The expression of p53 tumor suppressor gene product detected immunohistochemically can be used as a guideline to alterations in DNA repair control and apoptosis. The authors have chosen to analyze p53 expression in biopsies from children with LCH and correlate it with clinical manifestation andoutcome in a broad range of organs. PATIENTS AND METHODS: The study was performed on 50 specimens from 32 children (19 boys and 13 girls), median age 3 1/4 years,range 5 months to 12 1/3 years with a definite diagnosis of LCH based on CD1a positivity. The slides were stained with p53 antibody and semiquantitatively evaluated using a grading system from 1 to 5 as an estimate for 0% to 20%, 20% to 40%, 40% to 60%, 60% to 80%, and 80% to 100% p53-positive for pathologic Langerhans cells (pLC), respectively. RESULTS: The p53 protein was expressed in various degrees in pLC in ALL lesions. The degree of p53 expression could not becorrelated to either clinical manifestation or outcome. CONCLUSIONS: An increased expression of p53 in pLC indicates an altered DNA repair control with or withoutabnormal control of apoptosis.

Cutaneous malignant melanoma, the most lethal of the skin cancers, known for itsintractability to current therapies, continues to increase in incidence, providing a significant public health challenge. There is a consensus that skin cancer is initiated by sunlight exposure. For non-melanoma skin cancer there is substantial evidence that chronic exposure to the ultraviolet B radiation (UVB) (280-320 nm) portion of the sunlight spectrum is responsible. Experimentally, UVB is mutagenic and chronic UVB exposure can cause non-melanoma skin cancer in laboratory animals. Non-melanoma tumors in animals and in humans show characteristic UVB signature lesions in the tumor suppressor p53 and/or in the patched (PTCH) gene. An action spectrum or wavelength dependence for squamous cell carcinoma in the mouse shows a major peak of efficacy in the UVB. For malignant melanoma, however, the situation is unclear and the critical direct target(s) of sunlight in initiating melanoma and even the wavelengths responsible are as yet unidentified. This lack of information is in major part a result of apaucity of animal models for melanoma which recapitulate the role of sunlight ininitiating this disease. The epidemiology of melanoma differs significantly fromnon-melanoma skin cancer. Intense sporadic sunlight exposure in childhood, probably exacerbated by additional adult exposure, is associated with elevated melanoma risk. Melanoma is also a disease of gene-environment interactions with underlying genetic factors playing a significant role. These major differences indicate that extrapolation from information for non-melanoma skin cancer to melanoma is unlikely to be useful. We summarize in this review the experimental information available on the role of UV radiation in melanoma and give an overview of animal melanoma models. A new model derived by neonatal UV irradiation of hepatocyte growth factor/scatter factor (HGF/SF) transgenic mice is described which recapitulates the etiology, the histopathology and molecular pathogenesis of human disease. It is anticipated that the HGF/SF transgenic model will provide a means to access the mechanism(s) by which sunlight initiates thislethal disease and provide an appropriate vehicle for derivation of appropriate therapeutic and preventive strategies.

To characterize cancer risk in heterozygous p53 mutation carriers, we analyzed cancer incidence in 56 germline p53 mutation carriers and 3,201 noncarriers from107 kindreds ascertained through patients with childhood soft-tissue sarcoma whowere treated at the University of Texas M. D. Anderson cancer Center. We systematically followed members in these kindreds for cancer incidence for >20 years and evaluated their p53 gene status. We found seven kindreds with germlinep53 mutations that include both missense and truncation mutation types. Kaplan-Meier analysis showed similar cancer risks between 21 missense and 35 truncation p53 mutation carriers (log-rank chi(2)=0.04; P=.84). We found a significantly higher cancer risk in female carriers than in male carriers (log-rank chi(2)=12.1; P<.001), a difference not explained by an excess of sex-specific cancer. The calculated standardized incidence ratio (SIR) showed that mutation carriers had a risk for ALL types of cancer that was much higher than that for the general population (SIR = 41.1; 95% confidence interval [CI] 29.9-55.0) whereas noncarriers had a risk for ALL types of cancer that was similar to that in the general population (SIR = 0.9; 95% CI 0.8-1.0). The calculated SIRs showed a >100-fold higher risk of sarcoma, female breast cancer,and hematologic malignancies for the p53 mutation carriers and agreed with the findings of an earlier segregation analysis based on the same cohort. These results quantitatively illustrated the spectrum of cancer risk in germline p53 mutation carriers and will provide valuable reference for the evaluation and treatment of patients with cancer.

In the present study we review ENT tumor pathology in childhood. Only the most salient aspects are emphasized and the variety of entities reviewed was restricted. Molecular biology techniques reveal infection by human papilloma virus (types 6 and 11) in 50 % of papillomas, while immunohistochemical techniques are less effective in papilloma virus detection. The myofibroblastic nature of nasal angiofibroma has been demonstrated and its incidence is 25 timesmore frequent in patients with familial polyposis of the colon. Overexpression of p53 occurs in the initial stages of nasopharyngeal carcinoma, while overexpression of c-myc is correlated with an unfavorable prognosis. Recently, olfactory neuroblastoma has been shown not to express the protein product of theMIC-2 gene (antibody 12E7), thus the hypothesis that it could be a member of theEwing tumor family (neuroectodermal peripheral tumors) has not been confirmed, although it is a primitive neural tumor. The head and neck rhabdomyosarcoma withthe best prognosis is that located in the orbit, and cytogenetic studies have shown chromosomic translocation t(2;13) in 50 % of these childhood tumors when they are of the alveolar-type, while trisomy of chromosome 2 or 20 is more characteristic of the embryonic-type. Currently, any classifying features of ENTlymphomas must be based on the Revised European-American Classification of Lymphoid Neoplasms (REAL). Papillary and medullary carcinomas are the most common histological types of thyroid carcinoma in childhood. Alterations in ret/PTC play a significant role in the pathogenesis of both.

PURPOSE: To analyze the genetic and epigenetic alterations affecting the RB1, TP53, p16INK4, and p21WAF1 tumor suppressor genes, loss of heterozygosity (LOH) at 3q and 18q, and the clinical variables of a series of Spanish children with osteosarcoma. These genetic changes were tested for an association with prognosis. METHODS: Peripheral blood samples and clinical data were available from 76 patients with osteosarcoma. Paired tissue was available from 41 of them.The mutation and methylation status of p16INK4, p21WAF1, TP53, and RB1 was screened as well as LOH at 3q and 18q. RESULTS: Loss of heterozygosity affectingRB1 (37.2%), TP53 (42.3%), and 18q (30.8%) and TP53 mutation (39%) were frequently encountered. TP53 mutation was associated with diagnosis at a later age. RB1 alteration was associated with reduced survival and event-free survival. The clinical variables associated with poor prognosis were the presence of metastasis at diagnosis (P = 0.035) or during treatment (P = 0.016) and the chondroblastic histologic subtype (P = 0.007); the response to induction chemotherapy (<90% necrosis) also tended to be related to poor prognosis (P = 0.08). CONCLUSIONS: RB1, TP53, and possibly other tumor suppressor genes locatedat 18q and other localizations are involved in pediatric osteosarcoma carcinogenesis, together with other genetic alterations not fully understood to date. Based on these results, the presence of an altered RB1 gene should be regarded as a poor prognostic factor for pediatric osteosarcoma.

BACKGROUND: The Li-Fraumeni syndrome is a relatively rare familial cancer syndrome associated with germline mutations in the tumour-suppressor gene TP53. Members of affected families can suffer from a wide variety of tumours. Identification of a germline TP53 mutation is particularly important in familiesof patients affected by one of several characteristic types of tumours. METHODS AND RESULTS: The data used for the distribution analysis of mean age at the cancer diagnosis in TP53 mutation carriers and in the Czech population were extracted from a database of 176 families (469 cancers in 346 patients) with germline TP53 mutations and from Czech statistical data of cancer incidence in years 1994 to 1998 (UZIS). The comparison of the age distribution of the relative tumour incidence in these two groups clearly separated childhood adrenocortical sarcoma, rhabdomyosarcoma, osteosarcoma and brain tumour patients. In their families genetic counselling should be recommended. CONCLUSIONS: Patients with low age at diagnosis of these tumours, particularly patients with additional personal or family history of malignancy, should be considered as potential TP53mutation carriers. It should be relevant not only for the treatment and follow-up of the patients but also for preventive measures aimed at other members of theirfamilies.

BACKGROUND: Several tumor suppressor genes such as p16INK4, TP53, RB1 y p21WAF1 are involved in cell cycle regulation in response to DNA damage and belong to the complex pathway that regulates cell proliferation and/or differentiation. We have investigated the presence of mutations in those genes and polymorphisms of Drug Metabolizing Enzymes that could be involved in the development of pediatric bonetumors or in their outcome. MATERIALS AND METHODS: By means of PCR-based techniques, we have analyzed the presence of variations in the coding sequence of p16INK4, TP53, RB1 y p21WAF1 and of the Drug Metabolizing Enzymes in a group of 82 osteosarcomas and 47 Ewing's sarcomas as well as in a control group of 115 healthy children. RESULTS: We detected mutations of the TP53 gene in about 25% of the samples analyzed, most frequently in association with tumors of poor prognosis or reduced survival. The p16INK4 gene was homozygously deleted in 18% of the osteosarcomas, also associated with poor prognosis and unfavourable histologic subtypes; RB1 was altered in 21% of the osteosarcomas. We did not detect relevant associations between polymorphisms of the Drug Metabolizing Enzymes or mutation of the p21WAF1 and development of pediatric bone tumors. CONCLUSIONS: Alteration of TP53, p16INK4 and p21WAF1 seems to be involved in thedevelopment of pediatric bone tumors and to be an unfavourable prognostic factorin this type of tumors.

Medulloblastoma is the most common malignant pediatric brain tumor. In mice, Ptc1 haploinsufficiency and disruption of DNA repair (DNA ligase IV inactivation) or cell cycle regulation (Kip1, Ink4d, or Ink4c inactivation), in conjunction with p53 dysfunction, predispose to medulloblastoma. To identify genes important for this tumor, we evaluated gene expression profiles in medulloblastomas from thesemice. Unexpectedly, medulloblastoma expression profiles were very similar among tumors and also to those of developing cerebellum. However, 21 genes were specifically up-regulated in medulloblastoma, including sFrp1, Ptc2, and Math1, members of signaling pathways that regulate cerebellar development. Coordinated deregulation of these same genes also occurred in a large subset of human medulloblastomas. These data identify a group of genes that is central to medulloblastoma tumorigenesis.

PURPOSE: This study was conducted to investigate the incidence of ERBB1 amplification and overexpression in samples of diffusely infiltrative (WHO grades II-IV) pediatric brain stem glioma (BSG) and determine the relationship of theseabnormalities to expression and mutation of TP53 and tumor grade. EXPERIMENTAL DESIGN: After central pathology review, the incidence of ERBB1 amplification andoverexpression was determined in 28 samples (18 surgical biopsy and 10 postmortem specimens) of BSG using quantitative PCR and immunohistochemistry, respectively.mutation and expression of TP53 were also determined in these same samples by direct sequence analysis of microdissected tumor material and immunohistochemistry, respectively. ALL experimental procedures were performed blind to tumor grade. RESULTS: Twelve, 9, and 7 tumors were classified as WHO grades II, III, and IV, respectively. A significant increase in ERBB1 expressionwas observed with increasing tumor grade (P < 0.001). Two grade IV tumors displayed intense membranous ERBB1 expression in 90% of tumor cells in association with high-level ERBB1 gene amplification. One grade III tumor also contained low-level amplification of ERBB1. Six tumors demonstrated TP53 nuclearimmunoreactivity, and six contained a mutation in TP53. No correlation was observed between abnormalities in TP53 and either tumor grade or amplification and overexpression of ERBB1. CONCLUSIONS: These data suggest that ERBB1 signaling is important for the development of childhood BSG and is worthy of study as a therapeutic target in this disease. Our data also indicate that the genetics of childhood BSG are complex and include both grade-dependent amplification and overexpression of ERBB1 and grade-independent expression and mutation of TP53.

Burkitt's lymphomas (BLs) are characterized by an activated MYC gene that provides a constitutive proliferative signal. However, activated myc can initiate ARF-dependent activation of p53 and apoptosis as well. Data derived from cell culture and animal models suggest that the inactivation of the ARF-MDM-2-p53 apoptotic signaling pathway may be a necessary secondary event for the development of BL. This has not been tested in freshly excised BL tissue. We investigated the ARF-MDM-2-p53 pathway in tumor specimen from 24 children with sporadic BL/B-ALL. Direct sequencing revealed a point mutation in the p53 gene in four BL. Overexpression of MDM-2 was evident in 10 of the BL samples analyzed byreal-time quantitative PCR. Deletion of the CDKN2A locus that encodes ARF or reduced expression of ARF could not be detected in any BL by fluorescence in situ hybridization analysis or real-time quantitative PCR, respectively. Our results indicate that the ARF-MDM-2-p53 apoptotic pathway is disrupted in about 55% of the cases of childhood sporadic BL. We suggest that in addition to the inactivation of the ARF-MDM-2-p53 protective checkpoint function other antiapoptotic mutations may occur in a substantial part of children with sporadic BL.

A 23-year-old woman presented with a 7 cm right multicystic mass in the ovary, which corresponded microscopically to an unusual lesion consisting of a multifocal granulosa cell tumor with intrafollicular ('in situ') growth involving two-thirds of mature follicles. Stromal invasion was found in only one area where neoplastic follicles coalesced. Granulosa cells had atypical, bizarre TP53 positive nuclei with hyperchromatism, abundant mitoses and numerous hyaline globules. The contralateral ovary was normal. From the age of 10 years, the patient had a complex medical history of multiple tumors, including telangiectatic osteosarcoma, typical and malignant phyllodes tumor, reticulohistiocytoma of skin, carcinomas of the breast and lipo- and leiomyosarcoma. The female genital tract also harbored myometrial leiomyomas andan early endometrial carcinoma. Retrospective histologic study of ALL mesenchymal neoplasms in this patient showed, the conspicuous presence of similar bizarre TP53 positive cells with hyaline globules in ALL the mesenchymal neoplasms. In the genetic study, a germline p53 gene mutation was detected in exon 10, codon 336, generating a stop codon in the oligomerization domain of the protein (E336X). A further p53 mutation was found in exon 7 in the granulosa cell tumor.mutation occurred de novo since there was no history of tumors in any family members, ALL of whom had a wild-type p53. Although this patient shows a typical tumor phenotype of Li Fraumeni syndrome, the germline mutation corresponded to ahighly unusual mutated domain, which is similar to the one found in childhood malignant adrenocortical tumor; also a rare neoplasm that originates in adrenocortical cells; which are closely related, both functionally and embryologically, to granulosa cells.#CI- Copyright 2004 USCAP, Inc.

tumor suppressor gene p53 is one of the most specific genetic alterations occurring in osteosarcoma pathogenesis. It is thought to be an early and key step in the tumorigenesis of osteosarcoma. However, whether the p53 status is a marker predictive of response to therapy and a marker of prognostic value remains controversial. The choice of p53 status detection method certainly account for discrepancies. The authors used a simple functional assay (functional analysis of separated alleles in yeast) on the tumor sample of an 8-year-old girl presentingwith an osteosarcoma of the tibia. While making it possible to exclude the presence of a germline mutation, FASAY indicated the presence of a somatic p53 mutation lacking transcriptional activity on p21 and bax target genes. FASAY also strongly suggested a loss of heterozygosity p53, which was confirmed by cytogenetic analysis. Sequencing of cDNA extracted from yeast colonies containing mutated p53 identified a 213 stop mutation in exon 6. Despite these p53 alterations, the child is still in complete remission after a follow-up of 48 months.

BACKGROUND: The p53 tumor suppressor gene is affected in a wide range of human cancers, including hematological malignancies. This gene encodes a nuclear phosphoprotein p53, which plays a key role in cell cycle arrest, induction of apoptosis, and DNA repair. mutations of the p53 gene often lead to the accumulation of the mutated protein in the nucleus of neoplastic cells. However,p53 protein expression is frequently detected in non-Hodgkin lymphomas (NHL) without any correlation with p53 mutations. This discordance suggests the existence of other mechanisms to stabilize the p53 protein, including binding ofp53 protein to viral proteins. p53 protein has been shown to bind to proteins encoded by the Epstein-Barr virus (EBV). PROCEDURE: The aim of this study was toanalyze p53 expression in childhood B-NHL and correlate its expression in the absence of p53 mutations with EBV in order to investigate a possible involvementof EBV in p53 stabilization. DESIGNS AND METHODS: tumor specimens from 35 children with B-NHL were analyzed by immunohistochemistry (IHC) with the DO7 monoclonal antibody, which recognizes an epitope at N-terminus of p53 protein and reacts with wild type and mutant proteins. To detect p53 mutations, PCR/SSCP andsequencing were performed. EBV status was determinated using a specific PCR technique. RESULTS: The overall frequency of p53 immunostaining positivity was 45% (16 of 35). p53 mutations were detected in nine patients (25.6%). p53 immunoreactivity was observed in ALL cases with mutations. Additionally, we identified 7 p53 positive cases among 26 tumors without mutations. EBV DNA was detected in 24 of 35 cases. Four patients with p53 expression dissociated from mutation were EBV positive. No statistically significant association was found between p53 expression and EBV cases despite the exclusion of those patients in which p53 expression was related with p53 mutations (P = 0.28 and 0.54, respectively). CONCLUSIONS: Our results suggested that in childhood B-NHL, the expression of p53 dissociated from mutations could not be related to EBV infection. Further studies with larger patient sets will be necessary to determinate if EBV-encoded protein may play a role for nuclear accumulation of p53 protein.#CI- Copyright 2004 Wiley-Liss, Inc.

One major factor hindering progress of pediatric cancers of the nervous system has been the lack of satisfactory model systems for testing novel therapies. A mouse strain, mutant for the Rb1 gene was generated 12 years ago in the hope of producing a model in which to study retinoblastoma. Surprisingly, the Rb(+/-) mice never developed retinoblastoma. Now, Zhang, Schweers and Dyer produce triply deficient Rb, p107 and p53 mutant retinal progenitor cells. ALL such mice develop intraocular retinoblastoma with invasion of the tumor into the anterior chamber of the eye. This dramatic finding represents the first description of a heritable mouse model of retinoblastoma, which has eluded investigators for the last 12 years. Such models provide an unprecedented opportunity to advance knowledge of tumorigenesis and to develop non-toxic intervention strategies which eradicate disease.

pediatric neurogenic tumors include primitive neuroectodermal tumors (PNETs), especially medulloblastoma; ependymomas and choroid plexus papillomas; astrocytomas; retinoblastoma; and sympathetic neuroblastoma. Meningiomas and nerve sheath tumors, although uncommon in childhood, are also significant because they can result from exposures of children to ionizing radiation. Specific chromosomal loci and specific genes are related to each of these tumor types. Virtually ALL these genes appear to act as tumor suppressor genes, which are inactivated in tumor cells by mutations or by chromosomal loss. In genetically engineered mice, some genes that are clearly associated with specific human tumors (e.g., RB1 in retinoblastoma and NF2 in meningiomas and schwannomas) haveno such effect. Other genetic constructs in mice involving the genes p53, ptc1, and Nf1 have produced tumors remarkably similar to some of the human pediatric neoplasms. Some of these tumors become clinically apparent after only a few weeks, while the mice are still juveniles, especially when two or more tumor suppressor genes are inactivated in the same genetic construct. Conversely, at least one genetic pathway in rodents involving point mutation in the coding region of a transforming gene (neu in malignant schwannomas) does not appear to operate in any human tumors. The nervous system is markedly susceptible to experimental carcinogenesis during early life in rodents, dogs, primates, and other nonhuman species, and there is no obvious reason why this generalization should not also apply to humans. However, except for therapeutic ionizing radiation, no physical, chemical, or biological cause of human pediatric nervoussystem tumors is known. The failure of experimental transplacental carcinogenesis to mirror human pediatric experience more closely may reflect the need for multiple mutational events in target cells, and for experimental carcinogens that are capable of causing the full spectrum of mutations that occur in cancer-related genes in pediatric neurogenic tumors.

Neuroblastoma is characterised by a lack of TP53 mutations and no other tumour suppressor gene consistently inactivated has yet been identified in this childhood cancer form. Characterisation of a new gene, denoted APITD1, in the neuroblastoma tumour suppressor candidate region in chromosome 1p36.22 reveals that APITD1 contains a predicted TFIID-31 domain, representing the TATA box-binding protein-associated factor, TAF(II)31, which is required for p53-mediated transcription activation. Two different transcripts of this gene were shown to be ubiquitously expressed, one of them with an elevated expressionin foetal tissues. Primary neuroblastoma tumours of ALL different stages showed either very weak or no measurable APITD1 expression, contrary to the level of expression observed in neuroblastoma cell lines. A reduced pattern of expressionwas also observed in a set of various tumour types. APITD1 was functionally tested by adding APITD1 mRNA to neuroblastoma cells, leading to the cell growth to be reduced up to 90% compared to control cells, suggesting APITD1 to have a role in a cell death pathway. Furthermore, we determined the genomic organisation of APITD1. Automated genomic DNA sequencing of the coding region of the gene as well as the promoter sequence in 44 neuroblastoma tumours did not reveal any loss-of-function mutations, indicating that mutations in APITD1 is not a common abnormality of neuroblastoma tumours. We suggest that low expression of this gene might interfere with the ability for apoptosis through the p53 pathway.

The goal of this review is to demonstrate the effective interaction of epidemiologic methods and molecular genetics in the identification of familial cancer predisposition. The example involves a hospital-based population of childhood soft tissue sarcoma patients who were less than age 16 years at diagnosis at the University of Texas M. D. Anderson cancer Center, Houston, Texas, in 1944 through 1976, had survived at least 3 years from diagnosis, and were diagnosed at least 5 years before the start of our study. Familial data were collected on the patients' offspring, full siblings, parents, aunts, uncles, andgrandparents. The initial analysis revealed a small but significant cancer excess in first-degree relatives. Genetic analysis demonstrated that the cancer distribution in families could best be explained by a rare autosomal dominant gene with penetrance such that the risk of cancer by age 35 years was nearly 50%. Most of the evidence for a dominant gene came from nine kindreds. Laboratory investigation of fibroblasts from those kindreds provided an in vitro model of cellular immortalization and carcinogenesis. Germline mutations in the tumor suppressor gene p53 were found in two of the families, and studies are ongoing in the other kindreds. This review demonstrates the power of genetic epidemiologic methods to characterize statistically a cancer-predisposing gene and the application of molecular genetics to define the genetic defect.

The p53 gene was examined in primary or metastatic tumors from six patients withrhabdomyosarcoma (RMS) and in five RMS cell lines by screening methods includingsingle-strand conformation polymorphism analysis, the RNase protection assay, sequencing of complementary DNA subclones, and Southern blotting. Six original tumors were of embryonal histology, four alveolar, and one mixed. p53 mutations were identified in four of the six tumors or cell lines derived from tumors withembryonal histology and in one of the four with alveolar histology. Consistent with p53 allele loss, each mutation was found in the homo- or hemizygous state. One tumor showed a G to C transversion at p53 codon 213 (arginine to proline), and another showed deletion of the entire gene. The p53 mutations in cell lines included a codon 248 C to T transition (arginine to tryptophan) in RD and a codon 280 A to T transversion (arginine to serine) in RH30. The cell line CTR contained a 4-base pair deletion at codons 219/220 in exon 6 with resultant frame shift and premature termination in exon 7. These data support the role of diverse types ofp53 mutations in the pathogenesis and/or progression of a significant proportionof cases of childhood RMS.

In the wake of recent progress in understanding the genetic pathways involved inthe development of brain tumors, a major goal is to correlate molecular data with clinical outcome, survival, and response to treatment modalities. This is of particular importance among the pediatric population. Reliable prognostic factors could potentially permit a tailoring of therapy in that only patients with the most aggressive tumors would receive the most intense treatments. A survey of publications about prognosis-related molecular features among pediatric brain tumors revealed 74 series, of which 46 presented statistically significant outcome-associated parameters as defined by a p value <0.05. Most investigationsrevealing significant prognosis-related features were performed on medulloblastomas (34 publications), followed by astrocytic tumors (6 publications) and ependymomas (5 publications). Promising approaches and molecular markers include gene expression profiles, DNA ploidy, loss of heterozygosity and chromosomal aberrations as detected by CGH and FISH (1q, 17p,17q), as well as oncogenes/ tumor suppressor genes and their proteins (TP53, PTEN, c-erbB2, N-myc, c-myc), growth factor and hormonal receptors (PDGFRA, VEGF, EGFR, HER2, HER4, ErbB-2, hTERT, TrkC), cell cycle genes (p27) and cell adhesionmolecules, as well as factors potentially related to therapeutic resistance (multi-drug resistance, DNA topoisomerase IIalpha, metallothionein, P-glycoprotein, tenascin). This review discusses the predictive potential of molecular markers for clinical outcome and their influence on therapeutic decision-making among children with brain tumors.

BACKGROUND: Acquired mutations in the p53 tumor-suppressor gene have been detected in several human cancers, including colon, breast, and lung cancer. Inherited mutations (transmitted through the germline) of this gene can underliethe Li-Fraumeni syndrome, a rare familial association of breast cancer in young women, childhood sarcomas, and other malignant neoplasms. We investigated the possibility that p53 mutations in the germline are associated with second primary cancers that arise in children and young adults who would not be considered as belonging to Li-Fraumeni families. METHODS: Genomic DNA was extracted from the blood leukocytes of 59 children and young adults with a second primary cancer. The polymerase chain reaction, in combination with denaturant-gel electrophoresis and sequencing, was used to identify p53 gene mutations. RESULTS: mutations of p53 that changed the predicted amino acid sequence were identified in leukocyte DNA from 4 of the 59 patients (6.8 percent). In three cases, the mutations were identical to ones previously found in the p53 gene. The fourth mutation was the first germline mutation to be identified in exon 9, at codon 325. Analysis of leukocyte DNA from close relatives of three of the patients indicated that the mutations were inherited, but cancer had developed in only one parent at the start of the study. CONCLUSIONS: These findings identify an important subgroup of young patients with cancer who carry germline mutations in the p53 tumor-suppressor gene but whose family histories are not indicative of the Li-Fraumeni syndrome. The early detection of such mutations would be useful not only in treating these patients, but also in identifying family members who may be at high risk for the development of tumors.

Neuroblastoma is a pediatric tumor accounting for 15% of childhood cancer deathsand has a poor prognosis in children >1 year of age. We investigated the abilityof apigenin, a nonmutagenic dietary flavonoid that has been shown to have antitumor effects in various tumor cell lines, to inhibit growth and induce apoptosis of the human neuroblastoma cell lines NUB-7, LAN-5, and SK-N-BE(2). Apigenin inhibited colony-forming ability and survival, and induced apoptosis ofNUB-7 and LAN-5 cells. The presence of the C2-C3 double bond and the 4'-OH groupon the flavonoid structure correlated with the growth-inhibitory potential of apigenin. Furthermore, apigenin inhibited NUB-7 xenograft tumor growth in anonobese diabetic/severe combined immunodeficiency mouse model, likely by inducing apoptosis. Apigenin did not inhibit survival of primary sympathetic neurons, suggesting that it is not toxic to nontransformed cells. The mechanism of action of apigenin seems to involve p53, as it increased the levels of p53 and the p53-induced gene products p21WAF1/CIP1 and Bax. Furthermore, apigenin (15-60micromol/L) induced cell death and apoptosis of neuroblastoma cells expressing wild-type but not mutant p53. Apigenin increased caspase-3 activity and PARP cleavage, and Z-VAD-FMK, a broad-spectrum caspase-3 inhibitor, rescued NUB-7 cells from apigenin-mediated apoptosis indicating that apigenin induced apoptosis in acaspase-dependent manner. Overexpression of Bcl-X(L) rescued NUB-7 from apigenin-induced cell death, suggesting that Bax activity is important for the action of apigenin. Apigenin is thus a candidate therapeutic for neuroblastoma that likely acts by regulating a p53-Bax-caspase-3 apoptotic pathway.

BACKGROUND: Brainstem tumors represent 10% of central nervous system tumors, accounting for 30% of pediatric posterior fossa tumors. AIMS: The aim of this study was to clinicopathologically correlate 45 cases of brain stem gliomas and determine the occurrence and prognostic significance of p53 expression. MATERIALS AND METHOD: 45 cases of brain stem gliomas encountered during a 19-year period. 30 were diagnosed by surgical biopsy and 15 at autopsy. In 25 cases p53 immunohistochemistry (Avidin Biotinylated technique) was performed. The WHO brain tumor classification and Stroink's CT classification were applied. STATISTICAL ANALYSIS USED: Chi square test. RESULTS AND CONCLUSIONS: 51 % of gliomas were observed in the first decade of life. The female to male ratio was 1.04: 1. The commonest presenting features were cranial nerve palsies (33%) and cerebellar signs (29.8%). 55.55% of cases were located in the pons, 31.01% in the medulla and 13.33% in the midbrain. Diffuse astrocytomas were seen in 40 cases (5% were Grade I, 47.5%Grade II, 32.5% Grade III and 15% Grade IV) and pilocytic astrocytomas in 5 cases. Grade IV patients had 2- 3 mitoses /10 high power fields and had a poorer survival rate. Grade II astrocytomas were treated with excisionand radiotherapy, while grade III and IV tumors were treated with radiotherapy and chemotherapy (CCNU). Improvement was noted in 20% of patients postoperatively. The outcome was better in patients who were treated surgically.p53 is a frequently mutated gene in brain stem astrocytomas. It was found in 50 % of glioblastoma multiforme, 28.57% of grade III astrocytoma and 12.5% of grade II astrocytoma, while grade 1 astrocytomas failed to express p53 protein. p53 positivity was more in high grade lesions, decreasing significantly in lower grade lesions.

BACKGROUND: Germ-line p53 mutations appear to be inherited among the members of families diagnosed with Li-Fraumeni syndrome (LFS). The mutations detected in those families to date have been clustered in exon 7 of the p53 gene and, typically, have been single-base substitutions resulting in amino acid changes. PURPOSE: Our aim was to define the spectrum of p53 mutations associated with LFS. METHODS: From seven cancer-prone families identified by selecting members with childhood adrenocortical carcinoma as probands, we chose two families, each of which had two members from whom specimens could be obtained for genetic analysis. To detect germ-line p53 gene mutations in these individuals, we performed polymerase chain reaction (PCR)-single-strand conformation polymorphism analysiswith Taq polymerase and oligonucleotide primers specific for p53 gene sequences.Genomic DNA extracted from fresh tissue samples and paraffin-embedded tumor samples was amplified, denatured, and electrophoresed on neutral polyacrylamide gels. PCR amplification was also carried out using total RNA from adrenocorticalcarcinoma samples of the proband in family 1. PCR products were purified, subcloned, and sequenced. RESULTS: We detected novel germ-line p53 mutations in affected members of both cancer-prone families. In the proband of family 1, a single-base deletion was detected at the first nucleotide of codon 307 in exon 8of the p53 gene, resulting in a premature stop codon in exon 10. In family 2, wedetected an A to C transversion at the second nucleotide of codon 286 in exon 8,both in DNA isolated from the adrenocortical tumor of the proband and in DNA isolated from the astrocytoma of the proband's father. This single-base substitution resulted in an amino acid substitution of alanine for glutamic acid. Both of these mutations are located outside the highly conserved region of the p53 gene where mutations in patients with LFS have been reported previously. CONCLUSION: Our results indicate that a wide range of germ-line p53 mutations isinherited in members of diverse-cancer-prone families.

BACKGROUND: Germ-line p53 mutations appear to be inherited among the members of families diagnosed with Li-Fraumeni syndrome (LFS). The mutations detected in those families to date have been clustered in exon 7 of the p53 gene and, typically, have been single-base substitutions resulting in amino acid changes. PURPOSE: Our aim was to define the spectrum of p53 mutations associated with LFS. METHODS: From seven cancer-prone families identified by selecting members with childhood adrenocortical carcinoma as probands, we chose two families, each of which had two members from whom specimens could be obtained for genetic analysis. To detect germ-line p53 gene mutations in these individuals, we performed polymerase chain reaction (PCR)-single-strand conformation polymorphism analysiswith Taq polymerase and oligonucleotide primers specific for p53 gene sequences.Genomic DNA extracted from fresh tissue samples and paraffin-embedded tumor samples was amplified, denatured, and electrophoresed on neutral polyacrylamide gels. PCR amplification was also carried out using total RNA from adrenocorticalcarcinoma samples of the proband in family 1. PCR products were purified, subcloned, and sequenced. RESULTS: We detected novel germ-line p53 mutations in affected members of both cancer-prone families. In the proband of family 1, a single-base deletion was detected at the first nucleotide of codon 307 in exon 8of the p53 gene, resulting in a premature stop codon in exon 10. In family 2, wedetected an A to C transversion at the second nucleotide of codon 286 in exon 8,both in DNA isolated from the adrenocortical tumor of the proband and in DNA isolated from the astrocytoma of the proband's father. This single-base substitution resulted in an amino acid substitution of alanine for glutamic acid. Both of these mutations are located outside the highly conserved region of the p53 gene where mutations in patients with LFS have been reported previously. CONCLUSION: Our results indicate that a wide range of germ-line p53 mutations isinherited in members of diverse-cancer-prone families.

Nucleophosmin (NPM) is a nucleocytoplasmic shuttling protein involved in leukemia-associated chromosomal translocations, and it regulates the alternate reading frame (ARF)-p53 tumor-suppressor pathway. Recently, it has been demonstrated that mutations of the NPM1 gene alter the protein at its C-terminal, causing its cytoplasmic localization. Cytoplasmic NPM was detected in 35% of adult patients with primary non-French-American-British (FAB) classification M3 acute myeloid leukemia (AML), associated mainly with normal karyotype. We evaluated the prevalence of the NPM1 gene mutation in non-M3 childhood AML patients enrolled in the ongoing Associazione Italiana di Ematologia e Oncologiapediatrica (AIEOP-AML02) protocol in Italy. NPM1 mutations were found in 7 (6.5%) of 107 successfully analyzed patients. NPM1-mutated patients carried a normal karyotype (7/26, 27.1%) and were older in age. Thus, the NPM1 mutation is a frequent abnormality in AML patients without known genetic marker; the mutation may represent a new target to monitor minimal residual disease in AML and a potential candidate for alternative and targeted treatments.

In the past year we have witnessed significant progress in understanding the molecular basis of cancerogenesis and in identifying the genetic determinants ofsusceptibility to cancer. In particular, the finding that the same tumor suppressor genes play a pathogenic role in both the inherited and the sporadic forms of some childhood tumors has suggested that this gene class may also be involved in adult tumors derived from inherited familial cancer syndromes. The identification of the gene defect underlying the Li-Fraumeni syndrome, a germline mutation of the tumor suppressor gene p53, has fully confirmed that suggestion. Three other genes associated with the inherited cancer syndromes neurofibromatosis type I (NF-1) and familial adenomatous polyposis have been cloned and partially characterized. In addition to these genes, which have a relatively high penetrance and contribute directly to tumorigenesis, other genesthat lead to cancer as a secondary effect seem to act in determining an individual's overall cancer risk. The latter genes are most likely related to defective processes of DNA repair or to regulation of carcinogen metabolism. In this context the analysis of models of murine strains with different genetic susceptibility to cancer of various organs may be a useful tool for unveiling the genetic basis for cancer susceptibility in individuals.

In the past year we have witnessed significant progress in understanding the molecular basis of cancerogenesis and in identifying the genetic determinants ofsusceptibility to cancer. In particular, the finding that the same tumor suppressor genes play a pathogenic role in both the inherited and the sporadic forms of some childhood tumors has suggested that this gene class may also be involved in adult tumors derived from inherited familial cancer syndromes. The identification of the gene defect underlying the Li-Fraumeni syndrome, a germline mutation of the tumor suppressor gene p53, has fully confirmed that suggestion. Three other genes associated with the inherited cancer syndromes neurofibromatosis type I (NF-1) and familial adenomatous polyposis have been cloned and partially characterized. In addition to these genes, which have a relatively high penetrance and contribute directly to tumorigenesis, other genesthat lead to cancer as a secondary effect seem to act in determining an individual's overall cancer risk. The latter genes are most likely related to defective processes of DNA repair or to regulation of carcinogen metabolism. In this context the analysis of models of murine strains with different genetic susceptibility to cancer of various organs may be a useful tool for unveiling the genetic basis for cancer susceptibility in individuals.

Polymorphisms in codon 72 of the p53 tumor suppressor gene have been associated with susceptibility to human cancer. We wished to evaluate whether variant allelic forms of the p53 protein were associated with brain tumors. In this study, we scored 135 brain tumor samples (92 adult and 43 pediatric cases consisting of 64 high-grade astrocytomas and 71 non-astrocytomas) for the P53 Arg72Pro polymorphisms. Our data show that the genotype frequencies of P53 Arg72Pro vary not only between patients with brain tumors and controls, but alsobetween different histological subtypes of brain tumors. Specifically, we found (i) that the genotype distributions of the P53 Arg72Pro between ALL brain tumorsand controls were statistically significant (P < 0.001) as well as their variantallele frequencies between cases and controls (P < 0.001); (ii) that there was asignificant increase in the Arg/Pro heterozygous genotype among high-grade astrocytomas compared with non-astrocytomas (P = 0.002); and (iii) that there was a significant increase in the Arg/Pro heterozygous genotype among high-grade astrocytomas containing transdominant as well as recessive p53 mutations compared with controls (P = 0.002). Our results suggest a possible association between P53 Arg72Pro polymorphisms and susceptibility to brain tumors, particularly high-grade astrocytomas.

Infection with hepatitis viruses and chronic exposure to high levels of dietary aflatoxins are the major etiologic agents for hepatocellular carcinoma in west Africa. A challenge for the prevention of hepatocellular carcinoma in this region is that both hepatitis B virus and aflatoxin exposures start early in life; indeed, aflatoxin exposures can start in utero and continue unabated throughout childhood. A mutation in the TP53 tumor suppressor gene at codon 249 (TP53 Ser249 mutation) has been reported previously for hepatocellular carcinoma tumors and matched plasma DNA samples in individuals from areas with high aflatoxin exposure. We examined whether the TP53 Ser249 mutation could be observed in DNA found in plasma of young children (ages 2-5 years) from Guinea, west Africa, a region of high aflatoxin exposure. Plasma aflatoxin-albumin adducts were presentin 119 of 124 (96%) of the children, geometric mean of positives 9.9 pg/mg albumin (95% confidence interval, 8.8-11.0 pg/mg). This is the level and prevalence of exposure observed previously in adults. Following PCR amplification of plasma-derived DNA and detection using mass spectrometry, none of the sampleswere found to contain the TP53 Ser249 mutation. Because approximately 50% of thehepatocellular carcinomas in adults in west Africa have this specific TP53 Ser249 mutation, a lack of detection in samples from children ages <5 years may indicate that a window of opportunity for intervention exists that could be exploited to lower hepatocellular carcinoma risk.

Genetic anticipation is the increased incidence, earlier onset, or increased severity of a disease in successive generations. Before the biological basis of anticipation had been demonstrated, the phenomenon was thought to be due to sampling bias, epigenetic effects, gene conversion, or recombinant events. Sincethen, the biologic basis for anticipation in a number of neurodegenerative disorders has been shown to be attributable to trinucleotide repeat instability,with expansion of repeats clearly correlated with an earlier age of onset. Recently, telomere shortening has been suggested as the mechanism for anticipation in the autosomal dominant form of dyskeratosis congenita, attributable to mutations in the TERC gene, leading to dysfunctional telomeres (Vulliamy et al. 2004). However, the pattern of anticipation has been observed in other disorders, including cancers, for which no genetic defect has been identified. In this study, we assess the apparent generation effect on cancer incidence in ten extended families with P53 germline mutation, identified through probands diagnosed with childhood sarcoma. The probands were from two sets of systematically ascertained sarcoma patients treated at the University of Texas M. D. Anderson cancer Center between 1944 and 1982. From those overall studies, we have identified ten kindreds having germline P53 mutations in more than one generation. We compared the cancer incidence in members of successive generations of these families with P53 mutations (carriers) and with no P53 mutations (noncarriers). In carriers, cancer incidence increased in succeeding generations; there was no evidence for this effect in noncarriers; however, the noncarrier population was too small to rule it out. The apparent lack of increase in incidence in noncarriers argues against a cohort effect explaining the increase in carriers.

pediatric glioblastoma multiforme (GBM) tumors, which have been established as 'de novo' neoplasms, are known to differ from their adult counterparts in terms of biology, genetics and ultimately survival of patients. In order to evaluate the utility of markers of tumor biology for refining prognostic assessment, we retrospectively analyzed 54 pediatric GBMs (age range 9 months to 15 years) occurring at different anatomical sites in the brain, operated at our institute between 1995 and 2001. The expression of p53, epidermal growth factor receptor (EGFR), bcl-2 and retinoblastoma proteins (pRb) was analyzed by immunohistochemistry and the results were compared with the clinical profile, MIB-1 labeling index (LI) and patient survival. p53 immunoreactivity was noted in 53.7% of cases, predominantly in thalamic (75%) and cerebral lobar (62.2%), followed by brainstem tumors (30%). It was absent in cerebellar tumors. p53-positive tumors had a higher MIB-1 LI, compared to p53-negative tumors (p=0.003). EGFR and bcl-2 overexpression was observed in 25.9% and 33.3% of cases, respectively, and loss of pRb expression was evident in only 7.4% of cases, indicating that loss of this gene function is not significantly involved in pediatric GBMs. p53 and bcl-2 expression were maximally noted in patients with poorer outcome. Our results indicate that p53 expression status is noted in a significant number of pediatric supratentorial neoplasms. p53 with bcl-2 overexpression is more often associated with ominous prognosis. Further molecular characterization would provide newer insights into the biology of these neoplasms and form a basis for future therapeutic decision making.#CI- Copyright (c) 2005 S. Karger AG, Basel.

We have analyzed the regulation and expression of ASPP members, genes implicatedin the regulation of the apoptotic function of the TP53 tumor-suppressor gene, in acute lymphoblastic leukemia (ALL). expression of ASPP1 was significantly reduced in ALL and was dependent on hypermethylation of the ASPP1 gene promoter. Abnormal ASPP1 expression was associated with normal function of the tumor-suppressor gene TP53 in ALL. The analyses of 180 patients with ALL at diagnosis showed that the ASPP1 promoter was hypermethylated in 25% of cases with decreased mRNA expression. Methylation was significantly higher in adult ALL vs childhood ALL (32 vs 17%, P = 0.03) and T-ALL vs B-ALL (50 vs 9%, P = 0.001). Relapse rate (62vs 44%, P = 0.05) and mortality (59 vs 43%, P = 0.05) were significantly higher in patients with methylated ASPP1. DFS and OS were 32.8 and 33.7% for patients with unmethylated ASPP1 and 6.1 and 9.9% for methylated patients (P < 0.001 y P < 0.02, respectively). On the multivariate analysis, methylation of the ASPP1 genepromoter was an independent poor prognosis factor in ALL patients. Our results demonstrate that decreased expression of ASPP1 in patients with ALL is due to anabnormal methylation of its promoter and is associated with a poor prognosis.

Pilocytic astrocytomas are the most frequent gliomas of childhood. The majority of cases show cytogenetic normal karyotypes. Although in diffuse gliomas TP53 gene mutations or deletions occur with significant frequency, the role in pilocytic astrocytomas remains unclear. Histomorphologically different areas of 14 pilocytic astrocytomas were microdissected and analyzed for genetic aberrations and heterogeneity. CGH analysis revealed gains of chromosome arm 4q and 6q mainly in areas of classic biphasic pattern, whereas pleomorphic areas presented gains of chromosome 6 and 8q. Using two-color fluorescence in situ hybridization (FISH) the spatial distribution of aneuploidies for chromosomes 7,8, 17 and the TP53 gene were assessed on parallel sections. FISH analysis revealed a significant percentage of cells with interspersed heterozygous deletions of TP53 in ALL tumors (14/14), ten cases showed also monosomy 17. Besides gains of chromosomes 7 and 8, losses of these chromosomes were detected in the majority of tumors. In conclusion, pilocytic astrocytomas show a genetic heterogeneity associated with variations of histologic structure as well as an intratumoral heterogeneity observed on single cell level by FISH.

This paper presents the analysis of familial cancer data collected in a hospital-based study of 159 childhood soft-tissue-sarcoma patients. Two different statistical models detected excess aggregation of cancer, which could be explained by a rare dominant gene. For each kindred, we estimated the probability of the observed cancer distribution under the dominant-gene model and identified12 families that are the most likely to be segregating the gene. Two of those families have confirmed germ-line mutations in the p53 tumor-suppressor gene. The relative risk of affection for children who are gene carriers was estimated to be 100 times the background rate. Females were found to have a slightly higher age-specific penetrance, but maternal and paternal lineages made equal contributions to the evidence in favor of the dominant gene. The proband's histology, ethnicity, and age at diagnosis were evaluated to determine whether any of these altered the probability of affection in family members. Only embryonal rhabdomyosarcoma was found to be a significant covariate under the dominant-gene model. While molecular genetic studies of familial cancer will eventually provide answers to the questions of genetic heterogeneity, age- and site-specific penetrance, mutation rates, and gene frequency, information from statistical models is useful for setting priorities and defining hypotheses.

Ewing sarcoma (ES), a highly malignant pediatric tumor, is consistently associated with translocations that fuse the EWS gene with a member of the ETS family gene, most commonly FLI-1. Despite significant advances with multiagent chemotherapy, surgery and radiotherapy, about 40% of ES patients still die from the disease. It is therefore necessary to explore novel agents for possible treatment of this tumor. Here the authors investigated the sensitivity of ES cells to clinically tolerable concentrations of arsenic trioxide (As2O3), a compound known to induce differentiation and apoptosis of other types of malignant cells. The authors report that As2O3 uniformly induced death of 6 ES-derived cell lines irrespective of their p53 status. As2O3 resulted in an apoptotic phenotype which was inhibited by the broad-spectrum caspase inhibitor ZVAD-fmk. These effects correlated with prolonged c-jun N-terminal kinase activation, which is a signal for apoptosis in ES cells. As2O3 also decreased basal and cytokine-induced NF-kappa B activity. Since the authors previously demonstrated that NF-kappa B exerts an antiapoptotic action in ES cells, As2O3 treatment may also result in a sensitization of these cells to other drugs used in combination therapy. These effects, combined with its antiangiogenic action, define As2O3 as a good candidate for future protocols to improve treatments of Ewing sarcomas, irrespective of the p53 status of the tumor.#CI- Copyright 2006 Wiley-Liss, Inc.

Hotspot mutations in the p53 tumor suppressor gene result in the disruption of DNA contact points or alter the overall structure of the protein to prevent DNA binding. When inherited, hotspot mutants are associated with Li-Fraumeni syndrome (LFS), a familial cancer predisposition. One of the most common hotspot mutations occurs at codon 175, resulting in an arginine to histidine substitution. We haveidentified a novel germ line variant of the 175 mutant (Arg to Leu; R175L) in a pediatric patient who developed adrenal cortical carcinoma. Surprisingly, the family is not tumor prone or associated with LFS. In vitro, the R175L mutant displayed an attenuated tumor suppressor activity in the regulation of transcription, colony formation, and apoptosis when compared with wild-type p53 and the R175H mutant. These findings suggest that p53-R175L retains sufficient activity to suppress LFS, but not adrenal cortical carcinoma. Therefore, not allhotspot mutants are functionally equivalent and the biochemical nature of the mutant may significantly influence clinical outcome. The implications of these results for genetic counseling are discussed.

Hotspot mutations in the p53 tumor suppressor gene result in the disruption of DNA contact points or alter the overall structure of the protein to prevent DNA binding. When inherited, hotspot mutants are associated with Li-Fraumeni syndrome (LFS), a familial cancer predisposition. One of the most common hotspot mutations occurs at codon 175, resulting in an arginine to histidine substitution. We haveidentified a novel germ line variant of the 175 mutant (Arg to Leu; R175L) in a pediatric patient who developed adrenal cortical carcinoma. Surprisingly, the family is not tumor prone or associated with LFS. In vitro, the R175L mutant displayed an attenuated tumor suppressor activity in the regulation of transcription, colony formation, and apoptosis when compared with wild-type p53 and the R175H mutant. These findings suggest that p53-R175L retains sufficient activity to suppress LFS, but not adrenal cortical carcinoma. Therefore, not allhotspot mutants are functionally equivalent and the biochemical nature of the mutant may significantly influence clinical outcome. The implications of these results for genetic counseling are discussed.

The p53 gene is involved in the control of cell-cycle arrest and apoptosis. The germline Arg72Pro polymorphism alters the protein's biochemical functions, and may confer individual susceptibility to skin cancer. We evaluated the association of the Arg72Pro polymorphism with skin cancer risk among Caucasians in a nested case-control study within the Nurses' Health Study (NHS) (219 melanoma, 286 squamous cell carcinoma (SCC), and 300 basal cell carcinoma (BCC) and 874 controls). Compared to the Arg/Arg genotype, the Pro/Pro genotype had an OR of 1.57 (95%CI, 0.81-3.06) for melanoma risk, and an OR of 1.79 (95%CI, 1.01-3.17) for BCC risk. The positive association of the Pro allele with BCC risk was only limited to women with two or fewer lifetime sunburns (P, trend, 0.002; P, interaction, 0.02). No association was observed between the polymorphism and SCCrisk. We also observed that the Pro allele was inversely associated with the risk of childhood sunburn among Caucasian participants pooled from four nested case-control studies within the NHS. This study suggests that the Arg72Pro polymorphism may play a role in skin carcinogenesis.

Li-Fraumeni Syndrome (LFS) is characterized by early-onset carcinogenesis involving multiple tumor types and shows autosomal dominant inheritance. Approximately 70% of LFS cases are due to germline mutations in the TP53 gene onchromosome 17p13.1. mutations have also been found in the CHEK2 gene on chromosome 22q11, and others have been mapped to chromosome 11q23. While characterizing an LFS family with a documented defect in TP53, we found one family member who developed bilateral breast cancer at age 37 yet was homozygousfor wild-type TP53. Her mother also developed early-onset primary bilateral breast cancer, and a sister had unilateral breast cancer and a soft tissue sarcoma. Cytogenetic analysis using fluorescence in situ hybridization of a primary skin fibroblast cell line revealed that the patient had a novel balancedreciprocal translocation between the long arms of chromosomes 11 and 15: t(11;15)(q23;q15). This translocation was not present in a primary skin fibroblast cell line from a brother with neuroblastoma, who was heterozygous forthe TP53 mutation. There was no evidence of acute lymphoblastic leukemia in either the patient or her mother, although a nephew did develop leukemia and died in childhood. These data may implicate the region at breakpoint 11q23 and/or 15q15 as playing a significant role in predisposition to breast cancer development.

tumors of the nervous system most often occur in both children and adults as sporadic events with no family history of the disease, but they are also among the clinical manifestations of a significant number of familial cancer syndromes, including familial retinoblastoma, neurofibromatosis 1 and 2, tuberous sclerosis, and Cowden, Turcot, Li-Fraumeni and nevoid basal cell carcinoma (Gorlin) syndromes. ALL of these syndromes involve transmissible genetic risk resulting from loss of a functional allele, or inheritance of a structurally defective allele, of a specific gene. These genes include RB1, NF1, NF2, TSC1, TSC2, TP53,PTEN, APC, hMLH1, hPSM2, and PTCH, most of which function as tumor suppressor genes. The same genes are also observed in mutated and inactive forms, or are deleted, in tumor cells in sporadic cases of the same tumors. The nature of the mutational events that give rise to these inactivated alleles suggests a possible role of environmental mutagens in their causation. However, only external ionizing radiation at high doses is clearly established as an environmental cause of brain, nerve and meningeal tumors in humans. Transplacental carcinogenesis studies in rodents and other species emphasize the extraordinary susceptibility of the developing mammalian nervous system to carcinogenesis, but the inverse relationship of latency to dose suggests that low transplacental exposures to genotoxicants are more likely to result in brain tumors late in life, rather than in childhood. While not ALL neurogenic tumor-related genes in humans have similar effects in experimental rodents, genetically engineered mice (GEM) increasingly provide useful insights into the combined effects of multiple tumor suppressor genes and of gene-environment interactions in the genesis of brain tumors, especially pediatric brain tumors such as medulloblastoma.

Basal cell carcinoma (BCC) generally has an indolent course but a subgroup of BCCs tends to grow aggressively into deep tissues and even metastasize. Althoughstudies have shown a positive correlation between mutations in the tumor suppressor gene p53 and aggressive behavior in epithelial tumors, the results for BCC are conflicting. We aimed to determine whether there is any relationship between p53 expression in BCC and histopathologic subtype of the tumor.Thirty-three formalin-fixed BCC tissue samples were examined at Hazrat-e Rasool University Hospital, Tehran, Iran, from March 2003 to April 2004. tumors were categorized as aggressive (infiltrative or morpheic) and non-aggressive (nodular or superficial) based on histopathological examination of hematoxylin and eosin sections. p53 expression was demonstrated by immunohistochemical staining using the monoclonal anti-p53 antibody (PAb240) and results were reported using a semiquantitative score. expression of p53 was compared between aggressive and non-aggressive tumors. ALL of the 11 aggressive tumors exhibited nuclear staining in more than 50% of the tumor cells. In the 22 non-aggressive tumors, less than 50% of cells showed positive staining. p53 immunoreactivity was significantly higher in aggressive BCCs than non-aggressive ones (x(2) test; p <0.01). No correlation was found between p53 expression and the age of the patient or site of the tumor. History of childhood radiotherapy correlated positively with higher levels of p53 expression. We conclude that expression of p53 might be used as a marker to predict the aggressiveness of BCCs.

BACKGROUND: Somatic and constitutional mutation screening of p53 in childhood sarcomas and retinoblastoma was investigated by a multitechnical approach to evaluate its role in the development/progression by somatic mutation events and/or genetic predisposition. MATERIAL/METHODS: The studies were carried out ona cohort of 100 sarcoma cases, i.e. Ewing's sarcoma (n=44), osteosarcoma (n=36),and rhabdomyosarcoma (n= 20), and on 50 retinoblastoma (Rb) cases. RESULTS: Constitutional allelic deletion was found by FISH in 4% of sarcoma cases. Overall, 20% of sarcoma tumors showed p53 rearrangement by PCR/SSCP and Southernblot. Allelic deletion of p53 was detected in 78% of sarcoma and 55% of Rb tumors. p53 protein expression was detected by immunohistochemistry in 20% of sarcoma tumors. CONCLUSIONS: This study for the first time provided evidence of p53 alteration through allelic deletion that are common primary somatic mutationevents which occur irrespective of grade and stage and are hence probably associated with an early phase of tumorigenesis and/or tumor progression. The studies also explored the occurrence of de novo constitutional deletion of p53 in sporadic childhood sarcomas. This study in retinoblastoma provided evidence for the synergistic role of RB1 and p53, probably essential for the full-blown development of malignancy.

BACKGROUND: Somatic and constitutional mutation screening of p53 in childhood sarcomas and retinoblastoma was investigated by a multitechnical approach to evaluate its role in the development/progression by somatic mutation events and/or genetic predisposition. MATERIAL/METHODS: The studies were carried out ona cohort of 100 sarcoma cases, i.e. Ewing's sarcoma (n=44), osteosarcoma (n=36),and rhabdomyosarcoma (n= 20), and on 50 retinoblastoma (Rb) cases. RESULTS: Constitutional allelic deletion was found by FISH in 4% of sarcoma cases. Overall, 20% of sarcoma tumors showed p53 rearrangement by PCR/SSCP and Southernblot. Allelic deletion of p53 was detected in 78% of sarcoma and 55% of Rb tumors. p53 protein expression was detected by immunohistochemistry in 20% of sarcoma tumors. CONCLUSIONS: This study for the first time provided evidence of p53 alteration through allelic deletion that are common primary somatic mutationevents which occur irrespective of grade and stage and are hence probably associated with an early phase of tumorigenesis and/or tumor progression. The studies also explored the occurrence of de novo constitutional deletion of p53 in sporadic childhood sarcomas. This study in retinoblastoma provided evidence for the synergistic role of RB1 and p53, probably essential for the full-blown development of malignancy.

Familial osteosarcoma is a rare hereditary disease. We present a 37-year-old father and a 17-year-old son who developed osteosarcoma in the left and right distal femurs, respectively, at a three-year interval. They were treated with chemotherapy followed by surgery. Both had positive immunostaining for p53 tumorsuppressor gene and HER-2/neu oncogene. The son also exhibited deletion of the retinoblastoma 1 gene. Pulmonary metastasis was detected in the father at the time of diagnosis and 13 months after primary treatment, whereas no distant metastasis was present in the child. The father died 39 months after the diagnosis from primary symptoms, but the son led a disease-free survival a year after completion of treatment. Genetic abnormalities documented in the father and son corroborate the presence of specific genetic alterations in the pathogenesisof osteosarcoma.

hSNF5/Ini1 is a core component of the SWI/SNF complex and the gene is frequentlymutated in aggressive pediatric rhabdoid tumors. Mechanisms of the malignant transformation, however, remain poorly understood. We analyzed HeLa cells treated with siRNA to the hSNF5/Ini1 mRNA. The resulting efficient and long-term suppression caused characteristic cell enlargement, cell cycle arrest in G1 phase, and subsequent modest apoptosis. Gene expression profiling of the hSNF5-down-regulated cells by cDNA microarray analysis revealed that a limited number of p53-responsive genes, especially p21, were up-regulated. The p53 protein level was also greatly enhanced, suggesting that loss of hSNF5/Ini1 induces a p53 signaling pathway irrelevant to the chk1/2 phosphorylation pathway. Some rhabdoid tumors with very low or no ARF expression were induced to undergo cell enlargement, growth arrest, and, in one case, apoptosis by ectopic expression of the p14ARF protein. These results may in part account for molecular mechanisms of rhabdoid tumor formation.

INTRODUCTION: Multiple familial cancer is a rare entity as is also Li-Fraumeni Syndrome (LFS), which involves a mutation in the germ cell line of Tp53 suppresor gene that is expressed in chromosome 17p13.1 and occurs as an autosomal dominantcondition. OBJECTIVE: Presentation of one case of LFS. CLINICAL CASE: Family history: maternal grandfather had melanoma and maternal aunt had osteoblastic osteosarcoma of the left distal femur. Eight-and-a-half year-old child with a history of a CNS tumor (choroid plexus carcinoma) and two years later, a melanoma (Spitz nevus). SYMPTOMS: impaired motor function of the left half of the body and pain upon ipsilateral gait. The physical exam showed swelling of the left iliac crest. The X-rays showed osteoblastic osteosarcoma and the fine needle aspiration biopsy (FNAB) was positive. The diagnosis was made according to the clinical criteria for LFS. DISCUSSION: We report a case of LFS diagnosed based on clinical criteria. We suggest that the questioning of patients with cancer be aimed at finding out the family history of neoplasias. The case presented herein shows anevident association between both choroid plexus carcinoma and osteoblastic osteosarcoma and the patient's family history. We think that any physician treating children with cancer should consider these multiple familial cancer syndromes.

For pediatric cancers like neuroblastoma, the most common extracranial solid tumor of infancy, p53 mutations are rare at diagnosis, but may be acquired afterchemotherapy, suggesting a potential role in drug resistance. Heavy metal-selected neuroblastoma cells were found to acquire an unusually broad multidrug resistance (MDR) phenotype but displayed no alterations in genes associated with "classic" MDR. These cells had acquired a mutant p53 gene, linking p53 to drug sensitivity in neuroblastoma. We therefore generated p53-deficient variants in neuroblastoma cell lines with wild-type p53 by transduction of p53-suppressive constructs encoding either short hairpin RNA or a dominant-negative p53 mutant. Analysis of these cells indicated that (a) in contrast to previous reports, wild-type p53 was fully functional in ALL neuroblastoma lines tested; (b) inactivation of p53 in neuroblastoma cells resulted in establishment of a MDR phenotype; (c) p53-dependent senescence, the primary response of some neuroblastoma cells to DNA damage, is replaced after p53 inactivation by mitotic catastrophe and subsequent apoptosis; (d) knockdown of mutant p53 did not revert the MDR phenotype, suggesting it is determined by p53 inactivation rather than gain of mutant function. These results suggest the importance of p53 status as a prognostic marker of treatment response in neuroblastoma. p53 suppression may have opposite effects on drug sensitivity as determined by analysis of isogenic pairs of tumor cell lines of nonneuroblastomaorigin, indicating the importance of tissue context for p53-mediated modulation of tumor cell sensitivity to treatment.

Optic pathway gliomas (OPGs) are the most common primary neoplasm of the optic pathway. These lesions usually present in childhood and can arise anywhere alongthe optic pathway; they occur more frequently in women; and they rarely undergo late progression. Management strategies after the initial diagnosis are controversial, compounded by the different behaviors exhibited by sporadic and syndromic tumors. Neurofibromatosis Type 1 (NF1), with aberrant oncogenic signaling and consequent predisposition to intracranial tumors, is the most common associated syndrome, with nearly 20% of NF1 patients developing OPGs. A comorbid NF1 diagnosis has implications for tumor location with greater predilection for optic nerve involvement, whereas chiasmal and postchiasmal lesions are more frequently seen in sporadic cases. Syndromic OPGs often exhibitmore indolent behavior and lower rates of clinical progression, and the majorityof these are diagnosed by routine neuroophthalmological screening. When treatment is indicated, however, the molecular abnormalities that constitute this syndromecan limit the available chemotherapy and radiotherapy options because cliniciansfear secondary malignancy and cerebrovascular complications. Furthermore, radiotherapy early in life can impair an individual's intellectual development, endocrine function, and physical growth, thereby limiting the role of this modality in the treatment of this childhood lesion. Differential gene expressionand histogenesis among sporadic and syndromic OPGs may account for the differenttumor behaviors, but studies correlating specific genetic and proteomic changes with patient outcome are pending. Loss of heterozygosity at 10 and 17q are more common among patients with NF1, and Ki67 labeling intensity of 2-3% and low p53 labeling intensity seem prognostic of aggressive tumor behavior. Recent advancesin the development of a preclinical mouse model of NF1-associated OPG will permit investigation into improved detection strategies and chemotherapeutic and radiotherapy treatment protocols.

We describe a family with a history of cancer suggestive of the Li-Fraumeni syndrome (LFS). A 27-year-old woman suffered at 17 years of age from phyllodes breast tumor and was shown to carry a germline mutation in the TP53 gene. Two years after testing, she became pregnant and was offered prenatal diagnosis by her gynecologist. The patient expressed her commitment to deliver the baby regardless of its mutation status, but with a strong interest in having the child tested soon after the birth. When she was informed that testing of children is usually postponed until after they reach 18 years of age, she consulted several geneticists, who repeatedly discouraged her from the intent to test the newborn.In the end, the patient decided for prenatal genetic testing only to learn the mutation status of the child. This scenario being unacceptable, she was offered early postnatal testing of the child, and this analysis showed that the newborn boy carried the mutation. Based on this finding, the family was enrolled into a preventive screening program for childhood cancer. The case illustrates ethical problems associated with early predisposition testing in LFS, and the lack of consensus on this issue in the literature.

PURPOSE: MDM2 is a key negative regulator of p53 activity, and a single nucleotide polymorphism (SNP309, T>G change; rs 2279744) in its promoter increases the affinity for the transcription factor SP1, enhancing MDM2 expression. We carried out a pilot study to investigate the effect of this polymorphism on development and behavior of neuroblastoma, an extracranial pediatric tumor with unfrequent genetic inactivation of p53. EXPERIMENTAL DESIGN: We genotyped the MDM2-SNP309 alleles of tumor DNA from 239 neuroblastoma patients and peripheral blood DNA from 237 controls. In 40 of 239 neuroblastomas, the MDM2-SNP309 alleles were also genotyped in peripheral blood DNA. Data were analyzed by two-sided Fisher's exact test, log-rank test, and Kaplan-Meier statistics. Where appropriate, data are reported with 95% confidence intervals (CI). RESULTS: The frequency of both the T/G and G/G genotypes or the G/G or T/Ggenotype only was higher in neuroblastoma DNA samples than in controls: 60.3% (95% CI, 54.1-66.5) versus 47.3% (95% CI, 40.9-53.6), 30.4% (95% CI, 22.4-37.8) versus 15.0% (95% CI, 9.2-20.7), and 52.0% (95% CI, 45.0-59.9) versus 41.9% (95%CI, 35.3-48.5), respectively; Two-Sided Fisher's Exact Test P values were 0.006,0.003, and 0.048, respectively; Odds ratios were 1.69 (95% CI, 1.18-2.43), 2.45 (95% CI, 1.37-4.39) and 1.51 (95% CI, 1.02-2.22), respectively. A significant association (P = 0.016) between heterozygous (T/G)/homozygous (G/G) genotypes atSNP309 and advanced clinical stages was also shown. Homozygous/heterozygous SNP309 variant carriers had a shorter 5-year overall survival than patients withthe wild-type allele (P = 0.046; log-rank test). A shorter overall survival in patients with heterozygous/homozygous SNP309 was also observed in the subgroups with age at diagnosis >1 year and adrenal primary tumor (P = 0.024 and P = 0.014, respectively). CONCLUSIONS: Data from this pilot study suggest that the MDM2 G/Gand T/G-SNP309 alleles are markers of increased predisposition to tumor development and disease aggressiveness in neuroblastoma. However, additional studies with larger patient cohorts are required for a definitive assessment of the clinical relevance of these data.

BACKGROUND: T-lymphoblastic lymphoma (T-LBL) accounts for 25-30% of childhood non-Hodgkin's lymphoma and is closely related to T-lymphoblastic leukemia (T-ALL). Recently, we demonstrated distinct differences in gene expression between childhood T-LBL and T-ALL, but molecular pathogenesis and relevant protein expression patterns in T-LBL remain poorly understood. PROCEDURE: children with T-LBL with disseminated disease were registered and treated on COGprotocol 5971. Paraffin-embedded tumor tissue was obtained at diagnosis for immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) studies. We determined the pattern and intensity of staining for c-Myc, Skp2, Mib-1, p53,TCL-1, bcl-2, and bcl-6 proteins by IHC and c-Myc, p53, bcl-2, bcl-6, and TCR alpha/delta molecular alterations by FISH in 22 pediatric T-LBL cases. RESULTS: The majority of T-LBL samples expressed Mib-1 (59%) and c-Myc (77%) proteins in greater than 50% of the cells, but Skp2 (14%), p53 (14%), and bcl-2 (23%) expression was less common. FISH studies demonstrated 18% gains and 10% losses in c-Myc, 16% gains in p53, 12% gains and 6% losses in bcl-2, and 6% gains and 19% losses in bcl-6 with little direct correlation between the IHC and FISH studies.CONCLUSIONS: childhood T-LBL is a highly proliferative tumor associated with enhanced expression of c-Myc protein, but without detectable c-Myc molecular alterations. FISH studies did not identify consistent etiologies of molecular dysregulation, and future studies with other molecular approaches may be required to elucidate the molecular pathogenesis of childhood T-LBL.#CI- (c) 2008 Wiley-Liss, Inc.

Paediatric choroid plexus carcinomas (CPC) and adrenocortical carcinomas (ACC) are exceedingly rare tumours, each occurring at an annual rate of 0.3 cases per million children or less. Although both tumour types are associated with Li-Fraumeni syndrome (LFS), the penetrance of germline TP53 mutations in CPC remains to be established. We report here a young boy without a family history of cancer who presented with CPC and subsequently ACC. Genetic testing revealed a novel de novo germline TP53 mutation (E285V). Neither tumour underwent loss of heterozygosity. Consistent with this observation, functional analyses demonstrated that E285V acts as a dominant negative mutant that is defective in regulating target gene expression, growth suppression and apoptosis. These results further strengthen the association between germline TP53 mutations and childhood CPC, even when occurring in the absence of familial tumour susceptibility.

In 1990, an 18-month-old Micronesian girl was initially diagnosed with a right adrenocortical carcinoma. More than a decade later (2003), she was diagnosed with metastatic osteosarcoma with the primary in her right proximal fibula. Given this child's remarkable history of malignancy, she underwent testing for a genetic mutation that is associated with increased cancer formation. One such cancer syndrome is called Li-Fraumeni syndrome where approximately 70% of patients carry a genetic mutation in the p53 tumor suppressor gene. Patients with LFS are at risk for developing cancers of the breast, soft tissues, brain, bone, adrenal gland, and blood cells. mutational analysis of our patient did reveal the presence of a germline mutation of the p53 tumor suppressor gene. She was found to have a base pair change (A-->C) at nucleotide 394 resulting in a lysine to glutamine amino acid change at codon 132 (K132Q), which remarkably has never been described in association with either adrenocortical carcinoma or osteosarcoma.

OBJECTIVE: Choroid plexus carcinoma (CPC) has been associated with TP53 germlinemutations and Li-Fraumeni syndrome (LFS). We describe our finding of a novel germline mutation in the TP53 gene in a family with multiple malignancies and inassociation with a child presenting with CPC. METHOD: An 8-month-old male presented with seizure-like activity; imaging disclosed a 1.5-cm left ventricular mass confirmed to be CPC intra- and postoperatively. Family history was significant for a half-sister who died of a primary CNS sarcoma and a paternal grandmother negative for BRCA1, BRCA2, MLH1, and MSH2 mutations with multiple (>6) LFS spectrum malignancies. RESULTS: Familial TP53 testing revealed an A-->Tsubstitution at DNA position 13071, creating a deleterious Asn-->Ile substitution at amino acid 131 in exon 5. CONCLUSION: Physicians treating patients with CPC should be attuned to reviewing family history for risk factors suggestive of genetic cancer syndromes such as LFS. These syndromes markedly influence both the patient and family members and may alter postoperative treatment regimens.#CI- Copyright 2009 S. Karger AG, Basel.

Patients who survive retinoblastoma are at risk for developing additional malignant neoplasms, including tumors of the sinonasal tract. We report 2 cases of secondary sinonasal malignancy arising in pediatric patients previously treated for retinoblastoma, with features of neuroendocrine carcinoma. Both lesions were characterized by a proliferation of round to oval cells arranged insolid sheets, trabeculae, and nests, diffusely infiltrating nasal mucosa and bone tissue. Immunohistochemically, they were diffusely positive for epithelial markers, as well as for neuroendocrine markers and for TP53 and retinoblastoma gene products. TP53 gene analysis showed the presence of a missense mutation P72R (CCC/CGC) and a single nucleotide polymorphism P36P (CCG/CCA) in exon 4 in 1 case. Literature review revealed 5 previously reported cases, ALL showing primitive undifferentiated morphology with variable expression of neural and epithelial markers. These tumors represent a peculiar subset of undifferentiatedsinonasal neoplasms with extremely aggressive clinical behavior.

Patients who survive retinoblastoma are at risk for developing additional malignant neoplasms, including tumors of the sinonasal tract. We report 2 cases of secondary sinonasal malignancy arising in pediatric patients previously treated for retinoblastoma, with features of neuroendocrine carcinoma. Both lesions were characterized by a proliferation of round to oval cells arranged insolid sheets, trabeculae, and nests, diffusely infiltrating nasal mucosa and bone tissue. Immunohistochemically, they were diffusely positive for epithelial markers, as well as for neuroendocrine markers and for TP53 and retinoblastoma gene products. TP53 gene analysis showed the presence of a missense mutation P72R (CCC/CGC) and a single nucleotide polymorphism P36P (CCG/CCA) in exon 4 in 1 case. Literature review revealed 5 previously reported cases, ALL showing primitive undifferentiated morphology with variable expression of neural and epithelial markers. These tumors represent a peculiar subset of undifferentiatedsinonasal neoplasms with extremely aggressive clinical behavior.

PURPOSE: A clinical testing cohort was used to gain a broader understanding of the spectrum of tumors associated with germline p53 mutations to aid clinicians in identifying high-risk families. PATIENTS AND METHODS: Full sequencing of the coding exons (2 to 11) and associated splice junctions of the p53 gene was performed on 525 consecutive patients whose blood samples were submitted for diagnostic testing. Clinical features of p53 germline carriers in this cohort were characterized, clinical referral schemes based on reported p53-associated family phenotypes were evaluated, and practical mutation prevalence tables were generated. RESULTS: mutations were identified in 91 (17%) of 525 patients submitted for testing. ALL families with a p53 mutation had at least one family member with a sarcoma, breast, brain, or adrenocortical carcinoma (ACC). Every individual with a choroid plexus tumor (eight of eight) and 14 of 21 individualswith a childhood ACC had a mutation regardless of family history. Based on reported personal and family history, 95% of patients (71 of 75) with a mutationmet either classic Li Fraumeni syndrome (LFS) or Chompret criteria. A simplifiedprevalence table provides a concise summary of individual and family characteristics associated with p53 mutations. CONCLUSION: This is, to our knowledge, the largest single report of diagnostic testing for germline p53 mutations, yielding practical mutation prevalence tables and suggesting clinicalutility of classic LFS and Chompret criteria for identifying a subset of cancer-prone families with p53 germline mutations, with important implications for diagnosis and management.

The highly aggressive muscle cancer alveolar rhabdomyosarcoma (ARMS) is one of the most common soft tissue sarcoma of childhood, yet the outcome for the unresectable and metastatic disease is dismal and unchanged for nearly three decades. To better understand the pathogenesis of this disease and to facilitatenovel preclinical approaches, we previously developed a conditional mouse model of ARMS by faithfully recapitulating the genetic mutations observed in the humandisease, i.e., activation of Pax3:Fkhr fusion gene with either p53 or Cdkn2a inactivation. In this report, we show that this model recapitulates the immunohistochemical profile and the rapid progression of the human disease. We show that Pax3:Fkhr expression increases during late preneoplasia but tumor cells undergoing metastasis are under apparent selection for Pax3:Fkhr expression. At a whole-genome level, a cross-species gene set enrichment analysis and metagene projection study showed that our mouse model is most similar to human ARMS when compared with other pediatric cancers. We have defined an expression profile conserved between mouse and human ARMS, as well as a Pax3:Fkhr signature, including the target gene, SKP2. We further identified 7 "druggable" kinases overexpressed across species. The data affirm the accuracy of this genetically engineered mouse model.

mutations in the gene TP53, which codifies the tumor suppressor protein p53, arefound in about 50% of tumors. These mutations can occur not only at somatic level, but also in germline. pediatric cancer patients, mostly with additional family history of malignancy, should be considered as potential TP53 germline mutation carriers. Germline TP53 mutations and polymorphisms have been widely studied to determine their relation with different tumors' pathogenesis. Our aimwas to analyze the occurrence frequency of germline TP53 mutations and polymorphisms and to relate these to tumor development in a pediatric series. Peripheral blood mononuclear cell samples from 26 children with solid tumors [PST] and 21 pediatric healthy donors [HD] were analyzed for germline mutations and polymorphisms in TP53 gene spanning from exon 5 to 8 including introns 5 and7. These PCR amplified fragments were sequenced to determine variations. A heterozygous mutation at codon 245 was found in 1/26 PST and 0/21 HD. Comparative polymorphisms distribution, at position 14181 and 14201(intron 7), between HD and PST revealed a trend of association (p= 0.07) with cancer risk. HD group disclosed a similar polymorphism distribution as published data for Caucasian and Central/South American populations. This is the first study about TP53 variant frequency and distribution in healthy individuals and cancer patients in Argentina.

Embryonal tumors are a group of malignant neoplasms that most commonly affect the pediatric population. Embryonal tumor with abundant neuropil and true rosettes is a recently recognized rare tumor. It is composed of neurocytes and undifferentiated neuroepithelial cells arranged in clusters, cords and several types of rosettes in a prominent neuropil-rich background. We describe a new case of this tumor. The patient, a 24-month-old female infant, was referred to the Meyer children's Hospital with a history of right brachio-crural deficit associated with occasional episodes of headache and vomiting. Computed tomography scan and MRI revealed a large bihemispheric mass. The patient underwent two consecutive surgeries. The resultant surgical resection of the tumor was macroscopically complete. The postoperative period was uneventful. On light microscopy the tumor showed a composite morphology: embryonal tumor with abundant neuropil and true rosettes (specimen from the first surgery); medulloepitheliomawith mesenchymal and epithelial areas (specimen from the second surgery). The immunohistochemistry evidenced the heterogeneous (neuronal, mesenchymal and epithelial) immunoprofile of tumoral cells. By real-time polymerase chain reaction (RT-PCR), the PTEN gene expression in the tumor was lower than in the five non-neoplastic brain tissues used as control. mutation analysis did not show any variation in INI-1 and PTEN sequence while P53 analysis showed the presence of homozygote P72R variation. Fluorescent in situ hybridization analysis showed polysomy of chromosome 2 while amplification of N-MYC was not detected. Owing tothe rarity of embryonal tumor with abundant neuropil and true rosettes, each newcase should be recorded to produce a better clinical, pathological and molecularcharacterization of this lesion.

Neuroblastoma is derived from neural crest precursor components of the peripheral sympathetic nervous system and accounts for more than 15% of ALL pediatric cancer deaths. A clearer understanding of the molecular basis of neuroblastoma is required for novel therapeutic approaches to improve morbidity and mortality. Neuroblastoma is uniformly p53 wild type at diagnosis and must overcome p53-mediated tumor suppression during pathogenesis. Amplification of the MYCN oncogene correlates with the most clinically aggressive form of the cancer, and MDM2, a primary inhibitor of the p53 tumor suppressor, is a direct transcriptional target of, and positively regulated by, both MYCN and MYCC. We hypothesize that MDM2 contributes to MYCN-driven tumorigenesis helping to ameliorate p53-dependent apoptotic oncogenic stress during tumor initiation and progression. To study the interaction of MYCN and MDM2, we generated an Mdm2 haploinsufficient transgenic animal model of neuroblastoma. In Mdm2(+/-)MYCN transgenics, tumor latency and animal survival are remarkably extended, whereas tumor incidence and growth are reduced. Analysis of the Mdm2/p53 pathway revealsremarkable p53 stabilization counter-balanced by epigenetic silencing of the p19(Arf) gene in the Mdm2 haploinsufficient tumors. In human neuroblastoma xenograft models, conditional small interfering RNA-mediated knockdown of MDM2 in cells expressing wild-type p53 dramatically suppresses tumor growth in a p53-dependent manner. In summary, we provided evidence for a crucial role for direct inhibition of p53 by MDM2 and suppression of the p19(ARF)/p53 axis in neuroblastoma tumorigenesis, supporting the development of therapies targeting these pathways.

OBJECTIVE: To detect the germline TP53 gene mutation in a child with pediatric adrenocortical carcinoma (ADCC) in order to provide genetic diagnosis and counseling. METHODS: Genomic DNA was extracted from peripheral blood from a girlwith ADCC and her parents. ALL TP53 exons and their flanking intronic sequences were PCR-amplified and subjected to automatic DNA sequencing. RESULTS: Direct sequencing of PCR products revealed a heterozygous G insertion between nucleotide 522 and 523 (c.522-523insG) in TP53 exon 5. This novel mutation is predicted to result in a frame shift at codon 175, producing a new reading frame ending in a stop at position 6 (p.R175AfsX6). The same heterozygous mutation was also found in her father, but not in her mother. CONCLUSION: A novel germline mutation in the TP53 gene has been identified in one case with pediatric ADCC.

Virilizing adrenocortical carcinoma and Turner syndrome have opposite clinical manifestations in some aspects. Here, we report on the first case of virilizing adrenocortical carcinoma in a girl with Turner syndrome. A 2 10/12-year-old girlpresented pubic hair of Tanner stage III with clitomegaly, deepening of her voice, and tall stature. No other morphologic anomaly was found. Biochemical assessment revealed normal electrolytes with pronounced elevation of adrenal androgens. She was found to have a large mass of the left adrenal gland on abdominal computed tomography scan. She underwent complete resection of the mass, and pathology was consistent with adrenocortical carcinoma. She was tested for TP53 gene mutation, and we found a de novo TP53 gene mutation (Val143Ala) as well as a 45,X karyotype.

Genomic and immunologic surveillance mechanisms are crucial in protection from cancer. The tumor suppressor protein p53, encoded by TP53, is a major regulator of genome surveillance. Among the natural sequence variants of TP53, rs1042522 (R72P) modifies the risk for solid tumors. To investigate its relevance in childhood acute lymphoblastic leukemia (ALL) susceptibility, we genotyped 114 cases and 414 newborn controls from Wales (UK) for polymorphisms in TP53 (R72P),its negative regulator MDM2 (single-nucleotide polymorphism SNP309, rs2279744), and selected HLA complex genes whose products interact with TP53. TP53 R72P showed a risk association with gene dosage effect (P=0.002) resulting in a strong association of homozygous genotype (OR=2.9, 95% CI=1.5-5.6) and no sex effect. SNP309 did not show any association with primary susceptibility to childhood ALL, even after stratification by sex. However, females with SNP309 minor allele had earlier onset of childhood ALL (median age at diagnosis was 36 months in females, but 60 months in males; P=0.002). The HLA complex genes did not show any statistically significant interaction with R72P. We have therefore identified TP53 R72P as a possible risk modifier for childhood ALL and the association of MDM2 with age at onset with sex effect suggests prenatal hormonal programming ofchildhood ALL susceptibility.

Medulloblastomas are highly malignant, poorly differentiated childhood tumours arising in the cerebellum. These tumors rarely lose TP53, which is the most commonly mutated gene in cancer. Recent work has shown that the basal level of p53 plays an important role in maternal reproduction by maintaining the expression of LIF in the uterus. Since LIF can maintain the undifferentiated state of stem cells we set out to ask if p53 regulates LIF in the human medulloblastoma cell lines DAOY and D283MED. We also used p53-/- and p53+/+ isogenic HCT116 colorectal carcinoma cell lines, already reported to exhibit p53-dependent expression of the LIF D transcript, to establish the extent of p53-dependency for LIF M and T alternative transcripts. Whilst ALL three known, full-length alternative transcripts are more abundant in p53+/+ cells, the alternative LIF M and T transcripts appear particularly sensitive to p53. In thep53 wild-type medulloblastoma cell line D283MED chromatin immunoprecipitation experiments showed p53 binding to the LIF gene. The mutant p53 expressed in lineDAOY did not bind to this region or to the p21(WAF1) p53 binding site. RNA interference against either WIP1 or SIRT1 stabilized p53 and enhanced the transcription of LIF in D283MED cells. Interestingly, siRNA against WIP1 or SIRT1 also induced increased apoptosis in the medulloblastoma line D283MED and, over alonger time period, in DAOY cells. We speculate that suppression of p53 functionby combined WIP1-mediated dephosphorylation and SIRT1 deacetylation enables medulloblastoma cell survival but p53-dependent and independent apoptotic pathways remain intact. Thus small molecule inhibitors of SIRT1 may be useful intreatment of medulloblastoma.

High levels of expression of the p53 protein and gene mutations have been described in adult hepatocellular carcinomas. It has been postulated that specific mutations in exon 7 may be caused by aflatoxin exposure. To determine whether p53 mutations occur in childhood liver cancer unassociated with aflatoxin exposure or hepatitis B virus (HBV) infection, we have analyzed three histologically distinct tumor types. Two techniques were used to access p53 in the tumors: (1) expression studies of the p53 protein were performed using the polyclonal antibody CM1 and immunohistochemistry, and (2) DNA sequencing was performed. p53 Protein was detectable by immunohistochemistry in 10 of 15 hepatoblastomas, six of nine hepatocellular carcinomas, and one of one embryonalsarcomas. Solid phase single-stranded DNA sequencing across exons 5 through 9 showed normal sequence in ALL cases. These results indicate that p53 is overexpressed in a majority of childhood liver cancers, but this abnormal p53 expression does not seem to be caused by mutations in the p53 gene.

AIM: Determination of frequency and prognostic significance of murine double minute protein-2 (MDM-2) over expression and its association with p53 status in children with acute lymphoblastic leukemia (ALL). METHODS: MDM-2 expression by flow cytometry and p53 gene status by PCR were determined in peripheral blood orbone marrow of 46 ALL children (at initial diagnosis) and control group. RESULTS: MDM-2 was significantly overexpressed in 15 patients (32.6%). p53 mutation was detected in six out of 46 patients at initial diagnosis, three of them were out of 29 cases achieving complete remission (CR) and the other three cases were outof 17 of relapsed patients, which is significantly higher than CR group (P<0.05). Positive correlation was found between the MDM-2 overexpression and initial WBCscount, peripheral blast cell count and presence of CNS blasts (P<0.05, <0.05 and<0.05 respectively). CONCLUSION: MDM-2 is overexpressed in a significant number of childhood ALL, and more often observed in the poor outcome group and its frequency is not related to p53 status. Measurement of MDM-2 as a bad prognosticmarker even in cases with non-mutant p53 is very important. Moreover, MDM-2 may be a potential molecular target for production of new cancer therapy.

BACKGROUND & AIMS: Infantile and childhood liver tumors have been found in 0.42%of individuals with a germline mutation in the adenomatous polyposis coli (APC) gene. This study analyzed a hepatocellular adenoma of a 2-year-old child at riskfor familial adenomatous polyposis to identify genetic alterations in hepatic tumors initiated by APC germline mutations. METHODS: mutation screening was performed for the APC gene (protein truncation test and DNA sequence analysis), p53 gene (complementary DNA cloning and sequencing), and members of the Ras genefamily (complementary DNA sequence analysis). RESULTS: Both the mother and childhad a germinal CGA-->TGA transition at codon 1451 leading to an Arg1451Ter stop mutation in the APC gene. Loss of the wild-type APC allele as a second hit revealed hemizygosity of the inherited mutation in the tumor. Furthermore, a CGC-->CAC transition in the p53 gene of the adenoma resulted in an Arg-->His missense mutation in codon 175. No loss of heterozygosity was detected at the p53 locus. Ras gene mutations were not found. CONCLUSIONS: Biallelic inactivation ofAPC gene and p53 mutation are early events in hepatocellular tumorigenesis. Additional reports will confirm whether inherited APC gene mutations between codon 1444 and 1578 increase the risk for hepatic tumors.

Myc proteins (c-myc, Mycn and Mycl) target proliferative and apoptotic pathways vital for progression in cancer. Amplification of the MYCN gene has emerged as one of the clearest indicators of aggressive and chemotherapy-refractory diseasein children with neuroblastoma, the most common extracranial solid tumor of childhood. Phosphorylation and ubiquitin-mediated modulation of Myc protein influence stability and represent potential targets for therapeutic intervention. Phosphorylation of Myc proteins is controlled in-part by the receptor tyrosine kinase/phosphatidylinositol 3-kinase/Akt/mTOR signaling, with additional contributions from Aurora A kinase. Myc proteins regulate apoptosis in part through interactions with the p53/Mdm2/Arf signaling pathway. mutation in p53 iscommonly observed in patients with relapsed neuroblastoma, contributing to both biology and therapeutic resistance. This review examines Myc function and regulation in neuroblastoma, and discusses emerging therapies that target Mycn.

BTI - GeneReviews#. Li-Fraumeni syndrome (LFS) is a cancer predisposition syndrome associated with the development of the following classic tumors: soft tissue sarcoma, osteosarcoma, pre-menopausal breast cancer, brain tumors, adrenocortical carcinoma (ACC), and leukemias. In addition, a variety of other neoplasms may occur. LFS-related cancers often occur in childhood or young adulthood and survivors have an increased risk for multiple primary cancers. Age-specific cancer risks have been calculated. LFS is diagnosed in individuals meeting established clinical criteria or in those who have a germline mutation in TP53 regardless of family cancer history. At least 70% of individuals diagnosed clinically have an identifiable germline mutation in TP53, the only gene so far identified in which mutations are definitively associated with LFS. Treatment ofmanifestations: Routine oncologic management is recommended for malignancies in individuals with LFS, with the exception of breast cancer, in which mastectomy rather than lumpectomy is recommended in order to reduce the risks of a second primary breast tumor and avoid radiation therapy. Concerns about increased risk for radiation-induced second primary tumors has led to more cautious use of therapeutic radiation in general, but most experts recommend that treatment efficacy be prioritized above concerns about late effects after careful analysisof risks and benefits. Prevention of primary manifestations: Prophylactic mastectomy to reduce the risk for breast cancer is an option for women with a germline TP53 mutation. Recent recommendations for colonoscopy may be consideredsurveillance as well as primary prevention of colorectal cancer. Prevention of secondary complications: Avoidance of exposure to radiation therapy, when possible, to reduce the risk of secondary radiation-induced malignancies. Surveillance: There are no definitive prospective data on the optimal methods for and efficacy of tumor surveillance for children or adults with a germline TP53 mutation. Currently, it is recommended that: (1) children and adults undergo comprehensive annual physical examination; (2) children and adults be encouragedsee a physician promptly for evaluation of lingering symptoms and illnesses; (3)women undergo breast cancer monitoring, with annual breast MRI and twice annual clinical breast examination beginning at age 20-25 years. The use of mammograms has been controversial because of radiation exposure and limited sensitivity. When included, annual mammograms should alternate with breast MRI, with one modality every six months; (4) adults consider routine screening for colorectal cancer with colonoscopy every 2-3 years beginning no later than age 25 years; (5) individuals consider organ-targeted surveillance based on the pattern of cancer observed in their family. Intensified surveillance with whole-body MRI protocolsfor adults and children who carry a germline TP53 mutation are being evaluated in investigational settings. Agents/circumstances to avoid: People with germline TP53 mutations should: (1) avoid known carcinogens including sun exposure, tobacco use, occupational exposures, and excessive alcohol use; and (2) minimizeexposure to diagnostic and therapeutic radiation. Evaluation of relatives at risk: It is appropriate to offer genetic counseling and testing to ALL relativeswho are at risk of having a familial TP53 mutation. LFS is inherited in an autosomal dominant manner. The proportion of individuals with a de novo germlineTP53 mutation is estimated to be between 7% and 20%. Offspring of an affected individual have a 50% chance of inheriting the deleterious mutation. Predisposition testing for at-risk family members and prenatal testing for pregnancies at increased risk are possible if the heritable mutation in the family has been identified.#CI- Copyright (c) 1993-2013, University of Washington, Seattle. ALL rights reserved.#FED - Pagon, Roberta A#ED- Pagon RA#FED - Adam, Margaret P#ED- Adam MP#FED - Bird, Thomas D#ED- Bird TD#FED - Dolan, Cynthia R#ED- Dolan CR#FED - Fong, Chin-To#ED- Fong CT#FED - Stephens, Karen#ED- Stephens K#FAU - Schneider, Katherine

The murine double minute protein-2 (MDM-2) oncogene is a determinant of embryogenesis, tumorigenesis, and cell cycle progression. The effects of MDM-2 on these processes depend, in part, on its ability to inactivate the p53 tumor suppressor gene. Our goal was to determine whether MDM-2 protein overexpressionsor p53 gene mutations are a frequent event in poor outcome pediatric acute lymphoblastic leukemia (ALL). This work was conducted on 46 children with ALL (31 males and 15 females) with age range 2-18 years, 18 children with matched age and sex were enrolled in the study as a control group. The MDM-2 expression by flowcytometry and p53 gene status by PCR were determined in peripheral blood or bone marrow of ALL children (at initial diagnosis) and also of control group. The ALL children were treated by the modified BFM 76179 protocol of therapy, 29 patients (63%) achieved complete remission, while 17 patients (37%) were subsequently failed to achieve complete remission or relapsed within 6 months ofachieving complete remission (CR). MDM-2 was significantly overexpressed in 15 ALL patients (32.6%), compared to that of healthy controls, 4 of them (4/15), were out of 29 cases of CR (13.8%), and the other 11 cases were out of 17 relapsed cases (64.7%). In contrast to overexpression of MDM-2, the mutation of p53 was detected in 6 (13%) out of 46 ALL patients at the initial time of diagnosis, 3 of them (10.3%) were out of 29 cases of CR and the other 3 cases (17.6%) were out of 17 of relapsed group, which is significantly higher than CR group (P < 0.05). In relapsed group, 2 patients out of 3 cases with p53 mutationwere MDM-2 negative, also, ALL 3 cases of mutant P53 among patients in CR were negative MDM2. A positive correlation was found between the MDM-2 overexpressionand initial WBCs count, blast cell counts in peripheral blood and presence of CNS blasts (p < 0.05, p < 0.05 and p < 0.05 respectively). These results indicate that MDM-2 is overexpressed in a significant number of childhood ALL, it is morefrequent in relapsed cases and its frequency is not related to p53 status. Thus measuring of MDM-2 as a bad prognostic marker even in cases with non mutant P53 is very important. Moreover, MDM-2 may be a potential molecular target for production of new cancer therapy.

PURPOSE: Wilms' tumor (WT), the most common pediatric renal malignancy, is associated with mutations in several well-characterized genes, most notably WT1,CTNNB1, WTX, and TP53. However, the majority of cases do not harbor mutations inthese genes. We hypothesized that additional drivers of tumor behavior would be contained within areas of consistent genomic copy number change, especially those associated with the WT risk groups defined by the International Society of Paediatric Oncology (SIOP). EXPERIMENTAL DESIGN: We analyzed high-resolution (Affymetrix 250K single nucleotide polymorphism array) genomic copy number profiles of over 100 tumors from selected risk groups treated under the SIOP protocols, further characterizing genes of interest by sequencing, Multiplex Ligation-dependent Probe Amplification, or fluorescence in situ hybridization. RESULTS: We identified FBXW7, an E3 ubiquitin ligase component, as a novel Wilms' tumor gene, mutated or deleted in approximately 4% of tumors examined. Strikingly, 3 of 14 (21%) of tumors with epithelial type histology after neoadjuvant chemotherapy had FBXW7 aberrations, whereas a fourth WT patient had germline mutations in both FBXW7 and WT1. We also showed that MYCN copy number gain, detected in 9 of 104 (8.7%) of cases, is relatively common in WT and significantly more so in tumors of the high risk diffuse anaplastic subtype (6 of 19, 32%). CONCLUSIONS: Because MYCN is itself a target of FBXW7-mediated ubiquitination and degradation, these results suggest that a common pathway is dysregulated by different mechanisms in various WT subtypes. Emerging therapies that target MYCN, which is amplified in several other pediatric cancers, may therefore be of value in high risk Wilms' tumor.#CI- Copyright 2010 AACR.

Rhabdoid meningioma is an uncommon meningioma variant categorized as WHO grade III. The majority of cases occur in adulthood. Herein, we describe a right fronto-temporal rhabdoid meningioma affecting a 3-year-old boy. The lesion measured approximately 4 cm in diameter and incorporated the ipsilateral middle cerebral artery. Sub-total surgical excision of the mass was performed. Histologically, the tumor was mainly composed of globoid plump cells with inclusion-like eosinophilic cytoplasm, peripheral nuclei, prominent nucleoli andoccasional intra-nuclear cytoplasmic pseudo-inclusion. The cells appeared in many areas loosely arranged and focally disclosed a papillary architecture. At immunohistochemistry, the tumor cells were EMA, vimentin, HHF35, PgR, INI-1 and p53 positive. The proliferative index (Mib-1) was 15% in the most positive areas. Ultrastructurally, tumoral cells showed an abundant cytoplasm, which was filled with numerous intermediate filaments. Desmosomal junctions were seen. RT-PCR revealed the presence of NF2 gene expression. Molecular study did not indicate alterations of the INI-1 gene, whereas it showed the presence of Pro72Arg in exon 4 at heterozygous state in the TP53 gene. Morphologic features along with immunohistochemical, ultrastructural and molecular results were consistent with the diagnosis of rhabdoid meningioma. The patient was treated with chemotherapy.The lesion remained stable after 33 months of follow-up. Rhabdoid meningiomas rarely occur in children. Owing to its rarity, each new case should be recorded to produce a better clinical, pathological, molecular, prognostic and therapeutic characterization of this lesion.#CI- (c) 2010 Japanese Society of Neuropathology.

Li-Fraumeni syndrome (LFS) is one of the familial cancers characterized by different tumors and hereditary TP53 mutations. The adrenocortical carcinoma (ACC) association with acute leukemia is unusual in childhood, even in LFS. The authors here present a family with pR337P mutation in TP53 gene who had a child with acute lymphoblastic leukemia (ALL) and associated adrenocortical carcinoma as a case 1 and his cousin with brain tumor as a case 2. A hereditary TP53 mutation supported the diagnosis of LFS in this family. The patients had many difficulties in treatment strategies and succumbed to death. The availability ofa reliable molecular marker to detect the R337P TP53 mutation allows the rapid identification of carriers in families that have a child with ACC. Once identified, carriers could be screened for early detection of ACC by imaging andendocrine studies and should be given psychological support to prevent anxiety for death. Whether early detection of ACC will reduce the mortality in these patients remains to be determined.

BACKGROUND: Human osteosarcoma is the most common pediatric bone tumor. There islimited understanding of the molecular mechanisms underlying osteosarcoma oncogenesis, and a lack of good diagnostic as well as prognostic clinical markers for this disease. Recent discoveries have highlighted a potential role of a number of genes including: RECQL4, DOCK5, SPP1, RUNX2, RB1, CDKN1A, P53, IBSP, LSAMP, MYC, TNFRSF1B, BMP2, HISTH2BE, FOS, CCNB1, and CDC5L. METHODS: Our objective was to assess relative expression levels of these 16 genes as potential biomarkers of osteosarcoma oncogenesis and chemotherapy response in human tumors. We performed quantitative expression analysis in a panel of 22 human osteosarcoma tumors with differential response to chemotherapy, and 5 normal human osteoblasts. RESULTS: RECQL4, SPP1, RUNX2, and IBSP were significantly overexpressed, and DOCK5, CDKN1A, RB1, P53, and LSAMP showed significant loss ofexpression relative to normal osteoblasts. In addition to being overexpressed inosteosarcoma tumor samples relative to normal osteoblasts, RUNX2 was the only gene of the 16 to show significant overexpression in tumors that had a poor response to chemotherapy relative to good responders. CONCLUSION: These data underscore the loss of tumor suppressive pathways and activation of specific oncogenic mechanisms associated with osteosarcoma oncogenesis, while drawing attention to the role of RUNX2 expression as a potential biomarker of chemotherapy failure in osteosarcoma.

Glioblastoma multiforme (GBM) is one of the deadliest tumors afflicting humans, and the mechanisms of its onset and progression remain largely undefined. Our attempts to elucidate its molecular pathogenesis through DNA copy-number analysis by genome-wide digital karyotyping and single nucleotide polymorphism arrays identified a dramatic focal amplification on chromosome 1q32 in 4 of 57 GBM tumors. Quantitative real-time PCR measurements revealed that HDMX is the most commonly amplified and overexpressed gene in the 1q32 locus. Further genetic screening of 284 low- and high-grade gliomas revealed that HDMX amplifications occur solely in pediatric and adult GBMs and that they are mutually exclusive ofTP53 mutations and MDM2 amplifications. Here, we demonstrate that HDMX regulatesp53 to promote GBM growth and attenuates tumor response to chemotherapy. In GBM cells, HDMX overexpression inhibits p53-mediated transcriptional activation of p21, releases cells from G0 to G1 phase, and enhances cellular proliferation. HDMX overexpression does not affect the expression of PUMA and BAX proapoptotic genes. While in GBM cells treated with the chemotherapeutic agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), HDMX appears to stabilize p53 and promote phosphorylation of the DNA double-stranded break repair protein H2AX, up-regulate the DNA repair gene VPX, stimulate DNA repair, and confer resistanceto BCNU. In summary, HDMX exhibits bona fide oncogenic properties and offers a promising molecular target for GBM therapeutic intervention.

Clear cell sarcoma (CCSK) of the kidney is an uncommon but distinctive pediatricrenal tumor with a characteristic histological pattern and marked propensity forbone metastasis. The rare anaplastic variant constitutes about 3% of cases of CCSK and carries an unfavorable prognosis, with increased tumor recurrence and resistant to chemotherapy. This variant show high frequency of p53 gene mutationand p53 over expression in comparison to the usual CCSK. We present a case of anaplastic variant of CCSK in an 10-year-old boy with both cytologic and histologic features, highlighting the importance of recognizing this rare entity.

Neuroblastoma is a childhood malignancy of the sympathetic nervous system. The tumor exhibits two different phenotypes: favorable and unfavorable. MYCN amplification is associated with rapid tumor progression and the worst neuroblastoma disease outcome. We have previously reported that inhibitors of histone deacetylase (HDAC) and proteasome enhance favorable neuroblastoma gene expression in neuroblastoma cell lines and inhibit growth of these cells. In this study, we investigated the effect of trichostatin A or TSA (an HDAC inhibitor), and epoxomycin (a proteasome inhibitor) on MYCN and p53 expression in MYCN-amplified neuroblastoma cells. It was found that TSA down-regulated MYCN expression, but Epoxomycin and the TSA/Epoxomycin combination led to MYCN hyper-expression in MYCN-amplified neuroblastoma cell lines. Despite their contrasting effects on MYCN expression, TSA and Epoxomycin caused growth suppression and cell death of the MYCN-amplified cell lines examined. Consistentwith these data, forced hyper-expression of MYCN in MYCN-amplified IMR5 cells via transfection resulted in growth suppression and the increased expression of several genes known to suppress growth or induce cell death. Furthermore, Epoxomycin as a single agent and its combination with TSA enhance p53 expressionin the MYCN-amplified neuroblastoma cell lines. Unexpectedly, co-transfection ofTP53 and MYCN in IMR5 cells resulted in high p53 expression but a reduction of MYCN expression. Together our data suggest that either down regulation or hyper-expression of MYCN results in growth inhibition and/or apoptosis of MYCN-amplified neuroblastoma cells. In addition, elevated p53 expression has a suppressive effect on MYCN expression in these cells.

childhood adrenocortical tumor (ACT), a very rare malignancy, has an annual worldwide incidence of about 0.3 per million children younger than 15 years. Theassociation between inherited germline mutations of the TP53 gene and an increased predisposition to ACT was described in the context of the Li-Fraumeni syndrome. In fact, about two-thirds of children with ACT have a TP53 mutation. However, less than 10% of pediatric ACT cases occur in Li-Fraumeni syndrome, suggesting that inherited low-penetrance TP53 mutations play an important role in pediatric adrenal cortex tumorigenesis. We identified a novel inherited germlineTP53 mutation affecting the acceptor splice site at intron 10 in a child with anACT and no family history of cancer. The lack of family history of cancer and previous information about the carcinogenic potential of the mutation led us to further characterize it. Bioinformatics analysis showed that the non-natural andhighly hydrophobic C-terminal segment of the frame-shifted mutant p53 protein may disrupt its tumor suppressor function by causing misfolding and aggregation. Ourfindings highlight the clinical and genetic counseling dilemmas that arise when an inherited TP53 mutation is found in a child with ACT without relatives with Li-Fraumeni-component tumors.

BACKGROUND: The inherited, low-penetrance arginine-to-histidine substitution at codon 337 (R337H) of the tumor protein 53 gene (TP53) is clustered in southeast Brazil (estimated frequency, 0.3%). Although its tumorigenic effect initially appeared to be tissue-specific, recent evidence suggests its association with a broader range of tumors. Therefore, the authors of this report investigated the spectrum of pediatric malignancies associated with the TP53 R337H mutation at a single referral institution in southeast Brazil. METHODS: Genomic DNA samples from 493 children with malignancies were screened for the R337H mutation. Available tumor samples from carriers were investigated for loss of heterozygosity (LOH) and nuclear p53 accumulation. Clinical data were obtained from medical records. RESULTS: Sixty-five of 70 patients (93%) with adrenocortical tumors (ACTs), 9 of 13 patients (69%) with choroid plexus carcinoma (CPC), and 3 of 41 patients (7.3%) with osteosarcoma carried the mutation. The proportion of CPC to choroid plexus papilloma (CPP) was much higher than that reported elsewhere. Osteosarcoma in carriers had a significantly poorer outcome (P = .02). The mutation was not identified in patients who had acute lymphoblastic leukemia (ALL) (n = 187), recurrent ALL (n = 49), acute myeloid leukemia (n = 44), lymphoma (n = 30), non-CPC central nervous system tumors (n =26), Ewing sarcoma (n = 25), or rhabdomyosarcoma (n = 8). Among the tumors that were available for analysis, LOH with retention of the mutant allele was confirmed in 21 of 21 ACTs, in 2 of 2 CPCs, and in 2 of 3 osteosarcomas that were positive for R337H. CPCs and osteosarcomas that were positive for R337H had marked nuclear accumulation of p53. CONCLUSIONS: The current findings demonstrated compellingly that the TP53 R337H mutation is associated not only with ACT but also with CPC and, to a lesser extent, with osteosarcoma, both of which are core-component tumors of the Li-Fraumeni syndrome.#CI- 2010 American cancer Society.

Li-Fraumeni syndrome (LFS) is an inherited cancer syndrome that affects a small percentage of the population worldwide. LFS is characterized by multiple cancersin affected family members and is devastating to ALL diagnosed patients and their relatives. A link has been identified between LFS and mutations in the tumor-suppressor gene that encodes for the P53 protein, and much research has been done on the effect of this mutation in tumorigenesis. However, the natural history of the disease has no definitive pathway, and additional research is under way. LFS is rare, can present in many ways, requires complex management, and has tumors that often first present in childhood. Therefore, pediatric nursepractitioners should be aware of LFS as a potential differential diagnosis in patients with multiple tumors, certain rare tumors, or most importantly, a family history notable for multiple early-onset cancers.

Advances in understanding the molecular basis of primitive neuroectodermal tumors of the central nervous system (CNS-PNET) biology are critical to improve patientoutcome. Recently, new data on their molecular features have been reported, suggesting that supratentorial PNET (s-PNET) in adult patients may represent a specific tumor entity among CNS-PNETs. In this study, we analyzed the clinicopathologic and molecular features of 12 cases of s-PNET in adult patients. The follow-up analysis showed that these tumors have an aggressive clinical behavior. At the histopathologic level, they resembled their pediatric counterpart, showing a variable spectrum of neuronal differentiation. These cases did not show astrocytic differentiation; therefore, they did not qualify for thedifferential diagnosis of glioblastoma variants. The tumors were also screened for mutation of TP53, IDH1, IDH2, and beta-catenin, using single strand conformation polymorphism-based and sequencing assays, and were analyzed for c-myc/N-myc gene copy numbers with a quantitative polymerase chain reaction-based method. The strand conformation polymorphism-based mutational analysis showed that 5 tumors harbored TP53 mutations. In 2 cases, a mutation at codon 132 of the IDH1 gene was also found. No mutations of the beta-catenin or IDH2 genes were identified. No cases presented c-myc or N-myc amplifications. Only 1 case presented overexpression of epidermal growth factor receptor. In conclusion, ourdata show a high incidence of TP53 mutations in this group of tumors and show, in comparison with pediatric s-PNET, the absence of amplification of the c-myc/N-myc genes, indicating that s-PNET in adult patients may represent a specific subset of tumors among CNS-PNETs.

pediatric rhabdomyosarcoma occurs as two biologically distinct histological variants, embryonal (ERMS) and alveolar (ARMS). To identify genomic changes thatdrive ERMS pathogenesis, we used a new array comparative genomic hybridization (aCGH) platform to examine a specific subset of ERMS tumors, those occurring in children with clinically defined intermediate-risk disease. The aCGH platform used has an average probe spacing approximately 1 kb, and can identify genomic changes with single gene resolution. Our data suggest that these tumors share a common genomic program that includes inactivation of a master regulator of the p53 and Rb pathways, CDKN2A/B, and activation of FGFR4, Ras, and Hedgehog (Hh) signaling. The CDKN2A/B tumor suppressor is deleted in most patient samples. FGFR4, which encodes a receptor tyrosine kinase, is activated in 20% of tumors, predominantly by amplification of mutant, activating FGFR4 alleles. Over 50% of patients had low-level gains of a region containing the Hh-pathway transcriptionfactor GLI1, and a gene expression pattern consistent with Hh-pathway activation. We also identified intragenic deletions affecting NF1, a tumor suppressor and inhibitor of Ras, in 15% of tumor samples. Deletion of NF1 and the presence of activating Ras mutations (in 42% of patients) were mutually exclusive, suggesting NF1 loss is an alternative and potentially common mechanism of Ras activation inERMS. Our data suggest that intermediate-risk ERMS is driven by a common set of genomic defects, a finding that has important implications for the application of targeted therapies to improve the treatment of children diagnosed with this disease.#CI- Copyright (c) 2011 Wiley-Liss, Inc.

The occurrence of metachronous adrenocortical carcinoma has rarely been described. We report a case of a child with virilizing adrenocortical metachronous tumors that, despite several metastases, presented long-term survival (15 years). We analyzed in this tumor IGF2, IGF1R and FGFR4 gene expression, and evaluated the presence of p.R337H germline p53 mutation and somatic CTNNB1 mutation. IGF2 gene was over-expressed in both left (Weiss score 5) and right (Weiss 7) adrenocortical tumors. IGF1R expression levels were higher in the right adrenocortical tumor. FGFR4 over-expression was also detected in the right adrenocortical tumor. In addition, this patient harbors the germline p.R337H p53 mutation and loss of heterozygosity (LOH) was detected in the tumors. No somatic CTNNB1 mutations were found in both tumors. In conclusion, we demonstrated in this unusual case the over-expression of growth signaling pathways, which are molecular mechanisms previously related to adrenocortical tumorigenesis. Furthermore, the absence of somatic CTNNB1 mutations, which is a molecular marker of poor prognosis in adults, might be related to the long-term survival of this patient.

BACKGROUND: Glioblastoma multiforme (GBM) is the most common malignant central nervous system neoplasm. Loss of heterozygosity (LOH) on chromosome 10q in thesetumors has been found to show variable association with prognosis. AIM: To evaluate LOH 10q status in cases of GBM, and to correlate these results with patient characteristics, other genetic alterations, and survival. MATERIAL AND METHODS: Fresh tumor tissue and blood samples were obtained for 25 cases of GBM diagnosed over a 2-year period. LOH 10q assay was performed on blood and tumor DNA by a PCR-based method using four microsatellite markers. TP53 mutation analysis and fluorescence in situ hybridization for epidermal growth factor receptor (EGFR) were performed. Histopathology was reviewed and clinical data were analyzed. RESULTS: LOH 10q was identified in 17 of 25 cases (68%). Losses were frequent with markers D10S1765 (12/20 informative cases; 60%) and D10S587 (12/17 informative cases; 70.5%) in the regions of 10q23.3 and 10q26.1, respectively. D10S540 for 10q25.1 showed LOH in 4/12 informative cases (33.3%) and D10S1770 for 10q26-ter in none of the 25 cases. LOH with D10S1765 at the PTEN gene locus was found to correlate with overall LOH 10q status (P = 0.001). LOH 10q was more common in patients older than 40 years (16/19, 84.2%) than in thosebelow (1/6, 16.7%) (P = 0.006). One of three pediatric patients included demonstrated LOH 10q. Survival rates for patients with LOH were lower than for patients with retained heterozygosity. CONCLUSION: LOH 10q is a frequent geneticabnormality in GBM in Indian patients, is seen more frequently in older adults, and its presence is associated with shorter survival. The single best marker to determine LOH 10q status is D10S1765 at the PTEN region.

The germline R337H mutation in the TP53 gene is considered to be responsible forthe increased incidence of adrenocortical tumors (ACTs) in children from Brazil.High level production of hormones in ACTs (>95%) cause virilization alone (60%),Cushing syndrome (<5%), the mixed type (30%), or other rarer manifestations. ACTprobably develops owing to events occurring during the final stages of intrauterine life based on the very common early onset of signs and symptoms shortly after birth. In this study, we determined by immunohistochemistry and enzyme assays whether placental alkaline phosphatase (PLAP) is expressed in pediatric ACTs. Immunohistochemical analysis revealed positive p53 expression in88% of the tested ACTs (29 of 33). PLAP was detected at a slightly lower frequency based on immunohistochemical (17 of 33, 51%) and enzyme activity analyses (9 of 16, 56%). In conclusion, probably at a certain time point during adrenocortical development (end of gestation to early postnatal period), some fetal zone cells survive owing to defective apoptosis and develop into childhoodACT, maintaining some characteristics of the embryonal period, such as PLAP expression. Further studies of PLAP should investigate the functional role, if any, of PLAP in such tumors.

Acute lymphoblastic leukemia (ALL) is the most frequent childhood tumor. Although the cure rate has increased dramatically over the past few years, the molecular and cellular biology of this disease is still not fully understood. Important factors affecting prognosis include age, leucocyte count, cytogenetic abnormalities, immunophenotype and sex. However, the role of cell kinetics, tumor associated genes and drug resistance have rarely been investigated in pediatric ALL. This preliminary study looks at these aspects in this disease. Immunocytochemical analysis of the tumor suppressor protein p53, the anti apoptotic protein bcl-2, the multidrug resistance (MDR) gene product P-glycoprotein and the proliferation marker, Ki-67 were done using appropriate monoclonal antibodies. A total of 88 previously untreated children with confirmed ALL diagnosis and 40 age matched controls were included in the study. Ki-67 was expressed in 81% and P-glycoprotein in 68% of ALL cases. P53 expression was observed in 68% and Bcl-2 in 50% of cases. Fifty percent of ALL cases also showed concomitant expression of bcl-2 and p53. Since wild-type p53 is known to negatively regulate the expression of bcl-2, the co-expression of these two proteins having contrasting functions suggests that the p53 may be of a mutant variety. In addition, the expression of p53 also correlates to the presence of the multidrug gene product P-glycoprotein. Control samples were negative for allthe four markers. P53, bcl-2 and P-glycoprotein can ALL influence chemotherapy resistance, the first two by regulating programmed cell death and the third by influencing intracellular drug levels. ALL patients are now being followed up toassess treatment response and to study the prognostic significance of the analyzed markers.

We sequenced 120 candidate genes in 187 high-risk childhood B-precursor acute lymphoblastic leukemias, the largest pediatric cancer genome sequencing effort reported to date. Integrated analysis of 179 validated somatic sequence mutations with genome-wide copy number alterations and gene expression profiles revealed ahigh frequency of recurrent somatic alterations in key signaling pathways, including B-cell development/differentiation (68% of cases), the TP53/RB tumor suppressor pathway (54%), Ras signaling (50%), and Janus kinases (11%). Recurrent mutations were also found in ETV6 (6 cases), TBL1XR1 (3), CREBBP (3), MUC4 (2), ASMTL (2), and ADARB2 (2). The frequency of mutations within the 4 major pathways varied markedly across genetic subtypes. Among 23 leukemias expressing a BCR-ABL1-like gene expression profile, 96% had somatic alterations in B-cell development/differentiation, 57% in JAK, and 52% in both pathways, whereas only 9% had Ras pathway mutations. In contrast, 21 cases defined by a distinct gene expression profile coupled with focal ERG deletion rarely had B-cell development/differentiation or JAK kinase alterations but had a high frequency (62%) of Ras signaling pathway mutations. These data extend the range of genes that are recurrently mutated in high-risk childhood B-precursor acute lymphoblastic leukemia and highlight important new therapeutic targets for selected patient subsets.

Li-Fraumeni syndrome (LFS) is a classic cancer predisposition disorder that is commonly associated with germline mutations of the p53 tumor suppressor gene. Examination of the wide spectrum of adult-onset and childhood cancers and the distribution of p53 mutations has led to a greater understanding of cancer genotype-phenotype correlations. However, the complex LFS phenotype is not readily explained by the simple identification of germline p53 mutations in affected individuals. Recent work has identified genetic events that modify the LFS phenotype. These include intragenic polymorphisms, mutations/polymorphisms of genes in the p53 regulatory pathway, as well as more global events such as aberrant copy number variation and telomere attrition. These genetic events may,in part, explain the breadth of tumor histiotypes within and across LFS families, the apparent accelerated age of onset within families, and the range of clinicaloutcomes among affected family members. This review will examine the clinical and genetic definitions of LFS and offer insight into how lessons learned from the study of this rare disorder may inform similar questions in other familial cancer syndromes.

Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis. The incidence of pediatric adrenocortical tumors (ACT) is remarkably high in Southern Brazil, where it is estimated to be 15 times greater than the world occurrence, due to a high frequency of a germline mutation (p.R337H) of the TP53 gene. Differently from adults, pediatric adrenocortical neoplasms with apparently poorprognosis based on histopathological features have often a good clinical outcome. A high Weiss score is definitely not a good predictor of survival in children, but it is much more discriminative of a poor outcome in adult tumors. Besides important differences in prognosis, adrenocortical tumorigenesis has distinct patterns between children and adults. In this review, we summarize recent data from ours and other Institutions, showing that the prognostic importance of molecular markers is striking different between pediatric and adult ACT. Although the majority of pediatric ACT are associated with p.R337H germline mutation, it is not a predictor of poor outcome in children and adolescents with ACT. On the other side, TP53 somatic mutations define a subgroup of adult ACC with differenttumorigenesis and unfavorable prognosis. IGF system has a central role in the malignant phenotype of ACT, but in adult tumors it is mediated by IGF2 over-expression and in pediatric tumors by IGF1R over-expression. Finally, SF1 over-expression is associated with decreased overall survival and recurrence-free survival in adult ACC, but not in the pediatric group. In conclusion, discriminating benign and malignant behavior is more challenging in pediatric ACT than in adult tumors.#CI- Copyright A(c) 2011 Elsevier Ireland Ltd. ALL rights reserved.

Although loss of p53 function and activation of canonical Wnt signaling cascadesare frequently coupled in cancer, the links between these two pathways remain unclear. We report that p53 transactivated microRNA-34 (miR-34), which consequently suppressed the transcriptional activity of beta-catenin-T cell factor and lymphoid enhancer factor (TCF/LEF) complexes by targeting the untranslated regions (UTRs) of a set of conserved targets in a network of genes encoding elements of the Wnt pathway. Loss of p53 function increased canonical Wnt signaling by alleviating miR-34-specific interactions with target UTRs, and miR-34 depletion relieved p53-mediated Wnt repression. Gene expression signatures reflecting the status of beta-catenin-TCF/LEF transcriptional activity in breastcancer and pediatric neuroblastoma patients were correlated with p53 and miR-34 functional status. Loss of p53 or miR-34 contributed to neoplastic progression by triggering the Wnt-dependent, tissue-invasive activity of colorectal cancer cells. Further, during development, miR-34 interactions with the beta-catenin UTR affected Xenopus body axis polarity and the expression of Wnt-dependent patterning genes. These data provide insight into the mechanisms by which a p53-miR-34 network restrains canonical Wnt signaling cascades in developing organisms and human cancer.

Although monoallelic expression (MAE) is a frequent genomic event in normal tissues, its role in tumorigenesis remains unclear. Here we carried out single-nucleotide polymorphism arrays on DNA and RNA from a large cohort of pediatric and adult brain tumor tissues to determine the genome-wide rate of MAE, its role in specific cancer-related genes, and the clinical consequences of MAE in brain tumors. We also used targeted genotyping to examine the role of tumor-related genes in brain tumor development and specifically examined the clinical consequences of MAE at TP53 and IDH1. The genome-wide rate of tumor MAEwas higher than in previously described normal tissue and increased with specific tumor grade. Oncogenes, but not tumor suppressors, exhibited significantly higher MAE in high-grade compared with low-grade tumors. This method identified nine novel genes highly associated with MAE. Within cancer-related genes, MAE was gene specific; hTERT was most significantly affected, with a higher frequency of MAE in adult and advanced tumors. Clinically, MAE at TP53 exists only in mutated tumors and increases with tumor aggressiveness. MAE toward the normal allele at IDH1 conferred worse survival even in IDH1 mutated tumors. Taken together, our findings suggest that MAE is tumor and gene specific, frequent in brain tumor subtypes, and may be associated with tumor progression/aggressiveness. Further exploration of MAE at relevant genes may contribute to better understanding of tumor development and determine survival in brain tumor patients.#CI- (c)2012 AACR.

BACKGROUND: MicroRNAs are small molecules which regulate gene expression post-transcriptionally and aberrant expression of several miRNAs is associated with neuroblastoma, a childhood cancer arising from precursor cells of the sympathetic nervous system. Amplification of the MYCN transcription factor characterizes the most clinically aggressive subtype of this disease, and although alteration of p53 signaling is not commonly found in primary tumors, deregulation of proteins involved in this pathway frequently arise in recurrent disease after pharmacological treatment. TH-MYCN is a well-characterized transgenic model of MYCN-driven neuroblastoma which recapitulates many clinicopathologic features of the human disease. Here, we evaluate the dysregulation of miRNAs in tumors from TH-MYCN mice that are either wild-type (TH-MYCN) or deficient (TH-MYCN/p53ER(TAM)) for the p53 tumor suppressor gene. PRINCIPAL FINDINGS: We analyzed the expression of 591 miRNAs in control (adrenal) and neuroblastoma tumor tissues derived from either TH-MYCN or TH-MYCN/p53ER(TAM) mice, respectively wild-type or deficient in p53. Comparing miRNA expression in tumor and control samples, we identified 159 differentially expressed miRNAs. Using data previously obtained from human neuroblastoma samples, we performed a comparison of miRNA expression between murine and human tumors to assess the concordance between murine and human expression data. Notably, the miR-17-5p-92 oncogenic polycistronic cluster, which is over-expressed in human MYCN amplifiedtumors, was over-expressed in mouse tumors. Moreover, analyzing miRNAs expression in a mouse model (TH-MYCN/p53ER(TAM)) possessing a transgenic p53 allele that drives the expression of an inactive protein, we identified miR-125b-3p and miR-676 as directly or indirectly regulated by the level of functional p53. SIGNIFICANCE: Our study represents the first miRNA profiling of an important mouse model of neuroblastoma. Similarities and differences in miRNAs expression between human and murine neuroblastoma were identified, providing important insight into the efficacy of this mouse model for assessing miRNA involvement inneuroblastoma and their potential effectiveness as therapeutic targets.

Adrenocortical tumors (ACT) are more frequent during childhood, but they can appear at any age. ACTs can be classified in functioning, nonfunctioning (mainlyobserved in adults) and mixed. The diagnosis is based on clinical, biochemical findings and imaging. In children, in order to classify ACT as benign or malignant, tumor staging classification is recommended. Regarding molecular markers some studies should be taken into account: besides TP53 mutations, previous studies have also provided evidences of IGF2 involvement in 90% of the malignant ACT. mutations altering exon 3 of CTNNB1 gene have been found in 6% ofchildhood ACTs. In addition, microRNAs can act as negative regulators of gene expression by targeting mRNA controlling cell growth, differentiation and apoptosis and have been implicated in adrenal tumorigenesis. High-throughput methods to analyze genome-wide expression have been developed over the last decade and identified a subset of tumors with good or poor prognosis. In the future, these studies can provide the basis of specific drug development, which can treat patients according to specific altered signaling pathway.

Li-Fraumeni syndrome (LFS) is a highly penetrant, autosomal dominant disorder where affected individuals carry a 50% risk of developing cancer before 30 yearsof age. It is most commonly associated with mutations in the tumour suppressor gene, TP53. Adrenocortical carcinoma (ACC) is a very rare paediatric cancer, andup to 80% of affected children are found to carry germline TP53 mutations. Hence, we propose using childhood ACC incidence as selection criteria for referral for TP53 mutation testing, independent of familial cancer history. Under the auspices of the Malaysian Society of Paediatric Haematology-Oncology, four eligible children diagnosed with ACC over a 30-month study period were referred for mutation testing. Three had a germline TP53 mutation. Subsequent TP53 testing inrelatives showed two inherited mutations and one de novo mutation. These findings strongly support paediatric ACC as a useful sentinel cancer for initiating a germline TP53/LFS detection programme, particularly in countries where the lack of structured oncogenetic practice precludes the identification of families withLFS features.#CI- (c) 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

BACKGROUND: Choroid plexus carcinoma (CPC) is an uncommon, aggressive, malignant, central nervous system neoplasm that typically occurs in children, presenting with the signs and symptoms of intracranial hypertension and cerebrospinal fluidobstruction. CASE REPORT: We report the case of a 2.5-year-old girl with CPC. The tumor was subtotally removed by microsurgery, followed by gamma knife radiosurgery for the residual lesion. H&E staining indicated that this was a rare case of CPC. Neuropathological studies, assayed by immunohistochemical staining,showed that the tumor sample was positive to antibodies against S-100, CgA, AE1/AE3 (cytokeratin), Ki-67, INI1 and TP53, and was negative to antibodies against Nestin, GFAP, CD133, EMA and AFP. Moreover, stainings for transthyretin and vimentin were focally positive. Interestingly, direct DNA sequencing of the paraffin-embedded tumor sample identified a novel R248Q mutation in the TP53 gene. In contrast to previous reports suggesting that TP53 germline mutations were associated with the pathogenesis of CPC, here we provide a rare case of CPCwith TP53 somatic mutation, as evidence that the peritumoral tissue possesses the non-mutant TP53 allele. CONCLUSIONS: Our finding suggests that TP53 somatic mutations, in addition to its germline mutations, may also be involved in the pathogenesis of pediatric CPC.

CONTEXT: childhood adrenocortical tumors (ACT) are rare malignancies, except in southern Brazil, where a higher incidence rate is associated to a high frequencyof the founder R337H TP53 mutation. To date, copy number alterations in these tumors have only been analyzed by low-resolution comparative genomic hybridization. OBJECTIVE: We analyzed an international series of 25 childhood ACT using high-resolution single nucleotide polymorphism arrays to: 1) detect focal copy number alterations highlighting candidate driver genes; and 2) compare genetic alterations between Brazilian patients carrying the R337H TP53 mutation and non-Brazilian patients. RESULTS: We identified 16 significantly recurrent chromosomal alterations (q-value < 0.05), the most frequent being -4q34, +9q33-q34, +19p, loss of heterozygosity (LOH) of chromosome 17 and 11p15. Focal amplifications and homozygous deletions comprising well-known oncogenes (MYC, MDM2, PDGFRA, KIT, MCL1, BCL2L1) and tumor suppressors (TP53, RB1, RPH3AL) were identified. In addition, eight focal deletions were detected at 4q34, defining asharp peak region around the noncoding RNA LINC00290 gene. Although non-Brazilian tumors with a mutated TP53 were similar to Brazilian tumors, those with a wild-type TP53 displayed distinct genomic profiles, with significantly fewer rearrangements (P = 0.019). In particular, three alterations (LOH of chromosome 17, +9q33-q34, and -4q34) were significantly more frequent in TP53-mutated samples. Finally, two of four TP53 wild-type tumors displayed as sole rearrangement a copy-neutral LOH of the imprinted region at 11p15, supporting a major role for this region in ACT development. CONCLUSIONS: Our findings highlight potential driver genes and cellular pathways implicated in childhood ACT and demonstrate the existence of different oncogenic routes in this pathology.

The tumor suppressor gene TP53 is the most commonly mutated gene in human cancer. The reported prevalence of mutations in rhabdomyosarcoma (RMS) varies widely, with recent larger studies suggesting that TP53 mutations in pediatric RMS may be extremely rare. Overexpression of MDM2 also attenuates p53 function. We have performed TP53 mutation/MDM2 amplification analyses in the largest series analyzed thus far, including DNA isolated from 37 alveolar and 38 embryonal RMS tumor samples obtained from the Cooperative Human Tissue Network (CHTN). Available samples were frozen tumor tissues (N = 48) and histopathology slides. TP53 mutations in exons 4-9 were analyzed by direct sequencing in ALL samples, and MDM2 amplification analysis was performed by differential PCR on a subset of22 samples. We found only one sample (1/75, 1.3%) carrying a TP53 mutation at codon 259 (p.D259Y) and no MDM2 amplification. Two SNPs in the TP53 pathway, associated with accelerated tumor onset in germline TP53 mutation carriers, (TP53 SNP72 (rs no. 1042522) and MDM2 SNP309 (rs no. 2279744)), were not found to confer earlier tumor onset. In conclusion, we confirm the extremely low prevalence of TP53 mutations/MDM2 amplifications in pediatric RMS (1.33% and 0%,respectively). The possible inactivation of p53 function by other mechanisms thus remains to be elucidated.

INTRODUCTION: The Li-Fraumeni syndrome (LFS) is an autosomal dominant hereditarydisorder associated with different tumor types in childhood and young adults. Approximately 70% of LFS cases contain germline mutations in the TP53 gene. We report a case of a family suspected of LFS. MATERIALS AND METHODS: The proband and four members of the family affected were diagnosed with cancer at an early age and they ALL died except the proband. Exons 5-9 from TP53 gene were analysedby direct amplification and sequencing in 7 family members. RESULTS: The analysis revealed a germline nonsense mutation in exon 8 at codon 306 of the codified region of the TP53 gene, causing a change of CGA to TGA (Arg-->Stop) in the proband, her mother, her cousin and her maternal uncle. Proband's maternal grandmother and aunt do not have the mutation. CONCLUSIONS: The members of this family that were studied meet the criteria of classic LFS and the described mutation increases their susceptibility to develop cancer. The proband's maternal grandfather died of lung cancer in 1993, and we believe that he was the carrier of the mutation in this family.

Medulloblastomas account for 20% of pediatric brain tumors. With an overall survival of 40%-70%, their treatment is still a challenge. The majority of medulloblastomas lack p53 mutations, but even in cancers retaining wild-type p53, the tumor surveillance function of p53 is inhibited by the oncoprotein MDM2. Deregulation of the MDM2/p53 balance leads to malignant transformation. Here, weanalyzed MDM2 mRNA and protein expression in primary medulloblastomas and normalcerebellum and assessed the mutational status of p53 and MDM2 expression in 6 medulloblastoma cell lines. MDM2 expression was elevated in medulloblastomas, compared with cerebellum. Four of 6 medulloblastoma cell lines expressed wild-type p53 and high levels of MDM2. The tumor-promoting p53-MDM2 interaction can be inhibited by the small molecule, nutlin-3, restoring p53 function. Targeting the p53-MDM2 axis using nutlin-3 significantly reduced cell viability and induced either cell cycle arrest or apoptosis and expression of the p53 target gene p21 in these 4 cell lines. In contrast, DAOY and UW-228 cells harboring TP53 mutations were almost unaffected by nutlin-3 treatment. MDM2 knockdown in medulloblastoma cells by siRNA mimicked nutlin-3 treatment, whereasexpression of dominant negative p53 abrogated nutlin-3 effects. Oral nutlin-3 treatment of mice with established medulloblastoma xenografts inhibited tumor growth and significantly increased survival. Thus, nutlin-3 reduced medulloblastoma cell viability in vitro and in vivo by re-activating p53 function. We suggest that inhibition of the MDM2-p53 interaction with nutlin-3 is a promising therapeutic option for medulloblastomas with functional p53 that should be further evaluated in clinical trials.

BACKGROUND: Li-Fraumeni-Syndrome (LFS) is an autosomal-dominant, inherited tumour predisposition syndrome associated with heterozygous germline mutations in the TP53 gene. Patients with LFS are at a high risk to develop early-onset breast cancer and multiple malignancies, among which sarcomas are the most common. A high incidence of childhood tumours and close to 100% penetrance has been described. Knowledge of the genetic status of the TP53 gene in these patients iscritical not only due to the increased risk of malignancies, but also because ofthe therapeutic implications, since a higher rate of radiation-induced secondarytumours in these patients has been observed. CASE REPORT: We report a patient with LFS harbouring heterozygous, pathogenic TP53 germline mutation, who was affected by four synchronous malignancies at the age of 40: a myxofibrosarcoma of the right upper arm, bilateral breast cancer and a periadrenal liposarcoma. Radiological treatments and a surveillance program were adjusted according to recommendations for LFS patients. CONCLUSION: Management of tumour treatment of patients with LFS is different to the general population because of their risk for secondary cancers in the radiation field. Screening procedures should take apossibly elevated risk for radiation induced cancer into account.

BACKGROUND: The Real-time PCR Array System is the ideal tool for analyzing the expression of a focused panel of genes. In this study, we will analyze the gene expression profile of pediatric acute myeloid leukemia with real-time PCR arrays. METHODS: Real-time PCR array was designed and tested firstly. Then gene expression profile of 11 pediatric AML and 10 normal controls was analyzed with real-time PCR arrays. We analyzed the expression data with MEV (Multi ExperimentView) cluster software. Datasets representing genes with altered expression profile derived from cluster analyses were imported into the Ingenuity pathway Analysis Tool. RESULTS: We designed and tested 88 real-time PCR primer pairs fora quantitative gene expression analysis of key genes involved in pediatric AML. The gene expression profile of pediatric AML is significantly different from normal control; there are 19 genes up-regulated and 25 genes down-regulated in pediatric AML. To investigate possible biological interactions of differently regulated genes, datasets representing genes with altered expression profile were imported into the Ingenuity pathway Analysis Tool. The results revealed 12 significant networks. Of these networks, Cellular Development, Cellular Growth and Proliferation, tumor Morphology was the highest rated network with 36 focus molecules and the significance score of 41. The IPA analysis also groups the differentially expressed genes into biological mechanisms that are related to hematological disease, cell death, cell growth and hematological system development. In the top canonical pathways, p53 and Huntington's disease signaling came out to be the top two most significant pathways with a p value of1.5E-8 and2.95E-7, respectively. CONCLUSIONS: The present study demonstrates thegene expression profile of pediatric AML is significantly different from normal control; there are 19 genes up-regulated and 25 genes down-regulated in pediatric AML. We found some genes dyes-regulated in pediatric AML for the first time as FASLG, HDAC4, HDAC7 and some HOX family genes. IPA analysis showed the top important pathways for pediatric AML are p53 and Huntington's disease signaling.This work may provide new clues of molecular mechanism in pediatric AML.

BACKGROUND: Dysembryoplastic Neuroepithelial tumours (DNT) are benign brain lesions arising during childhood that are characterized by early onset partial seizures, no neurological deficit and cortical location. Pathological diagnosis is easy when the glioneuronal element is present. Its absence might lead to the diagnosis of non-specific DNT or low-grade glioma (LGG). OBJECTIVE: The aim of this retrospective study was to analyse clinicopathological and molecular features of a series of cortical tumours, in order to find diagnostic and prognostic markers to better custom treatment next. METHODS: Twenty four children with cortical neuroepithelial tumour were included. Clinical and radiological data were collected. Histological diagnosis was reviewed for ALL patients. 1p19qand p53 status were obtained by FISH and immunohistochemistry respectively. IDH1-2 gene mutations were assessed by DNA sequencing. CGH-array was performed in 6/24 samples. Results: We recorded 13 DNT and 11 cortical LGG. Median age at surgery was 11.5 years. Overall survival was 100% and event-free survival at 10 years was 70%. No tumour displayed chromosomal alteration or 1p19q deletion or p53 expression. Only one patient with grade-II oligoastrocytoma had an IDH1 mutation. No statistical difference was found between the two populations in terms of age, sex, tumour location, type of surgical resection, disease progression and clinical status at last follow-up. Only the occurrence of septations on preoperative MRI was significantly associated with pathological features of DNT. CONCLUSION: Patients with DNT and cortical LGG share excellent outcome. Our genetic analysis could not distinguish DNT from LGG. In particular,CGH-array analysis was strictly normal in both tumor types. In attempt to find molecular markers, diagnosis of these lesions remains difficult when the glioneuronal element is lacking.

BACKGROUND: The treatment of tinea capitis using radiotherapy was introduced at the beginning of the twentieth century. In Israel, between 1949 and 1960, approximately 17,000 children underwent radiotherapy treatments for tinea capitis (actual numbers are probably higher due to irradiation in countries of origin asa prerequisite for immigration). Skin cancer presents a major problem for patients who underwent irradiation for the treatment of tinea capitis [aggressive biological behavior, multiple basal cell carcinomas (BCCs), up to 40 lesions in a single patient, with no predisposing condition such as Gorlin's or Bazex's syndromes]. There are ample data in the literature concerning the molecular changes in ultraviolet (UV) radiation-induced BCCs. However, similar data regarding ionizing radiation-induced BCCs are scarce. One work found higher rates of p53 and PTCH (both are tumor suppressor genes whose alterations are associated with BCC formation and frequency, but not biological behavior) abnormalities in post ionizing radiation BCCs. The absence of documented differences in gene expression that would account for a different biological behavior of radiotherapy-related BCCs, coupled with the aggressive and recurrent nature of these lesions, has propelled us to examine these differences by comparing gene expression in BCCs of the scalps of patients who were previously irradiated for tinea capitis in their childhood and of the scalps of patients who were not. METHODS: Tissue samples of excised scalp BCCs from seven previously irradiated patients (five male, two female) and seven not previously irradiated patients (six male, one female) were frozen upon excision and genetically analyzed using DNA microarray chips. RESULTS: No correlation was found between previous ionizing irradiation and gene expression. CONCLUSIONS: The negative results of this study, coupled with the observation of aggressive biological behavior of BCCs in previously irradiated patients merit further attention. Other explanations for the aggressive biological behavior of radiotherapy-induced BCCs come to mind. One such explanation could be that the difference between the groups lies not in thetumor itself, but in the host, who is more susceptible to the local destruction caused by the tumor due to changes in the surrounding tissue (e.g., impaired blood supply due to radiation, structural damage in seemingly healthy skin). This hypothesis will be the focus of further research. LEVEL OF EVIDENCE II: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Medulloblastomas are the most common malignant brain tumors in childhood. Emerging evidence suggests that medulloblastoma comprises at least four distinctdiseases (WNT, SHH, Group 3 and 4) with different biology, clinical presentation, and outcome, with especially poor prognosis in Group 3. The tight connection of biology and clinical behavior in patients emphasizes the need for subgroup-specific preclinical models in order to develop treatments tailored to each subgroup. Herein we report on the novel cell line HD-MB03, isolated from tumor material of a patient with metastasized Group 3 medulloblastoma, and preclinical testing of different histone deacetylase inhibitors (HDACis) in thismodel. HD-MB03 cells grow long term in vitro and form metastatic tumors in vivo upon orthotopic transplantation. HD-MB03 cells reflect the original Group 3 medulloblastoma at the histological and molecular level, showing large cell morphology, similar expression patterns for markers Ki67, p53, and glial fibrillary acidic protein (GFAP), a gene expression profile most closely matching Group 3 medulloblastomas, and persistence of typical molecular alterations, i.e., isochromosome 17q [i(17q)] and MYC amplification. Protein expression analysis ofHDACs 2, 5, 8, and 9 as well as the predictive marker HR23B showed intermediate to strong expression, suggesting sensitivity to HDACis. Indeed, treatment with HDACis Helminthosporium carbonum (HC)-toxin, vorinostat, and panobinostat revealed high sensitivity to this novel drug class, as well as a radiation-sensitizing effect with significantly increased cell death upon concomitant treatment. In summary, our data indicate that HD-MB03 is a suitable preclinical model for Group 3 medulloblastoma, and HDACis could represent a therapeutic option for this subgroup.

Precocious puberty represents a unique diagnostic problem in which imaging playsan important role. Development of secondary sex characteristics may result from inappropriate activation of the hypothalamic-pituitary axis with release of gonadotropin, or from gonadotropin-independent secretion of sex steroids by the adrenal glands or gonads. A variety of lesions can manifest with precocious puberty, including various central nervous system (CNS) lesions, adrenal lesions, and sex cord-stromal tumors of the testis or ovary. CNS lesions causing precocious puberty are much more common in boys than in girls and are well evaluated with brain magnetic resonance imaging. Neoplastic (hypothalamic-chiasmatic astrocytoma, suprasellar germinoma) and nonneoplastic (hypothalamic hamartoma, hydrocephalus, trauma, empty sella, infection, congenital midline anomalies) conditions may affect the function of the hypothalamic-pituitary axis. The adrenal cortex may produce sex hormones. Some adrenal cortical neoplasms (ACNs) in patients under 5 years of age are related to a mutation of the tumor suppressor gene p53 and represent a disease that is distinct from ACNs in older children and adults. Adrenal cortical hyperplasia secondary to an enzymatic defect in steroid biosynthesis causes virilization andsalt wasting, which usually manifest in the neonatal period; however, milder forms of the disease may manifest in childhood. Female precocious puberty may becaused by an autonomously functioning ovarian cyst or a juvenile granulosa cell tumor of the ovary. Male precocious puberty may be caused by a sex steroid-producing Leydig or Sertoli cell tumor of the testis. Ultrasonography isthe primary modality for evaluating the sex organs and may also be used to evaluate for adrenal abnormalities.

Although acute lymphocytic leukemia (ALL) is the most common childhood cancer, genetic predisposition to ALL remains poorly understood. Whole-exome sequencing was performed in an extended kindred in which five individuals had been diagnosed with leukemia. Analysis revealed a nonsense variant of TP53 which has been previously reported in families with sarcomas and other typical Li Fraumeni syndrome-associated cancers but never in a familial leukemia kindred. This unexpected finding enabled identification of an appropriate sibling bone marrow donor and illustrates that exome sequencing will reveal atypical clinical presentations of even well-studied genes.#CI- Copyright (c) 2012 Wiley Periodicals, Inc.

PURPOSE: pediatric adrenocortical carcinoma (ACC) is a rare and highly aggressive malignancy. Conventional chemotherapeutic agents have shown limited utility and are largely ineffective in treating children with advanced ACC. The lack of celllines and animal models of pediatric ACC has hampered the development of new therapies. Here we report the establishment of the first pediatric ACC xenograftmodel and the characterization of its sensitivity to selected chemotherapeutic agents. EXPERIMENTAL DESIGN: A tumor from an 11-year-old boy with previously untreated ACC was established as a subcutaneous xenograft in immunocompromised CB17 scid(-/-) mice. The patient harbored a germline TP53 G245C mutation, and the primary tumor showed loss of heterozygosity with retention of the mutated TP53 allele. Histopathology, DNA fingerprinting, gene expression profiling, and biochemical analyses of the xenograft were conducted and compared with the primary tumor and normal adrenal cortex. The second endpoint was to assess the preliminary antitumor activity of selected chemotherapeutic agents. RESULTS: Thexenograft maintained the histopathologic and molecular features of the primary tumor. Screening the xenograft for drug responsiveness showed that cisplatin hada potent antitumor effect. However, etoposide, doxorubicin, and a panel of othercommon cancer drugs had little or no antitumor activity, with the exception of topotecan, which was found to significantly inhibit tumor growth. Consistent with these preclinical findings, topotecan as a single agent in a child with relapsedACC resulted in disease stabilization. CONCLUSION: Our study established a novelTP53-associated pediatric ACC xenograft and identified topotecan as a potentially effective agent for treating children with this disease.#CI- (c)2013 AACR.

BACKGROUND: Adrenocortical carcinomas (ACCs) are among the most common childhoodcancers occurring in infants affected with the Li-Fraumeni and Li- Fraumeni-like(LFS/LFL) syndromes, which are caused by dominant germline mutations in the TP53gene. In Brazil, a particular mutation, occurring in the tetramerisation domain of the gene, p.R337H, is exceedingly common due to a founder effect and is strongly associated with ACC. In this report, we describe the phenotype and long-term clinical follow-up of a female child diagnosed with ACC and homozygousfor the TP53 p.R337H founder mutation. CASE PRESENTATION: At age 11 months, the patient was diagnosed with a virilising anaplastic adrenal cortical tumour, which was completely excised without disturbing the adrenal capsule. Family history was consistent with an LFL tumour pattern, and genotyping identified the TP53 p.R337H mutation in both alleles in genomic DNA from lymphocytes and fibroblasts. Haplotype analysis confirmed the occurrence of the mutation in the same founder haplotype previously described in other Brazilian patients. No other germline orsomatic TP53 mutations or rearrangements were identified. At age 9 years, the child was asymptomatic and had no evidence of endocrine derangements. Full body and brain magnetic resonance imaging (MRI) failed to detect any suspicious proliferative lesions, and cardiopulmonary exercise testing results were within the normal reference for the child's age, ruling out a major exercise capacity deficiency. CONCLUSION: This is the first clinical and aerobic functional capacity documentation of a patient who carries two mutant TP53 alleles and no wild-type allele. Our results support the hypothesis that TP53 p.R337H, the mostcommon TP53 mutation ever described in any population, is a conditional mutant. Furthermore, our observations over a long period of clinical follow-up suggest that TP53 p.R337H homozygotes do not have a more severe disease phenotype than do heterozygote carriers of the same mutation. Patients with the homozygous TP53 p.R337H genotype will require careful surveillance for lifetime cancer risk and for effects on metabolic capacity later in life.#FAU - Giacomazzi, Juliana

Neuroblastoma is a neuroendocrine tumour derived from neural crest cells and it remains a major therapeutic challenge in pediatric oncology. As response rates to chemotherapy are low, surgery remains the only effective treatment but since many tumors have metastasized at the time of diagnosis, curative surgery is rarely achieved. Consequently, a substantial need for new therapeutic options emerges. Quercetin a flavonoid, has been reported to lower the risk of several cancers. This study was designed to investigate its effects on apoptosis induction in theN2a, a mouse neuroblastoma cell line. The cell viability was determined by dimethyl thiazolyl tetrazolium bromide assay and diamidino-2-phenylindole staining was performed to confirm the apoptosis. The gene expression of bcl-w, p53, p27 and protein expression of caspases (3 and 9), bax, cytochrome-c were studied. This in vitro outcome suggests that quercetin can be used as a potent anti-cancer drug in future.

Among the solid tumors of childhood and adolescence, osteosarcoma (OS) represents the most prominent example of efficient aggressive chemotherapy with secondary surgical therapy. A specific subclassification of the tumor is indispensable andmust include recent results of cell biology. The co-distribution of different collagen types I-VI reflects the diverse differentiation of osteosarcoma cells, supporting the concept of a pluripotent mesenchymal cell to be the stem cell of the tumor. In contrast, osteonectin (SPARC) may not be considered as a reliable marker for osteosarcoma. The experience of special proteins being secreted by osteosarcoma cells is rather limited. Detailed molecular biological studies are still lacking. A loss of alleles on chromosome 17, particularly in the defined region 17p 13, can be observed in more than 75% of ALL OS, suggesting the contribution of a tumor suppressor gene, p53, located in that region. It is a 53kd nucleophosphoprotein binding the major transforming protein, the large T antigen of Simian Virus 40. Immunohistological results showed positive staining with the antibody Pab 240 in 13 of 18 cases. In one osteoblastic OS, a novel splice mutation resulting in a fusing of exon 5 directly to exon 7 was detected.RB1 gene is also of major importance for the tumorigenesis of OS. The multidrug resistance (mdr) is associated with a membrane-bound channel-forming transport protein, the P-glycoprotein. It is a conserved plasma membrane component of about 170 kd. Both the human isoforms mdr 1 and mdr 3 are localised in the long arm ofchromosome 7.(ABSTRACT TRUNCATED AT 250 WORDS)

In adults, loss of heterozygosity for DNA on 17p has been shown in high-grade anaplastic astrocytomas (AAs) and glioblastomas multiforme (GMs), and mutation of the TP53 tumor suppressor gene has been reported in ALL grades of astrocytomas. Little is known, however, about 17p deletion and TP53 mutation in juvenile pilocytic astrocytomas (JPAs), the most common low-grade tumors seen in children. To elucidate the genetic characteristics of pediatric high-grade astrocytomas and JPAs, we performed restriction fragment length polymorphism analysis with probesderived from 17p and TP53 mutational studies in 28 tumor specimens. Telomeric chromosome arm 17p markers 144-D6 and ABR were lost in 6 (75%) of 8 informative tumors classified as high-grade (7 AAs, 1 GM) and in 2 (10%) of 20 informative JPAs. Loss of 17p probes centromeric to the TP53 gene were also detected in 3 AAs and 5 JPAs. Four of the 6 (66%) JPAs with losses of 17p DNA sequences recurred rapidly despite aggressive therapy, whereas only 5 of the other 14 (36%) recurred. mutation of the TP53 gene was detected by polymerase chain reaction and denaturing gradient gel electrophoresis in only 1 JPA and 1 AA. These tumors were also examined for MDM2 gene amplification as an alternate inactivation mechanismfor TP53 gene function: no instances of alteration were identified. These results suggest that a gene or genes in addition to TP53 on 17p may be involved in the etiology or progression of high-grade astrocytomas and aggressive JPAs in children.(ABSTRACT TRUNCATED AT 250 WORDS)

Ten cases of hepatoblastoma were studied for overexpression of p53 protein by immunohistochemistry and for possible p53 gene mutation by single strand conformation polymorphism (SSCP) analysis and direct DNA sequencing of the polymerase chain reaction products. Only one case of the macrotrabecular type atstage IV showed overexpression of p53 protein. No DNA mobility shift was found in any of these cases studied by SSCP analysis. DNA sequencing performed on the case showing overexpression of p53 protein revealed no mutation within exons 5 to 8. The associated adrenal cortical carcinoma of the same case also showed overexpression of p53 protein, but no mutation of the p53 gene. These results indicate that mutation of the p53 gene is infrequent in hepatoblastoma. This observation supports the view that mutation of the p53 gene is not as important in the oncogenesis of childhood neoplasms as in adult cancers.

We investigated the possibility that a proportion of children with sporadic rhabdomyosarcoma (RMS) carry constitutional mutations of the p53 tumor suppressor gene. 33 patients with sporadic RMS at two large outpatient pediatric oncology clinics submitted blood samples. Genomic DNA was extracted from peripheral bloodleukocytes and PCR was used to amplify exons 2-11 of the p53 gene. Amplified genomic DNA was screened for the presence of germline p53 mutations using single-strand conformation polymorphism (SSCP) analysis. The DNA sequence of those samples that showed aberrant migration of bands on SSCP analysis was determined to identify the precise nature of the gene mutations. Patient recordswere reviewed to assess clinical correlates of the mutant p53 carrier state. Heterozygous constitutional mutations were detected in 3/33 patient samples screened. Two of these missense mutations are located in exon 7 and one in exon 8 of the p53 gene. The presence of mutations was not correlated with tumor histology, stage, or site. However, an association between young age at diagnosis and presence of a constitutional p53 mutation was noted: 3/13 children under theage of 3 yr at diagnosis carried mutations, whereas none of 20 children over 3 yr of age at diagnosis harbored a detectable constitutional mutation. These resultsin children with RMS corroborates previous findings in other clinical settings suggesting that the mutant p53 carrier state may predispose individuals to malignancy at an early age. Although this study did not assess whether the mutations were preexisting or new germline alterations, assessment of close relatives of RMS patients for cancer risk and predictive genetic testing may be indicated.

Neuroblastoma (NB), a tumor arising from the sympathetic nervous system, is one of the most common malignancies in childhood. Several recent reports on the p53 genotype found virtually exclusive wild-type status in primary tumors, and it was postulated that p53 plays no role in the development of NB. Here, however, we report that the vast majority of undifferentiated NBs exhibit abnormal cytoplasmic sequestration of wild-type p53. This inability of p53 to translocateto the nucleus presumably prevents the protein from functioning as a suppressor.Thirty of 31 cases (96%) of undifferentiated NB showed elevated levels of wild-type p53 in the cytoplasm of ALL tumor cells concomittant with a lack of nuclear staining. p53 immunoprecipitation from tumor tissues showed a 4.5- to 8-fold increase over normal protein levels. ALL of 10 tumors analyzed harbored wild-type p53 by direct sequencing of full-length cDNA and Southern blot. In addition, no MDM-2 gene amplification was seen in ALL 11 tumors analyzed. In contrast, no p53 abnormality was detected in 14 differentiated ganglioneuroblastomas and 1 benign ganglioneuroma. We conclude that loss of p53 function seems to play a major role in the tumorigenesis of undifferentiated NB.This tumor might abrogate the transactivating function of p53 by inhibiting its access to the nucleus, rather than by gene mutation. Importantly, our results suggest that (i) this could be a general mechanism for p53 inactivation not limited to breast cancer (where we first described it) and that (ii) it is foundin a tumor previously not thought to be affected by p53 alteration.

The p53 gene product is required for activation of an apoptotic pathway triggered by oncogenes and cytotoxic agents. Wilms' tumor, a pediatric renal malignancy, provides a paradigm for evaluating genetic events involved in tumor progression.This malignancy is generally not associated with p53 mutations, and even in advanced disease states is quite responsive to current treatment regimens. The anaplastic histological variant of Wilms' tumor, however, is frequently associated with p53 gene mutations and shows poor prognosis. We analyzed seven Wilms' tumors for which we had paired samples from nonanaplastic and anaplastic regions. p53 mutations were detected in six of these tumors, five of which demonstrated mutations restricted to anaplastic regions. Nonanaplastic cells of the sixth sample were heterozygous for a p53 mutation, whereas the anaplastic area of this tumor showed reduction to homozygosity. These results indicate thatprogression to anaplasia is associated with clonal expansion of cells which haveacquired a p53 mutation. We demonstrated that tumor cells with p53 mutations show attenuated apoptosis, suggesting that such lesions may provide a selective advantage in vivo by decreasing cell death.

The p53 gene codes for a nuclear phosphoprotein which is capable of modulating the expression of certain genes implicated in the regulation of cell division. The mutation of an allele on the p53 gene with loss of the healthy allele, in different tissues such as lung, larynx, bladder, liver, skin, colon and breast, which may or may not be exposed to chemical or physical carcinogens (tobacco, radon, ultraviolet, aflatoxin B1), is associated with the occurrence of cancer. Indeed, the mutated p53 protein loses its anti-proliferative properties favouring a de-regulation of cellular multiplication with the accumulation of genetic aberrations. The homozygous deletion of the p53 gene in germ cells in the members of certain family cancers (Li-Fraumeni syndrome) leads to an increased incidenceof cancers in the child or young adult. The most frequent mutations of the p53 gene end in a stabilisation of the mutated protein with immuno-histochemical nuclear marking of the cells carrying such an alteration. In certain patients this stabilisation of the mutated protein ends in auto-immunisation with anti-p53 serum antibodies. Bronchial cancer is a cancer of which the mutations of p53 arethe most frequent (45-65% of bronchial cancer) as result of the mutagenic effectof tobacco smoke. These mutations seem to be associated with a bad prognosis andindeed to chemo-and radiotherapeutic resistance. The early diagnosis of p53 alterations (in dysplastic lesions or tumours which are only slightly developed)would enable new therapeutic interventions in bronchial cancer such as gene therapy or radio-immunotherapy to either restore the p53 gene to normality or toeliminate the cells expressing the mutated p53 protein respectively.

The cases of two young male siblings independently developing unilateral Wilms' tumors and brain tumors are reported. The renal tumors were resected; the first child was treated with chemotherapy and the second child was given additional radiotherapy. Five years after treatment, both children developed a second primary neuroectodermal tumor. ALL four tumors showed a high proliferative activity, and rapidly progressing disease led to the death of the first child. Histopathological and molecular studies were carried out on ALL four neoplasms. No functionally relevant mutation was found in selected exons of the p53, K-ras and WT1 gene loci of tumor and germ line DNA. Since additional family members had developed brain tumors and carcinomas, this peculiar association of neoplasms may be due to germ line mutation of a hitherto unidentified oncogene acting in a recessive or weakly dominant fashion.

The wild-type (wt) p53 tumor suppressor gene is commonly inactivated in human malignancies, either by mutations or by loss of expression. An additional proposed mechanism for inactivation of wt-p53 is amplification of the murine double minute 2 (MDM2) gene and overexpression of the MDM2 protein, which binds to p53 and eliminates its tumor suppressor function. To investigate a potential role for MDM2 in the inactivation of wt-p53 in pediatric acute lymphoblastic leukemia (ALL), we examined the expression of MDM2 and p53, as well as the occurrence of p53 mutations and possible amplification of the MDM2 gene, in 19 pediatric ALL cell lines and one pediatric acute myelogenous leukemia (AML) line. Although we did not find significant amplification of the MDM2 gene in any of the leukemic lines, we detected overexpression of MDM2 in ALL 10 lines that expressed wt-p53. Of the 10 lines without overexpression of the MDM2 gene, six (including the AML line) did not express p53, and four expressed mutant p53 with single point mutations in exons 7 and 8. To determine whether primary leukemic cells showed a similar correlation, we analyzed the original cryopreserved leukemic bone marrow cells from seven patients from whom cell lines were established. We obtained similar results from both the primary leukemic cells and the corresponding cell lines: overexpression of MDM2 was present in primary cells that expressed wt-p53 but not in cells that lacked expression of wt-p53. These findings suggest an important role for MDM2 in the pathogenesis of pediatric ALLin which leukemic cells express wt-p53.

Loss of heterozygosity is common for the short arm of chromosome 17 in medulloblastomas, and putative medulloblastoma suppressor loci have been localized to 17p13. The colocalization of the p53 tumor suppressor gene to 17p13raises the possibility that its mutant alleles may play a role in the malignant transformation of "medulloblasts." mutations and deletions of the p53 gene have been described in many tumor types and in the germline of some individuals with the Li-Fraumeni syndrome, but reports on the status of the p53 and mdm2 (a gene coding for a p53-associated protein reportedly amplified in human sarcomas) genes in medulloblastomas are few and an indication of their roles, if any, in the etiology of this important childhood tumor has yet to emerge. Here we have analyzed polymerase chain reaction-amplified products of exons 4-9 (95% of reported p53 mutations occur within this region) of the p53 gene in 9 medulloblastomas for potential mutations using the technique of single strand conformation polymorphism analysis and DNA sequencing. We found only one mutation, an A-T to T-A transversion involving the second base of codon 285 and resulting in the substitution of valine for glutamic acid, amplification of the mdm2 gene could be detected in zero of eight of these tumors. These findings suggest that genetic events associated with the inactivation of p53 gene occur in only a minor subset of medulloblastomas.

BACKGROUND: Adrenocortical carcinoma (ADCC) is a rare childhood cancer, affecting three of 1 million children younger than 16 years old in the United States. ADCCmay be found in association with the Li-Fraumeni and Beckwith-Wiedemann syndromes. children with ADCC are also at substantially increased risk of secondprimary cancers. Because of these associations, it is believed that the genetic basis for ADCC is stronger than for most childhood malignancies. Germline mutations of the TP53 tumor suppressor gene are associated with cancer predisposition in families with the Li-Fraumeni syndrome as well as in individuals with sporadically occurring component tumors of the syndrome. PURPOSE: We investigated the possibility that germline TP53 gene alterations existed in children with ADCC. METHODS: Sixteen children with ADCC under the ageof 18 were identified from searches of medial oncology records at three Canadianhospitals. Eleven of these 16 patients identified were alive. The mean age at diagnosis was 4.8 years (range, 1-17 years). Family histories were obtained for 11 unselected children with ADCC (six girls and five boys). Pathologic confirmation of tumor diagnosis was obtained from the medical records. Using single-strand conformational polymorphism analysis followed by single-strand DNAsequencing, genomic DNA extracted from whole blood was analyzed for the presenceof TP53 mutations for six living ADCC patients. RESULTS: Three of six (50%) children were found to carry germline TP53 mutations in exons 5, 6, and 7, respectively. Both wild-type and mutant alleles were identified in ALL three TP53 sequences, indicating that the patients were heterozygous for germline TP53 mutations. None of these children was from a family with the Li-Fraumeni syndrome. The mutation in one child was shown to be inherited from the mother, who subsequently developed breast cancer. A striking excess of cancer was found in one family of a patient carrying wild-type TP53. CONCLUSIONS: Our observationof a high frequency of germline TP53 mutations in children with sporadic ADCC suggests that these children may represent probands with which to ascertain Li-Fraumeni syndrome families. It may be reasonable for children with adrenocortical carcinoma to be candidates for germline TP53 analysis. In light of the wealth of information in the Li-Fraumeni literature that associates germlineTP53 mutations with a variety of malignancies, this testing may have important consequences for risk assessment for other close relatives, including early-onset breast cancer in the mothers.

PURPOSE: We report a case of adrenal cortical carcinoma in an infant, which was incidentally discovered by renal sonography after a urinary tract infection. Theprevious death of a sibling after rhabdomyosarcoma in infancy prompted a search for a heritable p53 tumor suppressor gene mutation in this family. PATIENTS AND METHODS: Starting with frozen adrenal carcinoma tissue, polymerase chain reaction (PCR) amplification followed by direct sequencing of exons 4-8 of p53 was used to search for a mutation. When a mutation was identified in exon 6 of the tumor p53sequence, PCR amplification and direct sequencing of exon 6 alone was then performed on DNA from peripheral blood lymphocytes (PBLs) of ALL immediate family members to determine whether a germline mutation was present. A different set ofprimers was used by a second laboratory at our institution to independently confirm the presence of the mutation in the adrenal carcinoma and in paraffin-embedded rhabdomyosarcoma tissue of the deceased sibling. RESULTS: A C-to-T transition was identified at a CpG site in codon 196 resulting in a change from arginine to a stop codon (CGA to TGA). The identical mutation, present as the sole p53 allele in the tumor DNA samples and in the heterozygous state with wild type p53 allele in DNA from PBLs (germline), was found in the adrenal carcinoma, the rhabdomyosarcoma, and the PBLs of the tumor-bearing child and herhealthy father and 5-year-old brother. This nonsense mutation of p53 has never before been reported in the germline. The extended pedigree showed only one known additional cancer. CONCLUSIONS: A novel germline p53 mutation was identified by investigation of a sibling pair with cancers associated with the Li-Fraumeni syndrome in a family with an otherwise negative history for cancer. The implications of this case for identification of carriers of p53 germline mutations and their clinical management are discussed.

PURPOSE: We report a case of adrenal cortical carcinoma in an infant, which was incidentally discovered by renal sonography after a urinary tract infection. Theprevious death of a sibling after rhabdomyosarcoma in infancy prompted a search for a heritable p53 tumor suppressor gene mutation in this family. PATIENTS AND METHODS: Starting with frozen adrenal carcinoma tissue, polymerase chain reaction (PCR) amplification followed by direct sequencing of exons 4-8 of p53 was used to search for a mutation. When a mutation was identified in exon 6 of the tumor p53sequence, PCR amplification and direct sequencing of exon 6 alone was then performed on DNA from peripheral blood lymphocytes (PBLs) of ALL immediate family members to determine whether a germline mutation was present. A different set ofprimers was used by a second laboratory at our institution to independently confirm the presence of the mutation in the adrenal carcinoma and in paraffin-embedded rhabdomyosarcoma tissue of the deceased sibling. RESULTS: A C-to-T transition was identified at a CpG site in codon 196 resulting in a change from arginine to a stop codon (CGA to TGA). The identical mutation, present as the sole p53 allele in the tumor DNA samples and in the heterozygous state with wild type p53 allele in DNA from PBLs (germline), was found in the adrenal carcinoma, the rhabdomyosarcoma, and the PBLs of the tumor-bearing child and herhealthy father and 5-year-old brother. This nonsense mutation of p53 has never before been reported in the germline. The extended pedigree showed only one known additional cancer. CONCLUSIONS: A novel germline p53 mutation was identified by investigation of a sibling pair with cancers associated with the Li-Fraumeni syndrome in a family with an otherwise negative history for cancer. The implications of this case for identification of carriers of p53 germline mutations and their clinical management are discussed.

mutations in the p53 gene, which codes for a cell division regulatory protein, have been identified in approximately one-third of adult astrocytomas. We evaluated 35 astrocytic tumors (17 pilocytic, 4 diffuse low grade, 12 anaplastic, and 2 glioblastoma) in pediatric patients for p53 mutations, using polymerase chain reaction-single-stranded conformation polymorphism analysis as a screeningtechnique. Additionally, those tumors identified with homozygosity in the area of the p53 gene on chromosome 17 by Southern blotting were sequenced to look for p53 mutations. No tumors were identified with polymerase chain reaction-single-stranded conformation polymorphism analysis shifts indicative ofmutations in the p53 gene. Five of 21 tumors were homozygous in the region of the p53 gene on chromosome 17; no mutations in exons 5 to 8 were found in any of these tumors. The frequency of p53 mutation in pediatric astrocytomas is significantly less than the frequency for adult tumors, regardless of tumor grade. Furthermore, the frequency of p53 mutations in high-grade astrocytomas issignificantly lower in pediatric tumors than in adult tumors. These results suggest that p53 is not important in the oncogenesis of pediatric astrocytomas. Oncogenesis in pediatric astrocytomas may occur by different mechanisms than those of similar tumors in adults.

The eponym Li-Fraumeni syndrome is given to a particular form of cancer-prone family in which the main encountered tumors are sarcomas occurring in childhood and breast cancers affecting young adult females. There is also an increased frequency of cerebral tumors, leukemias and adrenal carcinomas among these families. The transmission of the cancer-proneness is autosomal dominant and related to the loss of function of the p53 tumor suppressor gene located on the short arm of the chromosome 17. The related p53 protein is identified but its precise mechanism of action and its regulation are still unclear. It seems to activate the genes which negatively regulate the multiplication of the cell and to act as a factor of transcription. A germline mutation of the p53 gene must belooked for in every cancer-prone family but also in case of multifocal tumors, particularly osteosarcomas and glioblastomas, and in case of second malignant neoplasm. This is of major scientific as well clinical interest. Indeed, the study of new families will help to better understand the molecular mechanisms underlying the syndrome. For the family itself this allow to identify the cancerprone members and to offer them preventive measures and early detection of cancers, particularly early breast cancer detection.

Brain stem gliomas are pediatric astrocytomas that histologically resemble adultsupratentorial astrocytomas such as glioblastomas multiforme (GBM). Our molecular genetic studies have suggested that adult GBM can be divided into two genetic subsets: tumors with p53 tumor suppressor gene mutations and chromosome 17p lossthat occur more commonly in younger patients; and tumors with epidermal growth factor receptor (EGFR) gene amplification that occur more commonly in older patients. Brain stem gliomas have not been studied since biopsies of these tumors are rare and extremely small. We investigated the molecular genetic composition of seven brain stem glioblastomas (two small biopsies, five autopsies) using polymerase chain reaction (PCR) assays for chromosomal loss, gene mutation and gene amplification. Four cases lost portions of chromosome 17p that included thep53 gene. These four cases and one additional case had mutations in the p53 gene. None of the cases showed amplification of the EGFR gene. Allelic losses of the long arm of chromosome 10 were noted in four cases. These results suggest similarities between pediatric brain stem glioblastomas and those GBM that occurin younger adult patients, and confirm the utility of PCR-based means of studying small and archival brain tumor specimens.

Glial tumors of ALL grades and histological types from 72 adults and 48 childrenwere analyzed for mutations of the TP53 gene, loss of heterozygosity (LOH) for 17p, and accumulation of TP53 protein to determine whether the incidence and type of TP53 alterations differ among tumors of different histological type and between tumors from adults and children. These tumors were also evaluated for LOH for chromosome 10 and for amplification of the epidermal growth factor receptor,C-MYC, N-MYC, GLI, platelet-derived growth factor receptor-alpha, and murine double minute 2 genes to determine the patterns of molecular alterations involved in the progression of these neoplasms. Seventeen of the 120 tumors contained mutations of the TP53 gene. One of the tumors with TP53 gene mutation was from one of the 48 patients less than 18 years of age. Twelve of the 17 tumors with mutations occurred among the 27 patients in the 18-45-year age group, while 4 tumors with mutations were among the 45 patients more than 45 years old. There was also an increased incidence of TP53 mutation in patients with anaplastic astrocytoma histology. However, no significant association between presence of TP53 mutation and patient survival was observed. These studies demonstrate that TP53 gene mutations are a common mechanism for glial cell neoplasms in the 18-45-year age group but are unrelated to progression and advanced histological grade. LOH for chromosome 10 and gene amplification, however, occurring in 82 and 40%, respectively, of glioblastoma multiforme, whether seen alone or along with TP53 gene alterations, are related to advanced histological grade of the tumor. In childhood gliomas, in contrast, TP53 gene alterations, LOH for 17p and 10q, and gene amplification are uncommon in tumors of ALL grades, suggesting that presently unknown mechanisms are responsible for the genesis and progression of these tumors.

PURPOSE: We investigated the possibility that a significant proportion of children with osteosarcoma harbor germline mutations of the p53 tumor suppressorgene and, therefore, this subgroup of pediatric cancer patients should be considered for large-scale predictive testing. PATIENTS AND METHODS: Genomic DNAextracted from peripheral-blood leukocytes from 235 unselected children with osteosarcoma from 33 institutions were screened for the presence of germline p53mutations using constant denaturant gel electrophoresis (CDGE). Exons 5 through 8 were evaluated in ALL patients and exon 2 and exon 9 were analyzed in 59 and 95 patients, respectively. Those samples that showed aberrant migration on CDGE were sequenced or analyzed by restriction enzyme digestion of polymerase chain reaction (PCR) products to confirm the nature of the gene alteration. RESULTS: In 18 samples, CDGE showed fragments of the p53 gene with altered electrophoretic mobilities compared with wild-type p53. DNA sequencing showed that 11 samples had an identical, previously described polymorphism. The other seven contained heterozygous p53 mutations located in exon 5 (n = 3), exon 6 (n = 1), exon 7 (n = 1), and exon 8 (n = 2). Six alterations were missense mutations and one was a nonsense mutation. Three of these patients had first-degree relatives with cancer. One of these three kindreds had a family history consistent with Li-Fraumeni syndrome (LFS). CONCLUSION: We identified germline p53 mutations in seven of 235 (3.0%) children with osteosarcoma. Four of these mutations were found in patients who did not have first-degree relatives with cancer. Although genetic transmission of the altered p53 gene could not be tested in this survey because of how it was designed, it is possible that predictive testing for p53 mutations could identify unaffected relatives of gene carriers who also have a high risk for the development of cancer. This study provides evidence for the importance of considering children with osteosarcoma for predictive testing for germline p53 mutations.

PURPOSE: We investigated the possibility that a significant proportion of children with osteosarcoma harbor germline mutations of the p53 tumor suppressorgene and, therefore, this subgroup of pediatric cancer patients should be considered for large-scale predictive testing. PATIENTS AND METHODS: Genomic DNAextracted from peripheral-blood leukocytes from 235 unselected children with osteosarcoma from 33 institutions were screened for the presence of germline p53mutations using constant denaturant gel electrophoresis (CDGE). Exons 5 through 8 were evaluated in ALL patients and exon 2 and exon 9 were analyzed in 59 and 95 patients, respectively. Those samples that showed aberrant migration on CDGE were sequenced or analyzed by restriction enzyme digestion of polymerase chain reaction (PCR) products to confirm the nature of the gene alteration. RESULTS: In 18 samples, CDGE showed fragments of the p53 gene with altered electrophoretic mobilities compared with wild-type p53. DNA sequencing showed that 11 samples had an identical, previously described polymorphism. The other seven contained heterozygous p53 mutations located in exon 5 (n = 3), exon 6 (n = 1), exon 7 (n = 1), and exon 8 (n = 2). Six alterations were missense mutations and one was a nonsense mutation. Three of these patients had first-degree relatives with cancer. One of these three kindreds had a family history consistent with Li-Fraumeni syndrome (LFS). CONCLUSION: We identified germline p53 mutations in seven of 235 (3.0%) children with osteosarcoma. Four of these mutations were found in patients who did not have first-degree relatives with cancer. Although genetic transmission of the altered p53 gene could not be tested in this survey because of how it was designed, it is possible that predictive testing for p53 mutations could identify unaffected relatives of gene carriers who also have a high risk for the development of cancer. This study provides evidence for the importance of considering children with osteosarcoma for predictive testing for germline p53 mutations.

mutations of the p53 tumor suppressor gene occur frequently in a variety of adult-onset tumors, including colon, breast, lung, and brain, yet are infrequently identified in pediatric malignancies. Wilms' tumor, a common solid tumor of childhood, can be associated with mutations of the WT1 gene. Alterations of the p53 gene have been shown to modulate the ability of WT1 to transactivate its targets. Although positive p53 immunostaining has been demonstrated in Wilms' tumors, the correlation to p53 gene mutations is not clear. We examined Wilms' tumor samples for p53 mutations utilizing polymerase chain reaction-single-strand conformation polymorphism analysis and single-strand DNA sequencing. mutations in the coding region of the p53 gene were demonstrated in 2 of 21 (9.5%) Wilms' tumors. Each mutation yielded a substitution of amino acid residues. One mutation was located in exon 6 and the other in exon 7. Both mutations were found in tumors from patients with advanced stage disease. Focal anaplasia was demonstrated in one of these tumors. Our data suggest that although p53 mutations occur infrequently in Wilms' tumor, they may be associated with advanced disease.

High levels of expression of the p53 protein and gene mutations have been described in adult hepatocellular carcinomas. It has been postulated that specific mutations in exon 7 may be caused by aflatoxin exposure. To determine whether p53 mutations occur in childhood liver cancer unassociated with aflatoxin exposure or hepatitis B virus (HBV) infection, we have analyzed three histologically distinct tumor types. Two techniques were used to access p53 in the tumors: (1) expression studies of the p53 protein were performed using the polyclonal antibody CM1 and immunohistochemistry, and (2) DNA sequencing was performed. p53 Protein was detectable by immunohistochemistry in 10 of 15 hepatoblastomas, six of nine hepatocellular carcinomas, and one of one embryonalsarcomas. Solid phase single-stranded DNA sequencing across exons 5 through 9 showed normal sequence in ALL cases. These results indicate that p53 is overexpressed in a majority of childhood liver cancers, but this abnormal p53 expression does not seem to be caused by mutations in the p53 gene.

Medulloblastoma (MB) represents the most frequent malignant brain tumor of childhood but only a few cell lines and animal models of this primitive neuroectodermal tumor (PNET) have thus far been established. Using specific cellculture conditions, we were able to derive four human MB cell lines (MHH-MED-1-4) as well as a cell line from a spinal PNET (MHH-PNET-5). The four MB cell lines grew in suspension as floating cell aggregates or as slightly adherent cells. They consisted of undifferentiated cells that did not express markers of late neuronal or glial lineages such as neurofilaments or glial fibrillary acidic protein. They also lacked expression of major histocompatibility complex class Ior II antigens on the cell surface. ALL four MB lines were positive for vimentinand neuron-specific enolase, whereas synaptophysin, neural cell adhesion molecule, galactocerebroside, GD2, GD3, and the A2B5 antigen were expressed inconsistently. In contrast, MHH-PNET-5 grew as adherent monolayer and expressedmajor histocompatibility complex class I antigen. By cytogenetic analysis, the lines were near diploid with clonal aberrations. The MB lines showed no losses of chromosome arm 17p by either cytogenetic or microsatellite analyses. The cell line MHH-MED-2 exhibited double minute chromosomes, amplification of the c-myc gene, and overexpression of c-myc mRNA and protein. N-myc, p53, and Rb protein expression were unaltered. ALL four continuously passaged MB cell lines and the MHH-PNET-5 line were xenotransplanted s.c. into athymic mice; three of four MB lines and the spinal PNET line gave rise to tumors. These cell lines will be useful tools for biological and preclinical studies on PNETs.

Neuroblastoma is a common childhood malignancy of the sympathetic nervous system. mutations in p53, a tumor suppressor gene located on the short arm of chromosome17, are one of the most common genetic lesions in human cancers. The evidence for trisomies of 17q with loss of 17p in some cases of neuroblastoma led us to consider whether p53 mutations might contribute to the onset and progression of this malignancy. In this study, primary tumors from 38 neuroblastoma patients were screened for mutations within the coding exons of the p53 gene by single-strand conformation polymorphism analysis, and potential mutations were further analyzed by nucleotide sequence analysis. Previously described sequence variations were detected in many of the tumors, including a silent polymorphism at codon 213 (CGA to CGG) and the nontransforming Pro to Arg substitution at codon 72 (CCC to CGC). However, no other sequence variations were detected within the coding portions of the p53 gene. This finding suggests that p53 mutations donot contribute to the etiology of neuroblastoma and that the chromosome 17 alterations observed in neuroblastoma involve genes which are distinct from the p53 locus.

mutations in the p53 tumor suppressor gene occur in > 50% of human malignancies,but are exceedingly rare in benign tumors. The malignant potential of fibrous tumors of children may be unpredictable at microscopic examination. We thereforesought to determine whether malignant fibrous tumors could be distinguished fromtheir benign counterparts by the presence of mutations in p53. We screened 27 fibrous tumor samples from 20 young patients. tumors were classified as benign, borderline, or malignant by conventional microscopic criteria. RNA extracted from each specimen was used as the template for reverse transcription followed by polymerase chain reaction (PCR) amplification, with six pairs of primers covering the whole coding region of the p53 gene. ALL PCR products were screened for the presence of mutations using single-strand conformation polymorphism analysis. Inaddition, PCR products encompassing exons 5-9, the sites of the most frequent mutations in human tumors, were sequenced directly. Both methods detected a single point mutation in a highly malignant tumor (malignant fibrous histiocytoma). The mutation was a silent one at codon 36 (CCG-CCA, Pro-Pro). We conclude that p53 mutations are infrequent in childhood fibrous tumors, consistent with previous observations of low malignant potential (< 10%) and better prognosis in this tumor group. Therefore, screening for p53 mutations is not a useful prognostic indicator in fibrous tumors with borderline pattern at microscopic examination.

mutation of the p53 tumor suppressor gene frequently occurs in a variety of tumors including lung, breast, gastrointestinal, and brain, as well as lymphomas-leukemias. Neuroblastoma, one of the most common solid tumors in childhood, often has amplification of the N-myc gene. We examined for mutations of the p53 tumor suppressor gene by single-strand conformational polymorphism using polymerase chain reaction products and direct sequencing method in neuroblastoma; in addition, we assessed the relationship between p53 mutation and N-myc gene amplification in the disease. Of 86 DNA samples from patients with neuroblastoma, two mutations (2%) were found in the coding region of the p53 gene. Each mutation caused a substitution of amino acid residues. One mutation was located in exon 5, and another was in exon 6. N-myc gene was amplified in 26% of the samples. No p53 mutations were found in neuroblastoma samples with N-myc amplification. In the two individuals, p53 mutations appeared as their disease became more progressive. The neurofibromatosis 1 (NF1) gene is frequently abnormal in another neural disorder, neurofibromatosis type 1; in addition, a potential mutational hot spot of NF1 at lysine at codon 1423 has been identifiedin several types of tumors. Using single-strand conformational polymorphism, we were unable to detect an abnormality in this region of NF1 in 50 samples of neuroblastoma. The data suggest that p53 mutations occasionally are associated with progression of neuroblastomas, and tumorigenetic influences of mutant p53 may differ from those of N-myc.

G-to-T transversion at codon 249 of the p53 gene has been shown to be specifically associated with human hepatocellular carcinomas, particularly that subset associated with exposure to the chemical hepatocarcinogen aflatoxin B1. We surveyed 47 North American adult hepatocellular carcinomas and three childhood liver tumors for codon 249 mutation. We report here a case of childhood hepatoblastoma in a patient, without known exposure to aflatoxin B1 or hepatitisB or C virus, whose tumor had a mutation at codon 249 involving G-to-T transversion.

Genetic and molecular abnormalities, in association with malignant phenotypes, have been previously demonstrated in a variety of human tumors. Although the multistep theory fits well for some cancers such as retinoblastoma and colon carcinoma, for many others it still remains to be proven. Neuroblastoma, a tumorfound in pediatric patients, seems to fall into the multistep model. Nonrandom chromosome abnormalities have been found with 1p deletion, loss of heterozygosity for short arm of chromosome 1 and for chromosome 11q and 14q. Amplification of N-myc oncogene and an increased level of Ras protein have also been demonstrated. Therefore, even if it is not possible to show that these mutations happen as discrete events in their order of appearance, the multistep model seems involvedin neuroblastoma development. Neuroblastoma has a peculiar aspect, however, thatmakes this tumor a natural model of defect of cell differentiation. In fact, there is a particular subset of metastatic tumors that show spontaneous regression. In vitro, neuroblastoma cell lines can be induced to differentiate along the neural pathway using retinoic acid. Other natural and chemical substances are also able to induce cell differentiation. During retinoic acid treatment, N-myc oncogene expression decreases and other genes are deregulated. p53 and MDR1 gene expression increases. These two different aspects, failure of cell differentiation pathway and genetic mutations, make the neuroblastoma one of the most difficult problems of modern molecular biology.

The Li-Fraumeni familial cancer syndrome was initially described in 1969 in a retrospective epidemiologic review of more than 600 pediatric sarcoma patients. The clinical definition of the syndrome has been refined in the last two decadesby prospective analyses of several families. Despite these exhaustive studies, the gene or genes responsible for the unusual constellation of tumors in these families remained elusive until 1990, when it was demonstrated that germline abnormalities of the p53 tumor suppressor gene could account for the occurrence of cancer in many classic Li-Fraumeni families. Identification of the molecular events that yield this phenotype has led many researchers to pursue several lines of investigation to improve our understanding of the significance of such alterations. We discuss the clinical, epidemiologic, genetic, and biologic aspects of the association between p53 and the Li-Fraumeni family cancer syndrome.

We investigated the frequency of p53 mutations in 19 pediatric cases of therapy-related leukemia or myelodysplastic syndrome. Eleven children presented with acute myeloid leukemia, one with mixed-lineage leukemia, two with acute lymphoblastic leukemia, and five with myelodysplasia at times ranging from 11 months to 9 years after a primary cancer diagnosis. The primary cancers, which included 11 solid tumors and eight leukemias, were treated with various combinations of DNA topoisomerase II inhibitors, alkylating agents, or irradiation. Leukemic or myelodysplastic marrows were screened for possible mutations by single-strand conformation polymorphism (SSCP) analysis of p53 exons 4 to 8. The only observed mutation was an inherited 2-basepair deletion at codon209 in exon 6 that would shift the open reading frame, create a premature termination codon, and foreshorten the resultant protein. Prior therapy in this patient included DNA topoisomerase II inhibitors, alkylating agents, and irradiation. The secondary leukemia presented as myelodysplasia with monosomies of chromosomes 5 and 7 and abnormalities of chromosome 17. Although the primary cancer was an embryonal rhabdomyosarcoma and there was a family history of cancer, the case did not fulfill the clinical criteria for Li-Fraumeni syndrome.This study suggests that germline p53 mutations may predispose some children to therapy-related leukemia and myelodysplasia, but that p53 mutations otherwise are infrequent in this setting.

MDM2 gene overexpression has been implicated in the pathogenesis of human neoplasia via inhibition of the p53 tumor-suppressor function. To investigate the potential involvement of the MDM2 oncogene in the pathogenesis of childhood rhabdomyosarcoma (RMS) we studied MDM2 abnormalities in six RMS cell lines in correlation with the p53 status. Three showed overexpression of MDM2 mRNA and protein, one with concomitant MDM2 gene amplification. ALL three lacked p53 mutation and expressed low levels of p53 mRNA but exhibited elevated p53 proteins. Double immunostaining revealed that the overexpressed MDM2 and p53 proteins were co-localized to the same cell nuclei. Furthermore, the two proteins were physically associated, as shown by co-immunoprecipitation and Western blot analysis. The half-life of the p53 protein was prolonged in the MDM2-expressing RMS cells. The extended half-life wildtype p53 protein and its complex formationwith the elevated MDM2 suggest that the underlying mechanism for p53 protein accumulation in these cell lines is p53 stabilization by an overabundant MDM2 protein. The overexpressed MDM2 protein had a short half-life. The three remaining RMS cell lines exhibited low MDM2 mRNA and protein levels and carried p53 mutations. This study suggest that MDM2 overexpression represents an alternative mechanism for p53 inactivation in a subset of childhood RMS without p53 mutations. The results further indicate that the elevated MDM2 protein is responsible for wildtype p53 protein accumulation via stabilization.

Consistent tumor-specific chromosomal aberrations have not been described in low-grade astrocytic tumors. The most frequent genetic alterations are mutationsof the TP53 tumor suppressor gene and/or loss of heterozygosity (LOH) on 17p that occur in about 30% of the cases in adult patients but that are uncommon in childhood tumors. We used comparative genomic hybridization (CGH) to map DNA copy number alterations in 18 primary low-grade astrocytic tumors (ten adult patientsand eight children). A gain of chromosome arm 7q was the most frequent event detected in five of ten astrocytomas (50%) from adult patients, followed by DNA amplification on chromosome arm 8q and gain on 12p (two cases). Loss of chromosomal regions on 1p, 4q, and the X chromosome was observed in two of ten cases [including one patient afflicted with Turner syndrome (45,X)]. In contrast, no consistent changes were observed in low-grade astrocytomas in children. A loss of the X chromosome was the sole aberration detected in two of eight cases usingDNA extracted from the normal brain tissue. The findings suggest that a gain of 7q is an early event in the initiation of astrocytomas in adult patients. The discrepant findings in low-grade astrocytic tumors in adults compared to tumors in children support the the hypothesis that there might be different mechanisms responsible for tumor development.

Germline mutations in the p53 tumor suppressor gene are associated with the Li-Fraumeni syndrome, characterized by childhood sarcoma, leukemia and early onset breast cancer and has occasionally been found also in familial breast-ovarian cancer. Most mutations found are of missense type and located in the central region of the gene (exons 5 to 8). In the present study, a germline p53 alteration was identified in a late onset breast cancer family (kindred Lund5; mean age 58 years) using single stranded conformation polymorphism and sequence analysis. The mutation (a CCG to CTG transition) at codon 82 in exon 4,resulting in a proline to leucine substitution, has not previously been reportedand was not present in a control set of 60 healthy individuals. Three of five woman with breast cancer (45, 57 and 65 years) were carriers of the alteration. Loss of heterozygosity at the p53 locus was not seen in the primary tumors of these women, but appeared as a partial loss of the wildtype allele in subsequentrecurrent lesions of two gene carriers. The family manifested no linkage to the p53 gene (a two-point LOD-score of -0.41), and has previously also been excludedfor linkage to the BRCA1 and BRCA2 loci, as well as being carrier of a BRCA1 germline mutation. Although it seems unlikely that the p53 germline mutation is the major cause of disease predisposition in Lund 5, the data suggest that some p53 alteration may confer a subtle influence on breast cancer development and progression.

Since the majority of germline mutations in the TP53 gene seem to occur in LFS or LFL families, and these are rare, research is best conducted in a collaborative setting (Li and Fraumeni, in press). In a report from a meeting at Bethesda in 1993, the following areas were outlined for collaborative study: the correlation(if any) of phenotypes with specific mutation; age specific penetrance; cumulative cancer incidence; gender differences in tumour development in carriers; the effects of DNA damaging agents on individuals with a TP53 mutation; the frequency of TP53 germline mutations in cohorts of patients with rare childhood tumours (eg adrenocortical carcinoma); and the psychosocial aspects ofpredictive TP53 testing. In addition, if, as seems likely from recent data, X irradiation in these individuals induces DNA damage that is tolerated, urgent collaborative studies are needed to investigate new methods of screening, such as magnetic resonance imaging. Treatment modalities should be carefully chosen, andfor this reason alone, predictive testing may be desirable in ALL LFS and LFL families. Individuals carrying TP53 mutations could be offered chemoprevention within trials in an effort to reduce their mortality from cancer.

Although primary intracranial neoplasms are the most common type of solid cancerin children, little is known about their etiology at the molecular genetic level. Recently, studies have shown that a class of genes known as tumor suppressors play an important role in the origin of several different types of human tumors,including those located in the central nervous system (CNS). Using a variety of techniques, selective loss of DNA sequences has been identified in tissue specimens from children with medulloblastoma, one of the most common pediatric brain tumors. The most consistent losses to date have been shown for probes located on distal chromosome arm 17p. Although the known tumor suppressor p53 islocated on this chromosome, and deletion and mutation of the p53 gene are the most common genetic events in human cancers of many types, such alterations havebeen infrequently detected in medulloblastoma specimens. These results suggest that inactivation of another tumor suppressor gene or genes located on 17p is important in medulloblastoma tumorigenesis. Deletion of 17p has also been shown to have implications for clinical management, as the loss of DNA sequences located on this chromosome arm is strongly associated with a negative prognosis for these patients. The identification and cloning of this tumor suppressor geneor genes will aid in understanding of the pathogenesis of medulloblastoma, as well as guiding the development of novel and more effective strategies for a cure.

Acute leukemias carrying MLL rearrangements are characterized by a high degree of clinical and immunologic heterogeneity, as demonstrated by variability in their immunophenotype, consistent with lymphoid or myeloid/monoblastic derivation, as well as their occurrence in distinct age groups from infancy to adulthood. Recently, it was shown that inactivation of the TP53 tumor suppressor gene occurs frequently in cases of acute lymphoblastic leukemia carrying MLL rearrangements.In order to assess the extent of TP53 inactivation throughout the immunophenotypic and clinical spectrum of MLL+ acute leukemias, we tested for TP53 mutations 29 cases of MLL+ acute leukemias displaying lymphoid (13 cases) or myeloid/monoblastic (16 cases) features and belonging to different age groups. mutations were detected in 6/16 myeloid/monoblastic cases and in 3/13 lymphoid cases. Among myeloid/monoblastic leukemias, the TP53 mutations occurred in 3/4 infants, but only in 3/16 cases in other age groups. Overall, our data suggest that (1) TP53 inactivation is a relatively common event in leukemias with MLL rearrangements irrespective of the leukemic phenotype and of the patients' age; (2) at least two genetic lesions (i.e., MLL rearrangement and TP53 mutation) have accumulated in the short time (few weeks after the birth or conception of the child) corresponding to the development of acute leukemias of infancy.

BACKGROUND: This article presents analysis of clinical and family data for 239 patients with childhood soft tissue sarcoma (STS) treated at the Institut Gustave Roussy in Villejuif. METHODS: A molecular study was performed to detect germlinep53 mutations in the 44 families in which at least 1 relative developed cancer before the age of 46 or in which the proband had a second neoplasm. mutations were found in five families. Standardized incidence ratio calculation and segregation analysis were used to study cancer occurrence in 4448 relatives, including first- and second-degree relatives and first cousins. RESULTS: An excess of brain tumors was observed in ALL relatives, and of breast carcinoma and STS in first-degree relatives of patients with STS. An excess of breast carcinoma was observed only in young mothers of patients with rhabdomyosarcoma. This excess might be mostly linked to the presence of a germline p53 mutation because it wasno more significant when excluding families in which such a mutation existed. Noassociation between breast carcinoma in the mother and rhabdomyosarcoma of the genitourinary tract in the proband was observed. This should be kept in mind when developing a screening strategy for breast carcinoma in mothers of patients withSTS. Segregation analysis showed evidence for transmission of an autosomal dominant gene with complete penetrance by the age of 84. The genetic component was explained primarily by p53 germline mutations. CONCLUSIONS: These results show that most relatives of patients with STS are at the same risk for cancer asthe general population.

This report describes an unusual clinical presentation of Li-Fraumeni syndrome. Family history revealed a mild aggregation of adult cancers in one generation, and an unusual clustering of brain tumours of early childhood in the following generation. In order to evaluate the genetic basis for cancer predisposition in this family, molecular genetic analysis for the occurrence of germline TP53 tumour suppressor gene mutations was performed on 12 siblings of two generations. Indirect mutation analysis was performed by the single-strand conformation polymorphism (SSCP) technique. Alterations were characterised by automated direct fluorescence sequencing analysis. tumour material was also examined for p53 protein accumulation by immunohistochemistry. Initially, a TP53 gene germline missense mutation was detected in an 11-year-old kindred with acute myeloid leukaemia (AML) following intensive treatment of a brain tumour. In peripheral blood and bone marrow samples of this proband, a reduction to hemizygosity occurred. During AML treatment, detection of LOH of 17p was used as a marker forclonality and treatment control. The mutation was found to be inherited from theproband's mother, who was diagnosed with breast cancer at the age of 48 years. Further, three siblings were carriers, and two are apparently healthy at the ageof 21 and 23 years. Knowledge of germline mutations may allow accurate DNA-basedcarrier diagnosis which is of important clinical significance for treatment strategy and control. Furthermore, the occurrence of unaffected carriers in thisfamily raises questions about appropriate methods of cancer surveillance and counselling for these people.

Two different processes appear to be involved in the initiation of hepatocarcinogenesis by chronic hepatitis B virus (HBV) infection and by chronichepatitis C virus (HCV) infection. Initiation of hepatocellular carcinoma (HCC) by chronic HBV infection usually occurs early in life; most patients have had onset of HBV infection before the end of childhood, although rare cases of HCC have been reported following HBV infections acquired in adulthood. In contrast, HCV-associated HCC in many cases probably develops after a chronic HCV infectionthat was acquired during adulthood. HBV-DNA usually is integrated in the tumor DNA of HBV-associated HCC; it produces two proteins that can transactivate knownoncogenes in vitro and that theoretically could affect genes at distant sites invivo. HCV is a nonintegrating virus and no transactivating HCV proteins have been identified so far. In the later stages of hepatocarcinogenesis, "tumor promotion" and "tumor progression," HBV-associated HCC may share certain features with those of HCV-associated HCC. Chronic inflammation and cirrhosis, accompanied by regenerative processes, may function as a tumor promoter, providing a common pathway from chronic HBV or HCV infection to HCC. tumor progression may be brought about in HCC by mutations of the p53 tumor suppressor gene. mutations ofthis gene are common in HCCs, and they are found more often in advanced human HCCs than in small, well-differentiated HCCs. The prevalences of p53 mutations are similar in HBV-associated and HCV-associated HCCs (30-50%). Even in the absence of a p53 mutation, the functions of normal p53 can be inactivated as a result of binding by viral or by cellular proteins. It is not known yet whether this type of binding contributes to the development of HCC, but p53 binding by the HBV X protein in vitro has been reported. Abnormalities of the RB tumor suppressor gene also have been found frequently in HCC patients, particularly inHCCs that contain p53 mutations.

Eight histologically-confirmed cases of clear cell sarcoma of the kidney (CCSK) were studied for possible mutations in the p53 tumor suppressor gene by the immunohistochemical demonstration of mutant p53 proteins using a monoclonal (DO7: Dako) and a polyclonal (AB565: Chemicon) antibody to p53 protein. ALL cases exhibited p53 protein nuclear immunopositivity, although in varying numbers of tumor cells and with different staining intensities. p53 protein (DO7 or AB565) was expressed in < 25% of the tumor cells in four (50%) of the cases, including the one case with a known long term survival of 13 years from the time of diagnosis. The other tumors showed p53 protein immunopositivity in > 25% of the tumor cells when stained with either DO7 or AB565 or both. The intensity of staining, graded on visual impression into weak, moderate or strong, did not correlate well with the ratio of positive staining tumor cells. While this studyis unable to clarify the relative prevalence and importance of p53 mutational events in the pathogenesis of this aggressive renal tumor of childhood, it is reasonably suggestive that alterations in the p53 tumor suppressor gene do occurin CCSK.

tumor DNA from 45 primary basal cell carcinoma (BCC) biopsies was screened for p53 gene mutations, chromosome 9 allele loss, and microsatellite instability. p53 mutation frequency increased significantly as a function of the age at BCC onsetranging from 6% (1/16) in early BCC (before age 40 years) to 35% (10/29) in lateBCC. ALL p53 mutations found implicated sunlight as the mutagen. Chromosome 9 instability (allele loss or microsatellite instability) was detected at high frequency (38%) independently of age at tumor onset. Allelic loss was confined to chromosome 9q, whereas microsatellite instability was observed prevalently on chromosome 9p often in association with a replication error (RER+) phenotype. Most of our late BCC patients reported occupational sun exposure, while early BCC patients recalled childhood (0-20 years) recreational sun exposure. These data suggest that chronic exposure to sunlight is responsible for accumulation of p53mutations and thus for late BCC appearance, whereas acute UV exposure in childhood and adolescence leads to early skin cancer development in genetically susceptible individuals via a p53-independent pathway.

Screening for p53 mutations in exons 5 to 8 in 124 pediatric malignancies identified 18 abnormal shifts using single strand conformation polymorphism: 12 were missense mutations and in 6, no mutation was detected in the exon or in thesplice donor acceptor sequences. Sequencing was then performed in the adjacent introns, revealing a G to A base substitution at 39 base pairs upstream to exon 7. This mutation was identified in the germ line of five of the patients, and also in the father of one, whose parents were available. For comparison, of the 184 normal controls similarly screened, only one had this mutation (P=0.036). Positive staining of p53 protein was observed in three of the paraffin embedded tissues that were available: brain tumor, rhabdomyosarcoma, and lymphocytes froma normal lymph node from the rhabdomyosarcoma patient. ALL tumors with the identified intron mutation were Li-Fraumeni syndrome tumors. Sequencing of ALL exons including splice sites was performed and revealed no mutation. We suggest that this mutation in intron 6 of the p53 gene stabilizes the wild type p53 protein, resulting in its abnormal accumulation. mutations in the noncoding region of p53 should be further studied.

Screening for p53 mutations in exons 5 to 8 in 124 pediatric malignancies identified 18 abnormal shifts using single strand conformation polymorphism: 12 were missense mutations and in 6, no mutation was detected in the exon or in thesplice donor acceptor sequences. Sequencing was then performed in the adjacent introns, revealing a G to A base substitution at 39 base pairs upstream to exon 7. This mutation was identified in the germ line of five of the patients, and also in the father of one, whose parents were available. For comparison, of the 184 normal controls similarly screened, only one had this mutation (P=0.036). Positive staining of p53 protein was observed in three of the paraffin embedded tissues that were available: brain tumor, rhabdomyosarcoma, and lymphocytes froma normal lymph node from the rhabdomyosarcoma patient. ALL tumors with the identified intron mutation were Li-Fraumeni syndrome tumors. Sequencing of ALL exons including splice sites was performed and revealed no mutation. We suggest that this mutation in intron 6 of the p53 gene stabilizes the wild type p53 protein, resulting in its abnormal accumulation. mutations in the noncoding region of p53 should be further studied.

Detection of p53 protein expression and overexpression has been reported to be associated with poor prognosis in a number of human malignancies. The aim of this study was to utilize immunocytochemical antigen detection techniques to search for evidence of abnormal p53 protein accumulation in ten human childhood astrocytoma (ASTR) subtypes (five pilocytic, two pure anaplastic, one anaplasticASTR with primitive neuroectodermal tumor elements, one ASTR containing a majority of oligodendrocytes and one glioblastoma multiforme). The immunocytochemistry was carried out on routine, formalin fixed, paraffin-wax embedded 3 to 4 microns thick ASTR tissue sections. A four step, indirect, biotin-streptavidin based method was employed with peroxidase enzyme conjugation. Surprisingly, p53 protein expression was demonstrated in ALL ten ASTRs. The immunoreactivity pattern was mostly heterogeneous, with cells groups of similar intensity clustered within the ASTRs. The number of cells stained and the intensity of the immunoreactivity correlated directly with the known degree of malignancy of the various subtypes of ASTRs: lowest in the pilocytic ASTR cases and highest in the glioblastoma multiforme. Low-grade human ASTRs possess an intrinsic tendency for cell dedifferentiation toward the embryonic cell immunophenotype (IP). Loss of p53 function is associated with most, if not all, human malignancies. mutation of p53 has yet to be demonstrated in pilocytic ASTRs. The accumulation of p53 in some pilocytic ASTR cells, as demonstrated in our study, suggests that the mere dysfunction of the p53 protein may be involvedin the ealry stages of ASTR progression from the grade I pilocytic subtype to the more "malignant" pure ASTR, which is characterized by p53 gene mutations. The loss of p53 provides the necessary genetic instability needed for further IP changes and further progression towards more malignant IPs, e.g. anaplastic ASTRand glioblastoma multiforme. Such facts make the use of p53 in the assessment ofASTRs indispensible. p53 levels may be used in identifying cell clones within pilocytic ASTR microenvironments, which have a clear tendency for progression toward more malignant IPs and the establishment of the alteration of the p53 gene in more advanced ASTR subtypes (grades II to IV).

The etiopathogenesis of neoplastic diseases is characterized by its multiple nature. Multiple biological and physical agents have been identified as initiating or promoting neoplastic mechanisms. However, they ALL appear to have common molecular basis, granting genetic instability and causing somatic derangements to preneoplastic and tumor cells. Target genes implicated in cellular transformation and tumor progression have been divided into two categories: proto-oncogenes (that when activated become dominant events characterized by gain of function) and tumor suppressor genes (recessive events characterized by the loss of function). Alteration in proto-oncogenes and tumor suppressor genes seem equally prevalent among human cancers. Multiple mutations appear to be required to conform the malignant phenotype. It is, therefore, conceivable to view cancer as fundamentally a genetic disease entailing inherited (also called "germline") or acquired (also termed "somatic") mutations of genes in these two categories. The concept of tumor suppressor genes was established in studies with somatic cell hybrids, revealing that when malignant cells were fused with normal cells some of the hybrids were nontumorigenic. Clinically, the existence and relevance of this category of genes was based on epidemiological studies of the intraocular childhood tumor retinoblastoma, and it was postulatedthat two independent events were needed to inactivate a given gene. It was further shown that, in general, that was achieved by an allelic loss followed bya point mutation of the remaining allele. A family of genes has been characterized that follows this "two-hit" model including the two prototype suppressors genes: the retinoblastoma (RB) and the TP53 (also known as p53) genes. These genes encode a variety of molecules with distinct biological properties, including cell cycle regulation and cellular differentiation. Germline and somatic mutations of these genes appear to be the most common abnormalities found in human cancer including bladder neoplasms. More recent studies have shown that inactivation of some of these genes (i.e., TP53) occurs in bladder tumors that have a more aggressive clinical outcome and poor prognosis. In the following subheadings, the authors have reviewed the molecularabnormalities associated with these recessive genes in bladder tumors and discuss the potential clinical use of their detection. The implementation of objective predictive assays to identify these alterations in clinical material will enhance the ability to assess tumor biological activities and to design effective treatment regimens. The need now is to translate this newly developed scientificknowledge into diagnostic and therapeutic strategies, which, in turn, will enhance quality of life and prolong patient survival.

Glioblastoma multiforme is a rare neoplasm in children and is often located infratentorially, particularly in the brainstem: pediatric glioblastomas arise frequently (here 60%) outside the cerebral hemispheres. We investigated 20 pediatric glioblastomas for mutational inactivation of the p53 tumor suppressor gene, loss of p16 protein expression and overexpression of the epidermal growth factor receptor (EGFR). mutations in the p53 gene were identified in 5/20 (25%) glioblastomas, 4 of which occurred in primary glioblastomas with a clinical history of less than 4 months and neither clinical nor histologic evidence of a less malignant precursor lesion. Loss of p16 expression was detected in 11/18 (61%) glioblastomas. Overexpression of the EGFR was infrequent (2/19, 11%) and included 1 tumor with a p53 mutation. Of 4 secondary glioblastomas that progressed from histologically diagnosed lower grade tumors, one contained a p53mutation. Our results are at variance with similar studies in adult patients in which primary and secondary glioblastomas are characterized by EGFR overexpression and p53 mutations, respectively, suggesting that the evolution ofpediatric glioblastomas follows different genetic pathways.

The MYCN oncogene is amplified in 20% of childhood neuroblastoma and is associated independently with poor prognosis. Alteration of the p53 tumor supressor gene, in contrast, occurs infrequently in these tumors. In this report, we described a 3-year-old girl with stage IV neuroblastoma. Molecular analysis revealed, both MYCN gene amplification and a point mutation of the p53 tumor supressor gene. To our knowledge, this is the first reported case of neuroblastoma with genetic alterations of both these genes.

Recent data suggest that deletion of p16INK4 and mutation of TP53 are among the most common genetic events in the development of human cancer, since the codified proteins act as brakes of the abnormal cell cycle. As the molecular events leading to the development of pediatric bone sarcomas remain unclear, we analyzed 75 osteosarcoma and Ewing sarcoma samples from 43 pediatric patients to search for alterations at the TP53 or p16INK4 tumor suppressor genes. By means of PCR-DGGE (polymerase chain reaction and denaturing gradient gel electrophoresis)we detected TP53 point mutations in 18.6% of the tumor samples, but no constitutional mutations. In the analysis of p16INK4, 7% of the samples harboreddeletions of the gene but no point mutations were detected by SSCP (single strand conformation polymorphism) analysis, just the polymorphism Ala-->Thr at codon 148. These data support the hypothesis that TP53 alterations may play a role in the development of pediatric bone tumors and that the primary mechanism of inactivation of p16INK4 seems to be homozygous deletion rather than point mutation.

The PTEN gene, located on 10q23, has recently been implicated as a candidate tumor suppressor gene in brain, breast and prostate tumors. In the present study, 123 brain tumors, including various grades and histological types of gliomas occurring in children and adults, were analyzed for PTEN mutations by SSCP assayand sequencing. mutations in the PTEN gene were found in 13 of 42 adult glioblastomas and 3 of 13 adult anaplastic astrocytomas, whereas none of the 21 low-grade adult gliomas or the 22 childhood gliomas of ALL grades showed mutations. The single medulloblastoma with a mutation was a recurrent tumor thatalso possessed a p53 mutation. High-grade adult gliomas with PTEN mutations included cases that also contained gene amplification or p53 gene mutations, as well as cases that did not contain either of these abnormalities. There was no obvious relationship between presence of PTEN mutation and survival; however, there was a tendency for PTEN mutations to occur in older age group patients. This analysis suggest that PTEN gene mutations are restricted to high-grade adult gliomas and that this abnormality is independent of the presence or absence of gene amplification or p53 gene mutation in these tumors.

bcl-2 protein expression was characterized in a series of 58 astrocytomas from 21 pediatric and 37 adult patients. As part of a continuing attempt to define relevant prognostic factors which may predict clinical outcome, we have determined the impact of bcl-2 accumulation in malignant astrocytes on the length of patient survival. Aberrant overexpression of bcl-2 protein in tumor cells wasdetected in 57% (12 of 21) of pediatric and 73% (27 of 37) of the adult cases. Among pediatric patients, the median survival in months showed no relationship with the incidence of bcl-2-positive tumors. Among the adult patients, a favorable prognostic indicator was low-tumor grade (P = 0.05). bcl-2-positive tumors occurred with similar frequencies in WHO grades III and IV of malignancy.When bcl-2 expression in tumor cells was tested as a variable to predict for patient survival, the 6 patients without bcl-2 expression among 23 adult patients with grade IV tumors had a shorter median survival. The same 58 tumors had been previously analyzed for alterations of p53:4 pediatric and 16 adult tumors had p53 gene mutations. There was no significant difference in median survival related to p53 gene status. There was no relationship between bcl-2 expression and p53 gene status: approximately equal numbers of tumors with either wild-typeor mutant p53 were bcl-2 negative or bcl-2 positive. bcl-2 expression is high (40-100%) among other tumors of the central nervous system which also show low malignant potential. Up-regulation of bcl-2 in malignant astrocytes or constitutive expression in some tumor types may be a factor leading to a more favorable clinical outcome.

Retinoblastoma is an intraocular malignancy of childhood, which is very radiosensitive. gamma-irradiation, however, induces side effects, and the precise mechanisms of tumor cell death after the treatment remain unknown. In this study, we demonstrated that gamma-irradiation induced apoptosis (programmed cell death)in human retinoblastoma cell lines Y79 and WERI-Rb-1. The expression levels of p53, tumor suppressor gene product, and its-associated protein, WAF1/CIP1, were both up-regulated, and function of p53 was remarkably activated after the treatment. Moreover, apoptosis was induced in the absence of gamma-irradiation by overexpression of the WAF1/CIP1 gene in both retinoblastoma cells. These resultsindicate that the transfer of the WAF1/CIP1 gene may have potential for the treatment of human retinoblastomas instead of gamma-irradiation.

BACKGROUND/AIMS: Abnormalities of the p53 gene can lead to the production of anti-p53 antibody in the serum of cancer patients. We evaluated the prognostic significance of anti-p53 antibody in 86 patients with hepatocellular carcinoma (HCC) in comparison with clinicopathological factors: age, sex, etiology, smoking and drinking habits, history of blood transfusion, presence of encephalopathy and ascites, child classification, Pugh score, bilirubin, albumin, prothrombin time,indocyanine green retention time at 15 min (ICG), underlying liver disease, alpha-fetoprotein (AFP), tumor size, number of tumors, differentiation degree ofHCC, presence of extrahepatic metastasis and therapy for HCC. METHODS: The serumanti-p53 antibody in 86 patients with HCC, 20 with chronic hepatitis (CH) and 20with liver cirrhosis (LC) was measured by an enzyme-linked immunosorbent assay (ELISA). A single-strand conformation polymorphism-polymerase chain reaction (SSCP-PCR) analysis and loss of heterozygosity (LOH) study of the p53 gene were performed using 8 tissue samples of 8 HCC from four antibody-positive and four antibody-negative patients. The survival probabilities were assessed by the Kaplan-Meier technique, and a Cox regression analysis was used to identify the independent factors for prognosis. RESULTS: Anti-p53 antibody was positive in 32% (28 of 86) of the sera from patients with HCC, but in none of the 20 with CH and20 with LC. p53 antibody positivity was associated with bilirubin and the numberof tumors (p=0.027 and p=0.018, respectively). Overall survival was shorter in the HCC patients with p53 antibody than in those without p53 antibody (p<0.02). Bilirubin, p53 antibody, AFP and ICG were found to be significant prognostic factors by univariate analysis. A Cox multivariate analysis showed that bilirubin and p53 antibody were independent prognostic variables (p<0.0001 and p=0.003, respectively). In four antibody-positive patients, mutation and LOH of the p53 gene were detected in one patient and two patients, respectively. In contrast, only one of four antibody-negative patients exhibited LOH of the p53 gene. CONCLUSIONS: Serum anti-p53 antibody could be a useful prognostic factor in patients with HCC.

BACKGROUND: Young patients with neurofibromatosis type 1 (NF1) are at increased risk of developing various malignancies, most of which are myeloid disorders. The observed loss of NF1 allele in the myeloid malignancies of NF1 patients suggestsa role of NF1 as a tumor suppressor gene. Loss of 17p was found to be quite frequent in neural crest tumors from patients with NF1, raising the possibility of p53 tumor suppressor gene involvement in other NF1-related tumors. METHODS: The authors studied mutations in the NF1 and p53 genes, using loss of heterozygosity, single strand conformation polymorphism, heteroduplex and sequencing analyses. RESULTS: An NF1 germline mutation was identified in exon 31of a child who developed juvenile chronic myelogenous leukemia (JCML). The mutation was segregated within the proband's family. A 14bp deletion at exon 6 of the p53 gene was observed when JCML was diagnosed, and the wild-type p53 allele was lost during progression of the disease. No loss of the normal NF1 allele could be detected. CONCLUSIONS: A germline mutation in the NF1 gene and sequential inactivation of p53 alleles in the malignant clone of JCML raise the possibility of a correlation between NF1 and p53 genes in the tumorigenesis of JCML.

BACKGROUND: Young patients with neurofibromatosis type 1 (NF1) are at increased risk of developing various malignancies, most of which are myeloid disorders. The observed loss of NF1 allele in the myeloid malignancies of NF1 patients suggestsa role of NF1 as a tumor suppressor gene. Loss of 17p was found to be quite frequent in neural crest tumors from patients with NF1, raising the possibility of p53 tumor suppressor gene involvement in other NF1-related tumors. METHODS: The authors studied mutations in the NF1 and p53 genes, using loss of heterozygosity, single strand conformation polymorphism, heteroduplex and sequencing analyses. RESULTS: An NF1 germline mutation was identified in exon 31of a child who developed juvenile chronic myelogenous leukemia (JCML). The mutation was segregated within the proband's family. A 14bp deletion at exon 6 of the p53 gene was observed when JCML was diagnosed, and the wild-type p53 allele was lost during progression of the disease. No loss of the normal NF1 allele could be detected. CONCLUSIONS: A germline mutation in the NF1 gene and sequential inactivation of p53 alleles in the malignant clone of JCML raise the possibility of a correlation between NF1 and p53 genes in the tumorigenesis of JCML.

mutations in the p53 tumour-suppressor gene (exons 5-8) were investigated in 31 Belarussian childhood thyroid tumours (24 cases of papillary thyroid carcinoma, 3 benign tumours and 2 cases each of thyroiditis and goiter); 33 thyroid tumours from juveniles and adults without radiation exposures (25 carcinomas of various histological types, including 11 papillary carcinomas and 8 adenomas) and 6 tumours from adults (4 papillary carcinomas, 1 adenoma, 1 goiter) served as controls. The mutational spectrum of p53 differed greatly between the childhood thyroid carcinomas from Belarus and the control groups. In the control groups of29 malignant thyroid tumours, 7 different mutations were detected on exons 5-8, none of which occurred among the 15 papillary carcinomas in this group. Five mutations were found in tissue samples of the 24 childhood papillary carcinomas,and they were ALL the same p53 point mutation (CGA --> CGG) on codon 213 of exon6. To determine whether this mutation is simply a polymorphism or whether it is specific to the tumour cells, laser-assisted microdissection was applied to collect various areas of tumorous and non-tumorous cells (10-20 cells per sample) from each paraffin-embedded tissue section of 8 of the papillary thyroid carcinomas. Using PCR-SSCP and sequence analysis on these cells, the very same p53 mutation on codon 213 was detected in various microdissected tumour samples of 2 cases, but it was not found in any microdissected non-tumorous sample. The exclusive occurrence of this p53 mutation in selective microdissected samples oftumour cells, even as homozygous mutation in 1 case, reflects a distinct tumour heterogeneity within papillary childhood thyroid carcinomas.

PURPOSE: pediatric central nervous system (CNS) tumors comprise a wide variety of histologic subtypes ranging from the benign juvenile pilocytic astrocytoma to the highly aggressive atypical teratoid/rhabdoid tumor. Although some brain tumors are seen in association with inherited genetic disorders which predispose to malignancies, most are sporadic. Current knowledge regarding the cytogenetic andmolecular genetic events which have been implicated in the development or progression of common brain tumors in children in the subject of this review. METHODS: Combined cytogenetic and molecular genetic approaches, including fluorescence in situ hybridization, have been used to identify genomic alterations in different histologic types of pediatric brain tumors. RESULTS: The most frequent abnormality in primitive neuroectodermal tumor/medulloblastoma is an i(17q), present in approximately 50% of cases. This finding implicates the presence of a tumor suppressor gene on 17p, which is important in tumor development. A number of genes on 17p have been eliminated as candidates for this locus, including TP53. A tumor suppressor gene in chromosome band 22q11.2 has been hypothesized to play a role in atypical teratoid/rhabdoid tumors, and positional cloning strategies are in progress to identify a rhabdoid tumor gene.Chromosome 22 deletions are also seen in meningiomas and a small percentage of ependymomas, but it is not yet known whether the same gene is responsible for more than one malignancy. With regard to childhood astrocytomas, tumor-associated genetic changes have not yet been identified for the common juvenile pilocytic or low grade diffuse astrocytoma. In contrast, malignant anaplastic astrocytomas and glioblastoma multiforme have abnormalities similar to those seen in adults, including loss of alleles on 17p13 and TP53 mutations, trisomy 7, EGFR rearrangements, and loss of chromosomes 10 and 22. CONCLUSIONS: The presence of tumor-associated genetic abnormalities has clinical utility in a differential diagnostic setting, and has lead to the identification of genes which contributeto tumorigenesis.

We describe two Li-Fraumeni syndrome families. Family A was remarkable for two early childhood cases of adrenocortical tumours, family B for a high incidence of many characteristic cancers, including a childhood case of choroid plexus tumour. Using direct sequencing, we analysed exons 5-9 of the p53 gene in constitutionalDNA of individuals from both families and found two novel germline mutations in exon 5. In family A, we detected a point substitution in codon 138 (GCC to CCC),which resulted in the replacement of the alanine by a proline residue. Family B harboured a single-base pair deletion in codon 178 (CAC to -AC), resulting in a frameshift and premature chain termination. Three out of six tumours examined from both families, a renal cell carcinoma, a rhabdomyosarcoma and a breast cancer, showed loss of heterozygosity and contained only the mutant p53 allele. The remaining three neoplasms, both adrenocortical tumours and the choroid plexus tumour retained heterozygosity. Immunohistochemistry with anti-p53 antibody confirmed accumulation of p53 protein in tumours with loss of heterozygosity, while the remaining tumours were p53 negative. These results support the view that complete loss of activity of the wild-type p53 need not be the initial event in the formation of ALL tumours in Li-Fraumeni individuals.

WT1 encodes a tumor suppressor that is expressed in cells of the developing kidney and is inactivated in Wilms tumor, a pediatric kidney cancer. The adenovirus E1B 55K gene product contributes to the transformation of primary baby rat kidney (BRK) cells by binding and inactivating the product of the p53 tumor suppressor. We have previously demonstrated that WT1 and p53 are present within a protein complex in vivo. We now show that WT1 is physically associated with E1B 55K in adenovirus-transformed cells, an interaction that is mediated by the first two zinc fingers of WT1. Immunodepletion of p53 abrogates the coimmunoprecipitation of E1B 55K and WT1, consistent with the presence of a trimeric protein complex containing these three proteins. In the presence of E1B55K, WT1 which is normally localized in the nucleus, is retained within a very high molecular weight complex and sequestered in the characteristic perinuclear cytoplasmic body that contains E1B 55K and p53. expression of E1B 55K in osteosarcoma cells that undergo apoptosis following expression of WT1 inhibits WT1-mediated cell death. We conclude that E1B 55K may target WT1 along with p53,resulting in the functional inactivation of both tumor suppressor gene products by this viral oncoprotein.

OBJECTIVE: Alterations affecting tumor suppressor genes, specifically p16INK4 and TP53, have been shown to be involved in the development of human cancer due to their important role in the control of normal cell cycle progression. As the genetic events leading to the development of pediatric osteosarcoma remain partially unclear, we have tested the possibility that a significant number of pediatric osteosarcoma patients harbor mutations in these genes. PATIENTS AND METHODS: We have analyzed 64 samples (fresh tissues, paraffin embedded biopsies and peripheral blood lymphocytes) corresponding to 38 pediatric osteosarcoma patients. TP53 mutations were analyzed by DGGE (Denaturing Gradient Gel Electrophoresis) analysis of exons 5 through 8. We searched for deletions in thep16INK4 gene by PCR (Polymerase Chain Reaction) analysis and point mutations were screened by means of SSCP (Single Strand Conformation Polymorphisms). RESULTS: Our analysis showed that 18.4% of the samples harbored mutations in the coding region of TP53 and that 7% had a homozygous deletion of the p16INK4 gene. Our results suggest that p16INK4 deletions may constitute a bad prognostic factor and that TP53 alterations may be correlated, although not statistically, with reduced survival time. CONCLUSIONS: mutations of the TP53 and deletion of p16INK4 tumor suppressor genes seem to be involved in the development of pediatric osteosarcoma. Moreover, alterations of these genes may constitute a prognostic factor related with poor prognosis or decreased survival time.

The role of tumor suppressor genes and oncogenes in the development of Ewing's sarcoma has not yet been fully clarified. In this study, we analyzed the frequency of p53 tumor suppressor gene mutation in exons 4-8 by PCR-SSCP and direct sequencing, and the expression of p53-protein in Ewing's sarcoma (ES) by using immunohistochemistry. The overexpression of MDM2, which acts as a functional inactivator of p53, was studied by immunohistochemistry. In addition,a screening for point mutations in the hot spot regions codon 12 and 13 of exon 1 and codon 61 of exon 2 of ras-genes (H-ras, N-ras, K-ras) was performed. In one case, a p53 gene mutation could be confirmed in codon 238 of exon 7 (1/24). Overexpression of MDM2 was found in five cases; in ras-genes, no mutations were detected. Compared with other highly malignant mesenchymal pediatric tumors suchas osteosarcomas, mutations of p53 and ras in Ewing's sarcomas are an extraordinarily rare event. However, their frequency is comparable to that of PNET, suggesting that the low incidence of these mutations in ES and PNET could be group-specific for tumors of neuroectodermal genesis.

We identified a novel germ-line p53 mutation in the noncoding, nonsplicing regions of a Li-Fraumeni family. Patients belonging to this family included pediatric medulloblastoma and rhabdomyosarcoma patients and a breast carcinoma patient. Three positions in the p53 gene were analyzed for loss of heterozygosity (LOH). One of the three loci retained heterozygosity, whereas the other two exhibited LOH. Sequence analysis of the third locus identified a change of 5'-CCGGGTGA-3' to 5'-CCAGGTTGGA-3', 63 bp downstream of exon 6. The mutation wasidentified in the germ line of the two pediatric patients and in each of the related parents. We excluded any additional mutation in the entire coding regionof the p53 gene, including splice-site intronic sequences. Strong positive nuclear staining of the p53 protein was detected in both normal and tumor paraffin-embedded tissues. Eighty-five normal persons were negative for this alteration, which thus supports it as a mutation. These results may indicate that genetic changes within the noncoding region of the p53 gene may serve as an alternative mechanism of activating this gene. mutations in the noncoding regionof this gene should be further studied.

We identified a novel germ-line p53 mutation in the noncoding, nonsplicing regions of a Li-Fraumeni family. Patients belonging to this family included pediatric medulloblastoma and rhabdomyosarcoma patients and a breast carcinoma patient. Three positions in the p53 gene were analyzed for loss of heterozygosity (LOH). One of the three loci retained heterozygosity, whereas the other two exhibited LOH. Sequence analysis of the third locus identified a change of 5'-CCGGGTGA-3' to 5'-CCAGGTTGGA-3', 63 bp downstream of exon 6. The mutation wasidentified in the germ line of the two pediatric patients and in each of the related parents. We excluded any additional mutation in the entire coding regionof the p53 gene, including splice-site intronic sequences. Strong positive nuclear staining of the p53 protein was detected in both normal and tumor paraffin-embedded tissues. Eighty-five normal persons were negative for this alteration, which thus supports it as a mutation. These results may indicate that genetic changes within the noncoding region of the p53 gene may serve as an alternative mechanism of activating this gene. mutations in the noncoding regionof this gene should be further studied.

The predisposition to malignancy that is dominantly inherited in Li-Fraumeni syndrome is associated with germline mutations of the tumour suppressor gene p53. Although second malignant neoplasms have been described in children with p53 mutations, the synchronous occurrence of two embryologically different tumours in these children has not been reported. A 20 month old girl with failure to thriveand congenital heart defects was found to have unilateral adrenal masses which, at surgical removal, proved to be an adrenocortical carcinoma and a ganglioneuroblastoma. Further investigation showed a germline p53 mutation and Turner syndrome. It remains to be determined what effect the 45,X chromosomal complement may have on the expression of neoplasms seen in patients with p53 germline mutations.

Segmental jumping translocations are chromosomal abnormalities in treatment-related leukemias characterized by multiple copies of the ABL and/or MLL oncogenes dispersed throughout the genome and extrachromosomally. Because gene amplification potential accompanies loss of wild-type p53, we examined the p53 gene in a case of treatment-related acute myeloid leukemia (t-AML) with MLL segmental jumping translocation. The child was diagnosed with ganglioneuroma andembryonal rhabdomyosarcoma (ERMS) at 2 years of age. Therapy for ERMS included alkylating agents, DNA topoisomerase I and DNA topoisomerase II inhibitors, and local radiation. t-AML was diagnosed at 4 years of age. The complex karyotype ofthe t-AML showed structural and numerical abnormalities. Fluorescence in situ hybridization analysis showed multiple copies of the MLL gene, consistent with segmental jumping translocation. A genomic region including CD3, MLL, and a segment of band 11q24 was unrearranged and amplified by Southern blot analysis. There was no family history of a cancer predisposing syndrome, but single-strandconformation polymorphism (SSCP) analysis detected identical band shifts in the leukemia, ganglioneuroma, ERMS, and normal tissues, consistent with a germline p53 mutation, and there was loss of heterozygosity in the ERMS and the t-AML. Sequencing showed a CGA-->TGA nonsense mutation at codon 306 in exon 8. The results of this analysis indicate that loss of wild-type p53 may be associated with genomic instability after DNA-damaging chemotherapy and radiation, manifestas a complex karyotype and gene amplification in some cases of t-AML.

A search of TP53 mutations was undertaken in a series of 51 pediatric brain tumors. The only germ-line mutation was detected in a 9-year-old girl with a PNET. Her family history was unremarkable for neoplastic disease, except for thepaternal grandfather, who died of a gallbladder carcinoma at an advanced age. The mutation was a thymine deletion at the first base of codon 241, leading to termination codon at position 246 that has not previously been reported. This mutation was found to be inherited from the proband's father, who was healthy atage 40. In the tumoral sample, loss of heterozygosity in several 17p markers wasfound, the only TP53 allele preserved in the tumor was the mutated one. The presence of two short tandem repeats and two different palindromic sequences spanning the deletion lead us to propose the predisposition of this region to forming a complex secondary structure during replication. Consequently, it couldhave facilitated the present deletion. Furthermore, six other short deletions affecting--partially or totally--the region implicated in the folding model thatwe propose have been described in the literature. These findings confirm that this sequence represents a hotspot of deletion in the TP53 gene.

The p53 tumor supressor gene is the most frequently mutated gene in human cancers. Approximately 40% of astrocytic tumors have alterations of the p53 gene, which are considered to play an important role in tumorigenicity and malignant progression. Since the main functions of normal p53 are cell-cycle regulation and induction of apoptosis, p53 mutations are considered to be associated with rapidtumor growth and resistance to radiation and chemotherapy. Although in certain cancers, p53 mutations are considered a poor prognostic factor, the predictive role in astrocytic tumors is not clear. Immunohistochemical studies have shown conflicting results, probably because this technique fails to provide a reliablep53 gene status. mutation analyses have shown the association between p53 mutations and shorter survival of high-grade gliomas only in pediatric patients,but not in adults. This may suggest that p53 mutations have a relatively lower impact on the survival of malignant astrocytomas than other gene alterations, which pediatric tumors rarely harbor.

Fas (APO-1/CD95) is a cell-surface protein that can mediate apoptosis upon specific ligand or antibody binding. The Bcl-2 protein may function as a modulator of Fas-induced apoptosis by blocking a downstream activation step, andBcl-2 expression in acute lymphoblastic leukemia (ALL) cells appears to depend partly on expression of a wild-type (wt) p53 tumor suppressor gene (Findley et al, Blood 1997; 89: 2986). We therefore investigated the relationship between sensitivity to Fas-mediated apoptosis and (1) Fas expression, (2) p53 status, and (3) Bcl-2 protein levels in pediatric ALL cell lines and primary leukemic cells.Cell lines included 21 B cell precursor (BCP)-ALL and four T-ALL lines; in five cases, cryopreserved primary leukemic cells from which these lines were established were also examined. Additionally, we evaluated the effect of anti-Fas monoclonal antibody on the activation of protease CPP32 and induction of apoptosis in these lines. By SSCP analysis and DNA sequencing, we detected p53 mutations (mt) in eight out of 25 ALL cell lines (exon-7, codon 248 n=6; exon-8,codon 273, n=2). The expression of Fas and Bcl-2 was examined by immunofluorescence staining and quantified as the number of molecules of equivalent soluble fluorochrome (MESF). Elevated levels of Fas were expressed inall six lines with a mutation of p53 in codon 248 (1500 to 10800 MESF). AlthoughFas was detectable in seven of the 17 lines with wt-p53, expression was lower (150-900 MESF) compared with mt-p53+ lines. Bcl-2 was expressed in 10 of the 25 lines. Most (9/10) wt-p53+ lines expressed Bcl-2, whereas only one of eight mt-p53+ lines and no p53-null lines expressed this protein. Treatment of Fas-positive lines with anti-Fas monoclonal antibody (200 ng/ml) for 6 h inducedactivation of CPP32 and apoptosis in eight of 13 Fas+ lines. Sensitivity to Fas-mediated apoptosis was associated with a mt-p53 phenotype and absence of Bcl-2 expression. Six of eight Fas+/Fas-sensitive (S) lines were mt-53+/Bcl-2-, whereas only two Fas+/Fas-S lines were wt-p53+/Bcl-2+; both of these latter lines expressed low levels of Bcl-2 compared to Fas-resistant lines. In contrast, fourof five Fas+/Fas-resistant (R) lines were wt-p53+/Bcl-2+; the exception was p53-null/Bcl-2- but expressed a low level of Fas (150 MESF). Activation of the cysteine protease CPP32 and cleavage of its substrate poly(ADP-ribose)polymerase(PARP) was also detected in Fas-S but not Fas-R lines. We obtained similar results from both the primary leukemic cells and the corresponding cell lines infive cases: overexpression of Fas and Fas-sensitivity were present in mt-p53+/Bcl-2- but not wt-p53+/Bcl-2+ cells. These results suggest that some pediatric ALL cells expressing mt-p53+ may be sensitive to Fas-mediated apoptosis due to high levels of Fas expression and lack of Bcl-2, and further suggest thatmolecular methods of activating Fas may be useful for therapy of refractory ALL with the Fas+/mt-p53+ phenotype.

PURPOSE: Forty percent of cases of retinoblastoma, a childhood malignancy of theretina, are linked to the inheritance of a mutant allele of the retinoblastoma susceptibility gene Rb1. tumor penetrance varies among carriers in different family pedigrees, indicating that other genetic factors may modify risk for occurrence of retinoblastoma. This study was undertaken to determine whether multiple genetic loci modify the risk for retinoblastoma in mice. METHODS: A line of alphaAcry-HPV16E6/E7 transgenic mice expressing the human papillomavirus type16 E6 and E7 oncogenes (HPV-16 E6 and E7) ectopically in the retina was characterized. E6 and E7 proteins bind to and inactivate the cellular tumor suppressor proteins p53 and Rb, respectively. RESULTS: Retinoblastomas developedrarely when the alphaAcry-HPV16E6/E7 transgene was maintained on the FVB background, but tumors arose with high frequency on C57BL/6 X FVB and C3H x FVB F1 hybrid backgrounds. The incidence of retinoblastoma in the LHbeta-TAG transgenic mice, which express simian virus 40 large tumor antigen (SV40 T-ag), was also influenced by the FVB and C57BL/6 backgrounds. Resistance of the alphaAcry-HPV16E6/E7 FVB mice to retinoblastoma mapped in part to the retinal degeneration (rd) locus. However, multiple genetic experiments indicate that resistance to retinoblastoma depends on additional loci in FVB mice. CONCLUSIONS: Multiple cellular genes can modify risk for retinoblastoma in mice.