4613

MYCN

MODED|N-myc|NMYC|ODED|bHLHe37;v-myc myelocytomatosis viral related oncogene, neuroblastoma derived (avian);MYCN;v-myc myelocytomatosis viral related oncogene, neuroblastoma derived (avian)

N-myc proto-oncogene protein|class E basic helix-loop-helix protein 37|neuroblastoma MYC oncogene|neuroblastoma-derived v-myc avian myelocytomatosis viral related oncogene|oncogene NMYC|pp65/67|v-myc avian myelocytomatosis viral related oncogene, neurobla

2p24.3

protein-coding

Melanotic neuroectodermal tumor of infancy is a rare but well-recognized entity in pediatric pathology. However, the relationship of this tumor to other pediatric small cell tumors with neuroectodermal features (such as neuroblastoma, Ewing sarcoma/peripheral primitive neuroectodermal tumor, and desmoplastic smallround cell tumor) is undetermined. Molecular genetic studies of melanotic neuroectodermal tumor of infancy have not been reported. We studied three typical cases of melanotic neuroectodermal tumor of infancy in an attempt to link this tumor to other small cell tumors with well-characterized molecular genetic changes. Tests performed included: detection of MYCN gene amplification and deletion of 1p (all 3 cases), and presence of the t(11;22)(q24;q12) and the t(11;22)(p13;q12) translocations (2 of 3 cases). None of these tests yielded positive results. Thus, there is no genetic basis at present to link melanotic neuroectodermal tumor of infancy to neuroblastoma, Ewing sarcoma/peripheral primitive neuroectodermal tumor, or desmoplastic small round cell tumor.

BACKGROUND: Improved survival with pediatric malignancies has been positively influenced by multidisciplinary cooperative studies using surgery, chemotherapy,and radiation therapy, but one-third of ALL children with cancer succumb to their condition. The identification of biologic and genetic characteristics as risk factors for the various tumors has led to changes in treatment using risk-based management as the template for care. STUDY DESIGN: The purpose of this report isfourfold: (1) to review survival data concerning three solid malignant tumors ofchildhood (Wilms' tumor, rhabdomyosarcoma, and neuroblastoma), (2) to describe important prognostic genetic and biologic risk factors for each tumor, (3) to update changes in staging criteria, and (4) to familiarize the reader with the concept of risk-based management, which individualizes treatment in an attempt to maximize survival and minimize longterm morbidity. RESULTS: The overall survivalrates for Wilms' tumor, rhabdomyosarcoma, and neuroblastoma are currently 90%, 70%, and 40%, respectively. Most patients with Wilms' tumor have favorable histology and survive after nephrectomy and chemotherapy, but 10% have poor prognostic variables, including unfavorable (anaplastic) histology, chromosomal loss on 1p and 16q, and diploidy. Instances of lung or liver metastases, major tumor spillage during resection, remote lymph node involvement, and bilateral tumors have worse outcomes. Rhabdomyosarcoma is associated with chromosomal translocation of t(2:13) in alveolar types, the p53 tumor suppressor gene, and 11p15. Survival is dependent on the tumor site and pretreatment clinical group. Orbit, paratesticular, vulvar, and vaginal tumors have a good prognosis, but other genitourinary tumors, extremity and trunk lesions, and parameningeal head and neck tumors have a worse prognosis. Survival rates by clinical group are stage I, 93%; II, 81%; III, 73%; and IV, 30%. Resectability, lymph node involvement, DNA ploidy, and pretreatment TNM staging affect outcomes. Neuroblastoma is an embryonal tumor with bizarre behavior and can regress, mature, or rapidly progress. Most patients have advanced disease at diagnosis. Neuroblastoma is associated with loss of heterozygosity on chromosome 1p36 and occasionally deletions on 14q and 17q. Survival is affected by age and stage (atless than 1 year, stages I [95% to 100%], II [85% to 90%], and IV-S [more than 80%] do better) and other risk factors. Patients with advanced disease (older than 1 year, stage III [70%], and stage IV [12%]) often have amplification of the N-myc oncogene, diploid tumors, 1p36 deletion, and unfavorable histology and fare worse. CONCLUSIONS: On the basis of these data, children with solid tumors are currently categorized into low-, intermediate-, and high-risk groups. Newer protocols individualize treatment using risk factors as predictors of outcomes. Risk-based management allows the clinician to weigh the risks and benefits of treatment for each patient to maximize survival, minimize longterm morbidity, and improve the quality of life.

BACKGROUND: Improved survival with pediatric malignancies has been positively influenced by multidisciplinary cooperative studies using surgery, chemotherapy,and radiation therapy, but one-third of ALL children with cancer succumb to their condition. The identification of biologic and genetic characteristics as risk factors for the various tumors has led to changes in treatment using risk-based management as the template for care. STUDY DESIGN: The purpose of this report isfourfold: (1) to review survival data concerning three solid malignant tumors ofchildhood (Wilms' tumor, rhabdomyosarcoma, and neuroblastoma), (2) to describe important prognostic genetic and biologic risk factors for each tumor, (3) to update changes in staging criteria, and (4) to familiarize the reader with the concept of risk-based management, which individualizes treatment in an attempt to maximize survival and minimize longterm morbidity. RESULTS: The overall survivalrates for Wilms' tumor, rhabdomyosarcoma, and neuroblastoma are currently 90%, 70%, and 40%, respectively. Most patients with Wilms' tumor have favorable histology and survive after nephrectomy and chemotherapy, but 10% have poor prognostic variables, including unfavorable (anaplastic) histology, chromosomal loss on 1p and 16q, and diploidy. Instances of lung or liver metastases, major tumor spillage during resection, remote lymph node involvement, and bilateral tumors have worse outcomes. Rhabdomyosarcoma is associated with chromosomal translocation of t(2:13) in alveolar types, the p53 tumor suppressor gene, and 11p15. Survival is dependent on the tumor site and pretreatment clinical group. Orbit, paratesticular, vulvar, and vaginal tumors have a good prognosis, but other genitourinary tumors, extremity and trunk lesions, and parameningeal head and neck tumors have a worse prognosis. Survival rates by clinical group are stage I, 93%; II, 81%; III, 73%; and IV, 30%. Resectability, lymph node involvement, DNA ploidy, and pretreatment TNM staging affect outcomes. Neuroblastoma is an embryonal tumor with bizarre behavior and can regress, mature, or rapidly progress. Most patients have advanced disease at diagnosis. Neuroblastoma is associated with loss of heterozygosity on chromosome 1p36 and occasionally deletions on 14q and 17q. Survival is affected by age and stage (atless than 1 year, stages I [95% to 100%], II [85% to 90%], and IV-S [more than 80%] do better) and other risk factors. Patients with advanced disease (older than 1 year, stage III [70%], and stage IV [12%]) often have amplification of the N-myc oncogene, diploid tumors, 1p36 deletion, and unfavorable histology and fare worse. CONCLUSIONS: On the basis of these data, children with solid tumors are currently categorized into low-, intermediate-, and high-risk groups. Newer protocols individualize treatment using risk factors as predictors of outcomes. Risk-based management allows the clinician to weigh the risks and benefits of treatment for each patient to maximize survival, minimize longterm morbidity, and improve the quality of life.

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.

Neuroblastoma is a childhood malignancy originating from cells of the sympathetic nervous system, exhibiting a marked diversity in outcome, with spontaneous regression at one end of the spectrum and severe disease and death at the other end. Features associated with frequent recurrence, a poor prognosis, and high tumor stage are loss of heterozygosity in the distal region of chromosome 1p andamplification of the N-myc gene. Patched 2 is a novel homologue to the tumor suppressor gene Patched 1, and has been mapped to 1p32-34, a part of chromosome 1 frequently deleted in high stage neuroblastoma tumors. RT-PCR analysis of 9 neuroblastoma cell lines showed expression of both Patched 1 and 2. We analyzed 14, mainly high stage, neuroblastoma tumors for mutations in the Patched 2 gene with denaturing HPLC using the Wave DNA fragment analysis system. In four tumor samples variations were detected within the coding sequence, and two of them gave rise to amino-acid substitutions. These variations were, however, also detected in normal DNA from the respective patients. We conclude that Patched 2 is expressed, but not frequently mutated, in high stage neuroblastomas and is therefore not likely to be involved in the genesis of this tumor.

Caspase 8 is a cysteine protease regulated in both a death-receptor-dependent and -independent manner during apoptosis. Here, we report that the gene for caspase 8 is frequently inactivated in neuroblastoma, a childhood tumor of the peripheral nervous system. The gene is silenced through DNA methylation as well as through gene deletion. Complete inactivation of CASP8 occurred almost exclusively in neuroblastomas with amplification of the oncogene MYCN. Caspase 8-null neuroblastoma cells were resistant to death receptor- and doxorubicin-mediated apoptosis, deficits that were corrected by programmed expression of the enzyme. Thus, caspase 8 acts as a tumor suppressor in neuroblastomas with amplification of MYCN.

The significant progress made in pediatric oncology during recent years has beendue to a major breakthrough in the field of molecular biology and the introduction of new therapeutic strategies that take into account both the quality and the duration of life. Molecular biology has already been instrumental in more fully categorizing the 'small round-cell tumor' group, and in reclassifying the 'Ewing family' tumors. It also provides a valuable tool for the prognostic evaluation of neuroblastomas through the analysis of the N-myc oncogene. In addition, it has permitted the identification of the Li-Fraumeni syndrome of predisposition to cancer in the child, thereby raising the problematical ethical issue of communicating relevant information to subjects atrisk. Two examples illustrate innovative strategic concepts: 1) Burkitt's lymphoma, or an example of the successful de-intensification of treatment; and 2) brain tumors in young children, regarding which the desire to improve the quality of life has led to innovative attempts to replace radiotherapy by chemotherapy. Considerable progress has been made in the field of neuropsychology, thereby permitting an improved assessment of disorders and a better management of rehabilitation programs. New anti-cancer agents and also chemo- and radiotherapythat spare healthy tissue are also being developed. Gene therapy and molecular biology will play a major role in future therapeutic strategies; and are now at the preclinical trial stage. This significant overall progress leads to a reconsideration of the organizational approach toward treatment of the pediatricpatient population suffering from cancer, and a critical assessment of disease management, which should take into account not only the technical aspects of thedisease but also familial and social considerations.

The significant progress made in pediatric oncology during recent years has beendue to a major breakthrough in the field of molecular biology and the introduction of new therapeutic strategies that take into account both the quality and the duration of life. Molecular biology has already been instrumental in more fully categorizing the 'small round-cell tumor' group, and in reclassifying the 'Ewing family' tumors. It also provides a valuable tool for the prognostic evaluation of neuroblastomas through the analysis of the N-myc oncogene. In addition, it has permitted the identification of the Li-Fraumeni syndrome of predisposition to cancer in the child, thereby raising the problematical ethical issue of communicating relevant information to subjects atrisk. Two examples illustrate innovative strategic concepts: 1) Burkitt's lymphoma, or an example of the successful de-intensification of treatment; and 2) brain tumors in young children, regarding which the desire to improve the quality of life has led to innovative attempts to replace radiotherapy by chemotherapy. Considerable progress has been made in the field of neuropsychology, thereby permitting an improved assessment of disorders and a better management of rehabilitation programs. New anti-cancer agents and also chemo- and radiotherapythat spare healthy tissue are also being developed. Gene therapy and molecular biology will play a major role in future therapeutic strategies; and are now at the preclinical trial stage. This significant overall progress leads to a reconsideration of the organizational approach toward treatment of the pediatricpatient population suffering from cancer, and a critical assessment of disease management, which should take into account not only the technical aspects of thedisease but also familial and social considerations.

Neuroblastoma (NB) is the most common pediatric neuroendocrine tumor, and it is characterized by a quite variable clinical course. We previously found a great variability in the expression of somatostatin receptor type 2 (sst2) in several human NB cell lines and primary tumors. In this report we investigated whether expression of sst2 is somehow related to clinical outcome. We performed a retrospective study on 54 patients with a maximum follow-up of 100 months. The concentration of specific messenger ribonucleic acid (mRNA) for sst2 was measured by competitive RT-PCR and validated, in a small subset of samples, by quantitative imaging of gene (in situ hybridization) and protein (immunohistochemistry) expression. We found that sst2 mRNA was variably expressed in ALL NB tumors (range, 2.5 x 10(5) to 8 x 10(9) molecules/microg RNA) with a relevant reduction in the more advanced stage (P < 0.01). Analysis of Kaplan-Meier curves indicated that sst2 expression is positively related to the overall (P < 0.0001) and event-free (P < 0.0001) survival. expression of sst2 was negatively related to tumor stage (P < 0.02) and MYCN amplification (P < 0.001),a poor prognostic factor. However, the prognostic information derived from sst2 is apparently independent from MYCN amplification, as assessed by stratifying sst2 values according to MYCN. In addition, the expression of sst2 was the only significant prognostic factor (P < 0.02) when it was included in a multivariate model containing other well known prognostic factors such as age, stage, and MYCN amplification. Hence, we propose that sst2 expression represents a new prognostic marker for NB. The main clinical value of a quantitative measure of sst2 lies inits ability to detect patients at low risk, independently from other prognostic factor, including MYCN amplification.

Neuroblastoma is the second most common solid malignancy of childhood. Enhanced expression of the amplified N-myc gene in the tumor cells may be associated withpoor patient prognosis and may contribute to tumor development and progression. The use of deferoxamine mesylate (DFO), an iron chelator, to treat neuroblastomais being investigated in national clinical studies. We show here by TUNEL assay and DNA laddering that DFO induces apoptosis in cultured human neuroblastoma cells, which is preceded by a decrease in the expression of N-myc and the altered expression of some other oncogenes (up-regulating c-fos and down-regulating c-myb) but not housekeeping genes. The decrease in N-myc expression is iron-specific but does not result from inhibition of ribonucleotide reductase, because specific inhibition of this iron-containing enzyme by hydroxyurea does not affect N-myc protein levels. Nuclear run-on and transient reporter gene expression experiments show that the decrease in N-myc expression occurs at the level of initiation of transcription and by inhibiting N-myc promoter activity. Comparison across neuroblastoma cell lines of the amount of residual cellular N-myc protein with the extent of apoptosis measured as pan-caspase activity after 48 h of iron chelation reveals no correlation, suggesting that the decrease in N-myc expression is unlikely to mediate apoptosis. In conclusion, chelation of cellular iron by DFO may alter the expression of multiple genes affecting the malignant phenotype by multiple pathways. Given the clinical importance of N-mycoverexpression in neuroblastoma malignancy, decreasing N-myc expression by DFO might be useful as an adjunct to current

The chimeric transcription factor E2a-Pbx1 is expressed as a result of the 1;19 chromosomal translocation in some 5% of cases of pediatric acute lymphoblastic leukemia. We investigated the biological and transcriptional consequences of forced expression of E2a-Pbx1 in the interleukin-3 (IL-3) dependent, bone marrow-derived cell line Ba/F3. We show that forced expression of E2a-Pbx1 induces apoptosis in Ba/F3 cells without apparent effects on cell cycle progression. This pro-apoptotic effect is enhanced on cytokine deprivation. Furthermore, using cDNA representational difference analysis (RDA), we show thatthese cellular effects are associated with marked induction of the gene NDRG1, which was previously identified as a target of transcriptional repression by N-myc and induction by the tumor suppressor protein p53. We identify a portion of the NDRG1 promoter capable of mediating transcriptional induction by E2a-Pbx1 and show that NDRG1 is also induced on simple IL-3 deprivation of BaF3 cells. Although we show that E2a-Pbx1 induction of NDRG1 is not impaired as a result oftargeting p53 using HPV E6, and therefore does not appear to be p53-dependent, our results overall are consistent with the notion that induction of NDRG1 by E2a-Pbx1 may represent part of an apoptotic or cytostatic cellular response to oncogene activation.

Neuroblastoma is a very common solid tumor which arises in childhood and shows an extreme heterogeneity at the clinical, histological and genetic levels. Besides age and stage, N-myc amplification and 1p deletion are prognostic factors of thedisease: in Europe, these genetic markers are used to conduct therapy. In France, N-myc amplification is a factor of bad prognosis which leads, in ALL forms of the disease including localised forms and metastatic forms of children aged of less than 1 year, to a myeloablative treatment with autologous hematopoietic stem cells transplantation. By contrast, N-myc amplification has no impact on the survival of children aged of more than 1 year with a poor prognosis (30% overallsurvival, 5 years) but this genetic abnormality is taken into account to treat primary tumor of these patients. In an attempt to find out prognostic factors ofthese aggressive forms of the disease, various pathways (apoptosis, differentiation angiogenesis, detoxication, immune response) have been recently surveyed, but studies have been carried out on a limited number of genes. Moreover, experimental models of human metastatic neuroblastoma have been obtained in which variations of genes transcript levels involved in these pathways, are observed. The current break-through of cDNA microarrays allows to develop a dynamic transcriptomic scanning of these models as well as of tumors and bone marrows from patients upon conventional chemotherapy. This technology will enable: i) to define molecular entities of the metastatic disease; ii) to apply adapted treatment; iii) to develop new therapeutic strategies.

Neuroblastoma is the most common malignant solid cancers in early childhood. Overexpression of the proto-oncogene, N-myc, has been reported to be correlated with more malignant course of the disease. Prothymosin alpha, a cellular proliferation-associated gene, is reported to be a target of myc and elevated inseveral malignant cells and tissues. expression of prothymosin alpha and N-myc messenger RNAs were evaluated by real-time reverse transcription polymerase chain reaction (RT-PCR) assay in 18 tumor samples from neuroblastoma using LightCycler. The data was analyzed in reference to clinicopathological factors. There was a tendency that higher prothymosin alpha transcripts levels in the tumor samples from younger patients (<1year.) when compared to the older group (>1 year.) (P=0.0845). There was no relationship between prothymosin alpha gene expression and gender (P=0.3029), mass screening case or not (P=0.3007), or stage. The prothymosin alpha mRNA expression levels were correlated with N-myc mRNA levels (P=0.006). Thus we suggest that prothymosin alpha plays an active role as a target of N-myc in neuroblastoma.

Neuroblastomas that overexpress N-Myc due to amplification of the MYCN oncogene are aggressive tumors that become very resistant to treatment by chemotherapy and irradiation. to identify tumor suppressor genes in this group of neuroblastomas we analyzed the expression and function of both apoptosis-related cell cycle regulatory genes in cell lines and patient tumor samples. We found that in a high percentage of neuroblastoma cell lines and patient samples with amplified MYCN, caspase-8 mRNA is not expressed. The caspase-8 gene, CASP8, was deleted or silenced by methylation in the neuroblastoma cell lines while methylation of itspromoter region was the predominant mechanism for its inactivation in the patient tumor samples. Reintroduction of caspase-8 into the neuroblastoma cell lines resensitized these cells to drug-induced and survival factor dependent apoptosis. Subsequently others have also shown that caspase-8 is silenced by methylation inneuroblastoma and peripheral neural ectodermal tumors, and that the caspase-9 regulator Apaf-1 is silenced by methylation in melanoma cell lines and patient samples. We conclude that caspase-8 acts as a tumor suppressor gene in neuroblastomas, that its silencing provides a permissive environment for MYCN gene amplification once the tumors are treated with chemotherapeutic drugs/irradiation, and that expression of this gene in these tumor cells may be of clinical benefit. We also discuss the possible significance of the neural crest cell progenitor cell origin and the silencing of important apoptotic regulators via methylation in both neuroblastoma and melanoma tumors.

The aim of this study was to investigate gene expression changes in disseminatedneuroblastoma by cDNA array technique. Three stage IV neuroblastomas and one neuroblastoma cell line (SK-N-FI) were analyzed. expression profiles were confirmed by semiquantitative RT-PCR and in some instances by Northern blotting.Comparison of expression profiles identified several genes which were highly expressed as well as some which were down-regulated in tumor samples relatively to SK-N-FI cells. The tumors studied lacked N-myc overexpression, while showing up-regulation of basic transcription factors, growth factors and receptors such as NSEP, c-myc binding protein MM1, thymosin beta10 (TMSB10), TNF-R superfamily member 10A (TNFRSF10A) and FZ9. These results suggest that cDNA array technologyis a powerful tool to identify a set of genes involved in neuroblastoma genesis and progression. Thus, the sensitive cDNA array may provide new insight into many aspects of pediatric tumors and play crucial role in the administration of adjuvant therapy of patients with neuroblastoma.

Neuroblastoma is a neural crest-derived tumor of childhood with a serious prognosis; only 20% of patients with stage 4 disease survive 5 years from diagnosis. Mechanisms involved in neuroblastoma development are unclear, but theengagement of many neuroblastoma-related gene(s) is suggested by specific chromosomal alterations. Most prominent among these is the amplification of the MYCN oncogene and the deletion of the 1p36 region. Other genetic aberrations have been discovered over the years such as deletions of 11q and 14q and gain of 17q.Although tumor aggressiveness greatly depends on the most frequent genetic abnormalities, to date no neuroblastoma-related gene has been discovered. Neuroblastoma usually occurs sporadically, but 1.5% of ALL diagnosed cases show familial recurrence with an autosomal dominant inheritance and incomplete penetrance. A comparison between hereditary and sporadic neuroblastomas led Knudson and Strong to gather that the two-hit hypothesis, proposed for retinoblastoma, could be applied to neuroblastoma. To determine if the 1p36 region harbors a predisposition gene for familial neuroblastoma, we carried out linkage analysis at 1p36 loci in two families with recurrent neuroblastoma. Similarly, we analyzed loci of chromosome 16, where a predisposition locus was recently mapped. We also analyzed markers located close to several candidate genes (RET, NF1, GDNF, GFRA1, EDNRB, and EDN3) involved to a different extent inother neurocristopathies. Our findings indicate that the candidate chromosomal regions and genes analyzed are not in linkage with neuroblastoma.

Chromatin remodeling is one of the mechanisms by which gene expression is regulated developmentally. Chromatin structure is controlled at least in part bypost-translational modification of histones, as well as by chromodomain proteins. We have identified a novel gene encoding a protein with chromatin remodeling, helicase and DNA-binding motifs. This gene, called CHD5, is the fifth member of the CHD gene family identified in humans. This gene is most homologous to CHD3 and CHD4, which encode proteins that are part of the nucleosome remodeling and histone deacetylation (NuRD) complex. CHD5 is preferentially expressed in total brain, fetal brain, and cerebellum. It is also moderately expressed in the adrenal gland, but expression is undetectable in almost ALL other tissues examined. CHD5 maps within a small region of deletion on 1p36.3 in human neuroblastomas, a common pediatric tumor. We examined a panel of neuroblastoma cell lines for CHD5 expression, which was consistently low or undetectable in ALL these lines. expression was also examined in a panel of 137 primary neuroblastomas, and low expression was highly correlated with 1p deletion, MYCN amplification, advanced stage, and unfavorable histology. These findings suggestthat this gene may play a role in the development of the nervous system, and it may also play a role in the pathogenesis of neural tumors.

Neurofibromatosis type 1 (NF1) patients are susceptible to tumor development. Inthe present study we describe a child with NF1 and disseminated neuroblastoma whose death resulted from disease progression. The mother had cafe-au-lait spotssuggesting a familial NF1. Neuroblastoma cells showed MYCN amplification and chromosome 1p36 deletion, common features associated with tumor progression in this malignancy. The NF1 gene displayed a germline T --> C transition of intron 14 in both the proband and mother DNA. This mutation, not yet previously described, occurs in a splicing donor site and produces a new mRNA variant observed together with normal NF1 mRNA. Furthermore, the SSCP analysis of the NF1 gene in tumor cells showed a somatic deletion encompassing the intron 26 and 27bof the paternal NF1 allele. Hence, neuroblastoma cells displayed both somatic and germline mutation of the NF1 gene. Our data suggest that, although rare, neuroblastoma in patients with NF1 may display homozygous gene inactivation.#CI- Copyright 2003 Wiley-Liss, Inc.

PURPOSE: Therapy stratification based on genetic markers is becoming increasingly important, which makes commitment to the highest possible reliability of the involved markers mandatory. In neuroblastic tumors, amplification of the MYCN gene is an unequivocal marker that indicates aggressive tumor behavior and is consequently used for therapy stratification. To guarantee reliable and standardized quality of genetic features, a quality-assessment study was initiated by the European Neuroblastoma Quality Assessment (ENQUA; connected to International Society of pediatric Oncology) Group. Materials and METHODS: One hundred thirty-seven coded specimens from 17 tumors were analyzed in 11 Europeannational/regional reference laboratories using molecular techniques, in situ hybridization, and flow and image cytometry. tumor samples with divergent results were re-evaluated. RESULTS: Three hundred fifty-two investigations were performed, which resulted in 23 divergent findings, 17 of which were judged as errors after re-evaluation. MYCN analyses determined by Southern blot and in situ hybridization led to 3.7% and 4% of errors, respectively. tumor cell content wasnot indicated in 32% of the samples, and 11% of seemingly correct MYCN results were based on the investigation of normal cells (eg, Schwann cells). Thirty-eight investigations were considered nonassessable. CONCLUSION: This study demonstrated the importance of revealing the difficulties and limitations for each technique and problems in interpreting results, which are crucial for therapeutic decisions. Moreover, it led to the formulation of guidelines that are applicableto ALL kinds of tumors and that contain the standardization of techniques, including the exact determination of the tumor cell content. Finally, the group has developed a common terminology for molecular-genetic results.

BACKGROUND: Amplification of the N-myc oncogene is associated with adverse outcomes in the common childhood tumor, neuroblastoma. Because the transforming properties of Myc are related to its ability to modulate gene expression, the authors used cDNA microarrays to identify potential Myc target genes. METHODS: expression levels of 4608 genes were analyzed in a series of neuroblastoma cell lines. Identical analyses were performed in a panel of medulloblastoma cell lines to identify c-Myc targets and to determine the extent to which N-Myc targets andc-Myc targets were shared. Comparisons were made between cell lines with high levels versus low levels of Myc protein expression. RESULTS: Array analyses yielded 121 genes with increased expression levels (>or= 1.65-fold) and 9 genes with decreased expression levels in N-Myc-expressing versus nonexpressing cell lines. Many of these were newly identified targets of biologic interest. Fifty percent of the N-Myc targets (60 of 121) were mutual c-Myc targets. A significant correlation between the level of N-myc and selected target gene expression was demonstrated independently in 27 neuroblastoma tumor samples and in an N-myc-inducible cell line system. CONCLUSIONS: A number of diverse pathways are modulated by N-Myc in neuroblastoma. Although, overall, there was significant correlation between myc and target transcript expression among cohorts of tumors, great variability in levels of target expression was seen among individual tumorsamples, and this biologic heterogeneity in the levels of target gene expressionmay offer insight into differences in the clinical behavior of neuroblastoma andmay prove to be of prognostic significance in the future.#CI- Copyright 2003 American cancer Society.DOI 10.1002/cncr.11584

PURPOSE: Amplification of the MYCN proto-oncogene is strongly correlated with poor outcome in neuroblastoma (NB), although deregulated MYCN is a potent inducer of apoptosis. BIN1 (2q14) encodes multiple isoforms of a Myc-interacting adaptorprotein that has features of a tumor suppressor, including the ability to inhibit Myc-mediated cell transformation and to promote apoptosis. We hypothesized that BIN1 may function as a suppressor gene in NB, because Bin1 is highly expressed in neural tissues and binds the Myc Box motifs that are conserved in MycN. EXPERMENTAL DESIGN: expression of MYCN, total BIN1, and BIN1 isoforms were determined in 56 primary NBs using the real-time PCR. expression was correlated with biological and genetic features. To determine the functional significance of BIN1 expression we ectopically expressed BIN1 isoforms in NB cell lines with andwithout MYCN amplification, and assessed clonogenic growth. RESULTS: Four predominant BIN1 isoforms resulting from alternative splicing of exon 12A (a neural tissue-specific exon) and exon 13 (a Myc-binding domain encoding exon) were variably expressed in the 56 primary NBs. expression of BIN1 was lower in: NBs with MYCN amplification (n = 10) compared with those without, P < 0.03; in International Neuroblastoma Risk Group high-risk NB (n = 19) compared with low- or intermediate-risk NB, P < 0.01; and in metastatic NB (n = 21) compared with localized NB, P < 0.06. BIN1 inactivation by deletion or genomic rearrangement was identified infrequently. Forced expression of BIN1 isoforms containing the Myc-binding domain (with or without exon 12A) inhibited colony formation in NB cell lines with MYCN amplification (P < 0.01) but not in those without. Forced expression of BIN1 isoforms with a MBD deletion did not inhibit colony formationin any cell line assessed. CONCLUSIONS: These data support that reduced BIN1 expression contributes to the malignant phenotype of childhood NB. As we reported previously, BIN1 may function to circumvent MycN-mediated apoptosis in NBs with MYCN amplification.

BACKGROUND: Human MYCN (hMYCN) oncogene amplification is a powerful predictor oftreatment failure in childhood neuroblastoma, and dysregulation of hMYCN proteinexpression appears to be critically involved in the pathogenesis of this disease. We used hMYCN antisense (AS) oligonucleotides to investigate, both in vitro and in vivo, the therapeutic potential of inhibiting hMYCN expression. METHODS: We transiently transfected human neuroblastoma IMR-32 cells, which have an amplified hMYCN gene, with fluorescently labeled hMYCN AS or scrambled (SCR) control oligonucleotides and used fluorescence-activated cell sorting to enrich for cellpopulations containing different levels of the oligonucleotides. We used fluorescence immunocytochemistry or reverse transcription polymerase chain reaction to assay gene expression levels and trypan blue exclusion to assay growth inhibition in the cell populations. We examined the effects of continuoustreatment for 6 weeks with AS or SCR oligonucleotides via subcutaneously implanted microosmotic pumps on tumor growth in a transgenic mouse model of hMYCN-induced neuroblastoma (n = 20 mice per group). ALL statistical tests were two-sided. RESULTS: IMR-32 cells treated with AS oligonucleotides had approximately half as much hMYCN protein and cell proliferation as either SCR oligonucleotide-transfected or mock-transfected controls; the differences were statistically significant. Transgenic mice treated with AS oligonucleotides had lower tumor incidence and statistically significantly lower tumor mass than SCR-treated or untreated control mice. Compared with control treatments, AS oligonucleotide treatment in vitro and in vivo was associated with decreased expression of hMYCN and putative hMYCN target genes but not with that of closelyrelated genes. Several AS oligonucleotide-treated mice developed tumors contralateral to the site of oligonucleotide administration, whereas SCR oligonucleotide-treated or untreated mice displayed bilateral tumor growth. CONCLUSIONS: Decreased expression of hMYCN protein is achievable with the use ofAS oligonucleotide treatment, even in the presence of hMYCN oncogene amplification. Antisense strategies targeting the hMYCN oncogene in vivo decrease mouse neuroblastoma tumorigenesis. Investigation of their clinical effect in children with neuroblastoma is warranted.

In the childhood cancer neuroblastoma (NB), the level of expression of the multidrug resistance-associated protein (MRP1) gene is strongly correlated with expression of the MYCN oncogene in primary NB tumors, suggesting that MRP1 may be a target for MYCN-mediated gene regulation. In this study, we show that MYCN induction in human NB cells results in increased MRP1 mRNA and protein levels, which in turn is accompanied by increased drug resistance and enhanced MRP1-mediated drug efflux. Furthermore, luciferase activity from MRP1 promoter/luciferase gene reporter constructs was significantly increased in NB cells with exogenous overexpression of MYCN, whereas activity was decreased in NB cells stably transfected with MYCN-antisense vectors. Decreased luciferase activity was observed with promoter constructs that lacked one or two E-box sequences or had E-box double point mutations, while a truncated MRP1 promoter lacking ALL three E-boxes exhibited only basal levels of activity. Specific electrophoretic mobility shifts of MRP1 E-box sequences were detected with nuclear extracts from NB cells with MYCN overexpression, and complex formation was inhibited with the addition of antibodies directed against MYCN or MYC. These findings indicate that by interacting with E-box elements within the promoter, MYCN can upregulate MRP1 expression and modulate drug resistance in NB.

BACKGROUND: Neuroblastoma is the most common extracranial solid malignancy in infancy and childhood, but the biological factors involved in its development and progression are still unclear. Transcriptional silencing of tumor suppressor genes mediated by hypermethylation of promoter CpG islands is a hallmark of human tumors. We addressed the clinical relevance of promoter hypermethylation in neuroblastoma. METHODS: We examined the methylation status of 45 candidate genesrepresentative of many cellular pathways in 10 neuroblastoma cell lines and of 10 of these genes in 145 tumor samples (118 of them were primary neuroblastomas). We used Fisher's exact test to examine the association of CpG island methylation and clinical subgroups and Kaplan-Meier analysis to determine the association between methylation and survival in primary tumors. Cluster analysis was used to group cell lines and tumors by gene methylation status. Bonferroni-corrected statistical tests were two-sided. RESULTS: Clustering of neuroblastoma cell lines on the basis of hypermethylation distinguished lines with MYCN amplification (a negative prognostic factor) from those without it (P =.012). Promoter hypermethylation of the developmental gene HOXA9 was associated with mortality in noninfant patients (P =.04) and in tumors lacking MYCN amplification (P =.023). Hypermethylation of the proapoptotic gene TMS1 and the cell cycle gene CCND2 wasassociated with stage 4-progressing tumors (P<.001), but the genes were never methylated in stage 4S tumors, which undergo spontaneous regression. Hypermethylation of the differentiation gene RARbeta2 was associated with patient survival (P =.032). Unsupervised hierarchical cluster analysis of ALL tumors based on methylation of the 10 genes separated several clinically relevant groups of tumors. CONCLUSIONS: Profiling the status of CpG island hypermethylation in human primary neuroblastomas may have clinicopathologic value.

Neuroblastomas, tumors of the sympathetic nervous system, account for 7-10% of the cancers of childhood. Genetic studies have shown, and this study has confirmed, that neuroblastomas are very heterogeneous; no single genetic change common to ALL neuroblastomas has yet been identified. One genetic aberration found frequently in this pediatric tumor is MYCN gene amplification. Recently weidentified a new subset of tumors showing MYCN gain (small increases in gene number arising from unbalanced translocation). To investigate whether gain precedes amplification or is an independent event, we surveyed 200 primary tumors for MYCN copy number with fluorescence in situ hybridization; 152 of 200 (76%) were MYCN single-copy tumors, whereas 48 of 200 (24%) tumors harbored MYCN abnormalities: 36 of the 48 (75%) had MYCN amplification and 12 (25%) had MYCN gain. Among the 36 with MYCN amplified gene, we found four that also showed gain. In three tumors exhibiting simultaneous gain and amplification, these two eventswere detected in neighboring cells. In the fourth case we detected only MYCN gain in metastatic neuroblasts in the bone marrow, but both MYCN amplification and gain in the primary tumor. The detailed study of these four cases suggests that there may be several different mechanisms leading to increase in MYCN copy number. Further studies in other human malignancies are necessary to determine whether simultaneous gain and amplification are specific to neuroblastoma or constitute a general mechanism by which tumor cells can acquire selective growthadvantage.

Neuroblastoma is a childhood cancer arising from the sympathetic nervous system.Disseminated neuroblastoma has a poor prognosis despite intensive multimodality treatment. Histone deacetylases (HDACs) were recently discovered as a potential target for pharmacological gene therapy in cancer. HDACs have an important function in regulating DNA packaging in chromatin, thereby affecting the transcription of genes. In this paper, we tested the efficacy of a newly developed histone deacetylase inhibitor, BL1521, on neuroblastoma in vitro by investigating the changes in: acetylation of histone H3, in situ HDAC activity, p21(WAF1/CIP1) and MYCN expression, metabolic activity, proliferation, morphology and the amount of apoptosis present. BL1521 inhibited the in situ HDAC activity of a panel of neuroblastoma cell lines by at least 85%. Western analysis showed an increase of histone H3 acetylation in neuroblastoma cells after incubation with BL1521. Northern analysis showed an increase in the expression of p21(WAF1/CIP1) and a decrease in the expression of MYCN in neuroblastoma cells after incubation with BL1521. Proliferation as well as the metabolic activity ofneuroblastoma cells decreased significantly in response to treatment with BL1521, regardless of the MYCN status of the cells. BL1521 induced poly-(ADP-ribose) polymerase cleavage in a time- and dose-dependent manner, indicating the induction of apoptosis. Furthermore, when compared to the HDAC inhibitors Trichostatin A and 4-phenylbutyrate, BL1521 has an intermediate efficacy. Our results show that BL1521 is a potent inhibitor of HDAC and that HDACs are an attractive target for selective chemotherapy in neuroblastoma.

Neuroblastoma (NBL), one of the most common childhood solid tumors, has a distinct nature in different prognostic subgroups. However, the precise mechanism underlying this phenomenon remains largely unknown. To understand the molecular and genetic bases of neuroblastoma, we have generated its cDNA libraries and identified a human ortholog of tubulin tyrosine ligase gene (hTTL/Nbla0660) as adifferentially expressed gene at high levels in a favorable subset of the tumor.Tubulin is subjected to several types of evolutionarily conserved posttranslational modification, including tyrosination and detyrosination. Tubulin tyrosine ligase catalyzes ligation of the tyrosine residue to the COOH terminus of the detyrosinated form of alpha-tubulin. The measurement of hTTL mRNA expression in 74 primary neuroblastomas by quantitative real-time reverse transcription-PCR revealed that its high expression was significantly associatedwith favorable stages (1, 2 and 4s; p = 0.0069), high TrkA expression (p = 0.002), a single copy of MYCN (p < 0.00005), tumors found by mass screening (p =0.0042), nonadrenal origin (p = 0.0042) and good prognosis (p = 0.023). The log-rank test showed that high expression of hTTL was an indicator of favorable prognosis (p = 0.026). Immunohistochemical analysis using specific antibodies generated by us demonstrated that tyrosinated tubulin (Tyr-tubulin), detyrosinated tubulin (Glu-tubulin) and hTTL as well as Delta2-tubulin were positive in favorable tumors, whereas only Delta2-tubulin was positive in the tumors with MYCN amplification. In an RTBM1 neuroblastoma cell line, hTTL was increased after treating the cells with bone morphogenetic protein 2 (BMP2) or all-trans retinoic acid (RA), which induced neuronal differentiation. These results suggest that the deregulated tubulin tyrosination/detyrosination cycle caused by decreased expression of hTTL is associated with inhibition of neuronaldifferentiation and enhancement of cell growth in the primary neuroblastomas with poor outcome.

BACKGROUND: Autoregulation of the myc gene family is a negative feedback mechanism known to occur at high levels of Myc expression. Loss of this mechanism and associated Myc overexpression has been observed in human tumors, thereby contributing to tumorigenesis. The childhood tumor neuroblastoma is characterized by N-myc amplification in aggressive and highly proliferative tumors that occur in a subset of patients. The precise molecular mechanism of autoregulation is unknown, and previous observations indicated that N-myc autoregulation was intact only in single-copy neuroblastoma cell lines. METHODS: Transient reporter assaysand trichostatin A (TSA) experiments were performed to evaluate several candidate genes, including Mxi1, c-myc promoter binding protein 1 (MBP-1), Miz, and histone deacetylase 2 (HDAC2), for their involvement in N-myc autoregulation. Mxi1 and HDAC2 were examined further for their expression levels and effects on endogenous N-myc levels. Finally, their recruitments to the N-myc promoter were investigated by chromatin immunoprecipitation (ChIP). RESULTS: The autoregulatory circuit wasoperative, even in amplified cell lines. Mxi1 consistently showed a modest effect in down-regulating N-myc in transient reporter assays. Overexpression of the c-myc, Mxi1, and mHDAC2 genes resulted in a threefold to fourfold decrease in endogenous N-myc levels. Mxi1 and HDAC2 were up-regulated by N-Myc in an myc-inducible cell line and in N-myc-expressing cell lines. In addition, down-regulation of the N-myc promoter was relieved in the presence of TSA. Increased association of HDAC2 with the autoregulatory region within the N-myc promoter by ChIP was observed upon down-regulation of endogenous N-myc. CONCLUSIONS: The autoregulatory circuit was intact in both amplified and single-copy neuroblastoma cell lines. Furthermore, myc gene autoregulation occurred through histone deacetylation.

Disseminated forms of neuroblastoma (NB), a tumor derived from neuroectodermal tissue, pose a major therapeutic challenge for pediatric oncology. By performinga comparative cDNA array analysis of metastatic neuroblasts versus primary xenograft from the human IGR-N-91 NB model, we were able to identify a set of downregulated developmental genes in metastatic neuroblasts. One of these genes was Wnt-5a, a member of the Wnt signaling pathway, known to be involved in the development of neural crest cells. Since we also found a significant decrease inWnt-5a mRNA in unfavorable versus favorable categories in 37 primary NB tumors (P<0.007), we wondered whether retinoic acid (RA), which has a role in neural crest induction and differentiation, might reverse the aberrant negative regulation of Wnt-5a in metastatic malignant neuroblasts. Following treatment with 10 muM RA for 6 days, the MYCN-amplified IGR-N-91 cell lines underwent neuronal differentiation as assessed by reduced MYCN gene expression and neuritic extension. In these conditions, data showed an upregulation of Wnt-5a and PKC-theta; isoform expressions. Our study highlights, for the first time, the involvement of Wnt-5a, which has a role in embryonic and morphogenetic processes, in the response of malignant neuroblasts to RA. In conclusion, we demonstrated that RA, which is used in the treatment of high-risk NB patients with recurrent/residual disease in the bone marrow, is able to upregulate Wnt-5a geneexpression.

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.

Neuroblastoma (NB) is the most common malignant solid tumor in childhood, and among ALL childhood malignancies is second in prevalence only to leukemia. In NBwe need to both make an accurate diagnosis and rapidly analyze the expression ofgenetic prognostic factors such as MYCN, H-ras, and trkA. Moreover, it has recently become important to analyze the expression of survivin mRNA, a member of the inhibitor of apoptosis protein family. expression of the survivin gene is related to tumorigenesis and inhibition of apoptosis in some malignant tumors. We investigated its expression by reverse transcription-polymerase chain reaction (RT-PCR) in NB cell lines (SK-N-SH, NB-39, and IMR-32), two normal blood cell samples, and 13 clinical NB tumor samples. ALL three NB cell lines had high levels of mRNA expression for this gene, but normal blood cells had no expression. We detected expression of survivin mRNA in 7 of the 13 NB tumor samples (54%). Two NB patients were in stage I disease, 6 in stage II, and 5 in stage IV(A). Quantitative analysis by RT-PCR revealed that the ratio between survivin mRNA and human glyceraldehyde-3-phosphate dehydrogenase (h-GAPDH) mRNA was very low in stages I and II (0-0.017). In contrast, in advanced NBs (stage IV(A)) the ratio was much higher (0-0.050). The prognoses of the three patients in the advanced stage who had high ratios of expression were poor. A high level of expression of survivin mRNA indicates a high grade of malignancy, high likelihood of recurrence, and poor prognosis.

Neuroblastoma is a childhood tumor with a poor survival in advanced stage disease despite intensive chemotherapeutic regimes. The new histone deacetylase (HDAC) inhibitor BL1521 has shown promising results in neuroblastoma. Inhibition of HDAC resulted in a decrease in proliferation and metabolic activity, induction of apoptosis and differentiation of neuroblastoma cells. In order to elucidate the mechanism mediating the effects of BL1521 on neuroblastoma cells, we investigated the gene expression profile of an MYCN single copy (SKNAS) and an MYCN amplified(IMR32) neuroblastoma cell line after treatment with BL1521 using the Affymetrixoligonucleotide array U133A. An altered expression of 255 genes was observed in both neuroblastoma cell lines. The majority of these genes were involved in geneexpression, cellular metabolism, and cell signaling. We observed changes in the expression of vital genes belonging to the cell cycle (cyclin D1 and CDK4) and apoptosis (BNIP3, BID, and BCL2) pathway in response to BL1521. The expression of 37 genes was altered by both BL1521 and Trichostatin A, which could indicate a common gene set regulated by different HDAC inhibitors. BL1521 treatment changedthe expression of a number of MYCN-associated genes. Several genes in the Wnt and the Delta/Notch pathways were changed in response to BL1521 treatment, suggesting that BL1521 is able to induce the differentiation of neuroblastoma cells into a more mature phenotype.

Neuroblastoma is a common childhood tumor comprising cases with rapid disease progression as well as spontaneous regression. Although numerous prognostic factors have been identified, risk evaluation in individual patients remains difficult. To define a reliable prognostic predictor and gene signatures characteristic of biological subgroups, we performed mRNA expression profiling of 68 neuroblastomas of ALL stages. expression data were analysed using support vector machines (SVM-rbf), prediction analysis of microarrays (PAM), k-nearest neighbors (k-NN) algorithms and multiple decision trees. SVM-rbf performed best of ALL methods, and predicted recurrence of neuroblastoma with an accuracy of 85% (sensitivity 77%, specificity 94%). PAM identified a classifier of 39 genes reliably predicting outcome with an accuracy of 80%. In comparison, conventionalrisk stratification based on stage, age and MYCN-status only reached a predictive accuracy of 64%. Kaplan-Meier analysis using the PAM classifier indicated a 5-year survival of 20 versus 78% for patients with unfavorably versus favorably predicted neuroblastomas, respectively (P = 0.0001). Significance analysis of microarrays (SAM) identified additional genes differentially expressed among subgroups. MYCN-amplification and high expression of NTRK1/TrkA demonstrated a strong association with specific gene expression patterns. Our data suggest thatmicroarray-derived data in addition to traditional clinical factors will be useful for risk assessment and defining biological properties of neuroblastoma.

Neuroblastoma (NB) is the most frequent extra-cranial solid tumor and the first cause of lethality in pre-school age children. NB accounts for 9-10% of pediatric tumors and affects more than ten thousand children a year. It originates from the sympathetic nervous system and is characterized by heterogeneous pathological and clinical presentation. Stage 4 NB represents approximately 50% of the cases and shows metastatic dissemination at onset; its prognosis is grim, with 20% of the patients surviving at 5 years from diagnosis in spite of aggressive chemotherapywith autologous hematopoietic stem cell support. Novel therapeutic strategies are urgently needed to improve the prognosis of stage 4 NB patients. Here we review the most promising approaches to NB treatment that have already reached clinicaltesting or have proved to be successful in preclinical models of the disease. ALL of these approaches are molecularly guided, since their rational development hasbenefited from the enormous amount of information on the biology of neuroblastoma gathered through molecular biology and genetics studies. The following topics are reviewed: MYCN oncogene amplification as parameter for therapeutic decision, minimal residual disease, immunotherapy, gene therapy, differentiation and apoptotic therapy, anti-angiogenic therapy, gene expression profiling as tool for generating novel therapeutic approaches. Although several efforts are still needed to reach a significant cure of patients with neuroblastoma, molecularly guided approaches have opened new ways to neuroblastoma treatment and can represent useful models for other cancers of either childhood or adulthood.

tumors of the central nervous system are the second most frequent malignancy of childhood, accounting for the majority of cancer-related deaths in this age group. Among these tumors, medulloblastomas (MB) remain in need of further genomic characterization toward understanding of pathogenesis and outcome predictors. Eight pediatric embryonal brain tumors were analyzed: five MB (one being desmoplastic), one PNET, one medulloepithelioma, and one ependymoblastoma.Analyses identified genomic imbalances, including the gain of 16p and the nonsyntenic coamplification of MYCN and TERT loci. More detailed FISH analysis showed that coamplification of MYCN and TERT in one of the MBs manifested as dispersed nuclear speckling, consistent with the presence of double minute chromosomes. There was considerable cell-to-cell copy number heterogeneity present, but it was clear that both genes were amplified concordantly. The amplification of oncogenes seems to play an important role in the pathogenesis of MB, and the association between MYCN and TERT amplifications and poor prognosis has not been well recognized. The uncharacteristic pattern of genomic imbalancesdetected in MB tumors may be a reflection of the characteristics of these tumorsoccurring in South America.

Combined analysis of gene expression array data and array-based comparative genomic hybridization data have been used in a series of 26 pediatric brain tumors to define up- and downregulated genes that coincide with losses, gains, and amplifications involving specific chromosome regions. Frequent losses were defined in chromosome arms 3q, 6q, 8p, 10q, 16q, 17p, and gains were identified in chromosome 7, and chromosome arms 9p and 17q. Amplification of a 2p region was seen in only one tumor, which corresponded to increased expression of the MYCN and DDX1 genes. To facilitate the analysis of the two data sets, we have developed a custom overlay tool that defines genes that are underexpressed in regions of deletions and overexpressed in regions of gain, across the genome andspecifically within regions showing recurrent involvement in medulloblastomas.#CI- Copyright 2006 Wiley-Liss, Inc.

PURPOSE OF REVIEW: Advances in tumor genetics have increasingly linked pediatricneoplasms with disordered mechanisms of normal development, supporting the modelof embryonal tumorigenesis. We provide a detailed discussion of two pediatric neural tumors, medulloblastoma and neuroblastoma, addressing tumorigenic causality and similarities within a pharmacological context. RECENT FINDINGS: expression profiling, elegant murine models, and chemical blockades of oncogenicsignaling pathways have encouraged a new generation of therapeutic approaches for tumor treatment. Recent data have further clarified regulation of neural developmental and factors triggering malignancy. SUMMARY: Medulloblastoma and neuroblastoma exemplify the current embryonal tumor model. Sonic hedgehog signaling is required for cerebellar development and its dysregulation is implicated in formation of medulloblastoma. The transcription factor Mycn orchestrates proliferation and differentiation of the developing peripheral neural crest. Amplification of the MYCN gene is the predominant marker for aggressive neuroblastoma, and correlates with poor prognosis. Current evidence suggests that Mycn is also the primary executor of Sonic hedgehog signaling in the cerebellum and that the Sonic hedgehog pathway regulates levels of both MYCNmRNA and Mycn protein product independently. Destabilization of Myc through inhibition of phosphoinositide 3-kinase signaling exhibits promise not only in medulloblastoma and neuroblastoma, but in a wide range of Myc-driven tumors.

PURPOSE OF REVIEW: Advances in tumor genetics have increasingly linked pediatricneoplasms with disordered mechanisms of normal development, supporting the modelof embryonal tumorigenesis. We provide a detailed discussion of two pediatric neural tumors, medulloblastoma and neuroblastoma, addressing tumorigenic causality and similarities within a pharmacological context. RECENT FINDINGS: expression profiling, elegant murine models, and chemical blockades of oncogenicsignaling pathways have encouraged a new generation of therapeutic approaches for tumor treatment. Recent data have further clarified regulation of neural developmental and factors triggering malignancy. SUMMARY: Medulloblastoma and neuroblastoma exemplify the current embryonal tumor model. Sonic hedgehog signaling is required for cerebellar development and its dysregulation is implicated in formation of medulloblastoma. The transcription factor Mycn orchestrates proliferation and differentiation of the developing peripheral neural crest. Amplification of the MYCN gene is the predominant marker for aggressive neuroblastoma, and correlates with poor prognosis. Current evidence suggests that Mycn is also the primary executor of Sonic hedgehog signaling in the cerebellum and that the Sonic hedgehog pathway regulates levels of both MYCNmRNA and Mycn protein product independently. Destabilization of Myc through inhibition of phosphoinositide 3-kinase signaling exhibits promise not only in medulloblastoma and neuroblastoma, but in a wide range of Myc-driven tumors.

Neuroblastoma is one of the most common solid tumors in childhood. With the aim of developing a targeting vector for neuroblastoma, we cloned and characterized an enhancer in the 5'-flanking regions of the MASH1 gene by a random-trap methodfrom a 36 kb cosmid DNA. The enhancer-containing clone was identified by the expression of GFP when transfected into neuroblastoma cell lines. The enhancer-luciferase activity is higher in neuroblastoma cell lines, IMR32, BE2 and SH-SY5Y, compared with those in non-neuroblastoma cell lines, U1242 glioma, N417 small cell lung cancer and EOMA hemangioma. The core enhancer was determined within a 0.2 kb fragment, yielding three- to fourfold higher activity than that of the MASH1 promoter alone in IMR32 and BE2. This area possesses GATA- and CREB-binding sites, as well as the E-box. EMSA on this area demonstrated that CREB/ATF could bind the DNA. Chromatin immunoprecipitation assay revealed that N-myc, CREB, and co-activators CBP and PCAF, but not HDAC1, are bound to the core enhancer at the same time as the co-activators and N-myc bind to the promoter. This supports the idea that the commonly overexpressed genes HASH1 and N-myc areregulated in concert, confirming their importance as prognostic markers or targets for therapy.

Wilms tumor (WT) is one of the most common solid tumors in childhood. It is characterized by a nonrandom pattern of chromosomal aberrations whose clinical significance is still uncertain. To gain further insight into different genetic events and their corresponding biological role, conventional cytogenetics and array comparative genomic hybridization (array CGH) were performed on 13 tumor samples. In two of these, array CGH revealed, together with other aberrations, alow-level amplification and an unbalanced gain in the region of chromosome bands2p23 approximately p24 that encompass the MYCN gene. Both events were confirmed with a MYCN-specific fluorescence in situ hybridization probe, which showed a signal pattern consistent with a small homogenous staining region in one case. In addition, mRNA expression levels for MYCN were determined by quantitative reverse-transcriptase polymerase chain reaction and revealed that gain of chromosomal material was reflected in enhanced levels of MYCN mRNA in both tumors, whereby also additional tumors showed increased MYCN expression. Therefore, our findings suggest that WT is an additional childhood tumor where MYCN gain might play an important role in tumor development.

Human retinoblastoma is a pediatric cancer initiated by RB gene mutations in thedeveloping retina. We have examined the origins and progression of retinoblastoma in mouse models of the disease. Retina-specific inactivation of Rb on a p130-/- genetic background led to bilateral retinoblastoma with rapid kinetics, whereas on a p107-/- background Rb mutation caused predominantly unilateral tumors that arose with delayed kinetics and incomplete penetrance. In both models, retinoblastomas arose from cells at the extreme periphery of the murine retina. Furthermore, late retinoblastomas progressed to invade the brain and metastasized to the cervical lymph nodes. Metastatic tumors lacking Rb and p130 exhibited chromosomal changes revealed by representational oligonucleotide microarray analysis including high-level amplification of the N-myc oncogene. N-myc was found amplified in three of 16 metastatic retinoblastomas lacking Rb and p130 aswell as in retinoblastomas lacking Rb and p107. N-myc amplification ranged from 6- to 400-fold and correlated with high N-myc-expression levels. These murine models closely resemble human retinoblastoma in their progression and secondary genetic changes, making them ideal tools for further dissection of steps to tumorigenesis and for testing novel therapies.

PURPOSE: Neuroblastoma is a common pediatric tumor that is derived from improperly differentiated neural crest cells (NCC). We recently revealed that endocrine gland-derived vascular endothelial growth factor/prokineticin-1 (EG-VEGF/Prok-1) is a key factor mediating the growth and differentiation of enteric NCCs during development. In this report, we further elucidate its role in neuroblastoma progression. EXPERIMENTAL DESIGN: We studied the expression and copy number of EG-VEGF/Prok-1 receptors (PK-R1 and PK-R2) in 26 neuroblastoma tumors by real-time reverse transcription-PCR and immunohistochemical analysis. Implication of EG-VEGF/Prok-1 signaling in neuroblastoma progression was furthershown in a neuroblastoma cell line (SK-N-SH). RESULTS: We found that ALL neuroblastoma samples from stages II to IV expressed both PK-R1 and PK-R2. Kruskall-Wallis signed rank tests revealed that the expression level of PK-R1 transcript is associated with the stages and metastasis of the neuroblastoma (P<0.05), and PK-R2 is persistently higher in advanced-stage neuroblastoma samples. About 38% of the neuroblastoma tumors (10:26) possessed MYCN amplification, whereas no PK-R1 and PK-R2 amplifications were detected, suggesting that the overexpression of the receptors was not due to gene amplification. Subsequent functional studies showed that EG-VEGF/Prok-1 activates the Akt pathway to induce the proliferation of neuroblastoma cells. Targeted down-regulation studies revealed that EG-VEGF/Prok-1-mediated proliferation requires the presence of these two receptors, and that PK-R2 is essential for inhibiting apoptosis. In vitro migration and invasion assays also indicated thatEG-VEGF/Prok-1 significantly enhances the cell migration/invasion of SK-N-SH. CONCLUSIONS: Our study has shown for the first time that aberrant EG-VEGF/Prok-1signaling favors neuroblastoma progression and could be a potential target for future neuroblastoma treatment.

The childhood eye cancer retinoblastoma is initiated by the loss of both allelesof the prototypic tumor suppressor gene, RB1. However, a large number of cytogenetic and comparative genomic hybridization (CGH) studies have shown that these M1 and M2 mutational events--although necessary for initiation--are not the only genomic changes in retinoblastoma. Some of these subsequent changes, which we have termed M3 to Mn, are likely crucial for tumor progression not only in retinoblastoma but also in other cancers. Moreover, genes showing genomic changein cancer are more stable markers and, therefore, possible therapeutic targets than genes simply differentially expressed. In this review, we provide the firstcomprehensive summary of the genomic evidence implicating gain of 1q, 2p, 6p, and 13q, and loss of 16q in retinoblastoma oncogenesis, including karyotype, CGH, and microarray CGH data. We discuss the search for candidate oncogenes and tumor suppressor genes within these regions, including the candidates (KIF14, MDM4, MYCN, E2F3, DEK, CDH11, and others), plus associations between genomic changes and clinical parameters. We also review studies of other regions of the retinoblastoma genome, the epigenetic changes of aberrant methylation of MGMT, RASSF1A, CASP8, and MLH1, and the roles microRNAs might play in this cancer. Although many candidate genes have yet to be functionally validated in retinoblastoma, work in this field lays out a molecular cytogenetic pathway of retinoblastoma development. Candidate cancer genes carry diagnostic, prognostic,and therapeutic implications beyond retinoblastoma.

Synovial sarcoma accounts for between 6 and 10% of childhood sarcomas and histological diagnosis can be challenging, even for experienced pathologists. Several other tumors enter the differential diagnosis, including malignant peripheral nerve sheath tumor, Ewing sarcoma/primitive neuroectodermal tumor andundifferentiated sarcoma. Several recent reports utilizing expression array techniques have documented expression of the MYCN oncogene in synovial sarcoma. In order to more fully investigate this finding, a series of 12 synovial sarcomas and 29 other sarcomas (four malignant peripheral nerve sheath tumors, 15 Ewing sarcoma/primitive neuroectodermal tumors, 10 undifferentiated sarcomas) were examined for MYCN expression and gene amplification. By RT-PCR, nine of 12 synovial sarcomas (75%) expressed MYCN. Five synovial sarcomas (42%) expressed MYCN at high levels. Of the other sarcomas, one malignant peripheral nerve sheath tumor (25%) and five Ewing sarcoma/primitive neuroectodermal tumors (33%) expressed MYCN at low levels, and ALL other cases were negative for MYCN. None of the synovial sarcomas had genomic amplification, suggesting that high MYCN expression levels resulted from epigenetic phenomena. Examination of selected downstream targets of MYCN in synovial sarcoma revealed expression of MCM7 (minichromosome maintenance protein 7) in ALL synovial sarcomas, and expression of nestin (n=10; 83%), ID2 (inhibitor of DNA binding protein 2) (n=6; 50%) and MRP1 (multidrug resistance protein 1) (n=1; 8%) in a subset of synovial sarcomas. expression of downstream targets did not correlate with expression of MYCN. Neither MYCN nor expression of downstream targets significantly correlated with metastases at presentation, progression-free survival or overall survival in this small series. In summary, high levels of MYCN expression was useful for distinguishing synovial sarcoma from other childhood-spindled cell sarcomas withspecificity and sensitivity of 100 and 42%, respectively, in this series. The clinical and biological significance of this finding deserves further study.

Neuroblastoma (NB) is a frequently lethal tumor of childhood. MYCN amplificationaccounts for the aggressive phenotype in a subset while the majority have no consistently identified molecular aberration but frequently express MYC at high levels. We hypothesized that activated Wnt/beta-catenin (CTNNB1) signaling mightaccount for this as MYC is a beta-catenin transcriptional target and multiple embryonal and neural crest malignancies have oncogenic alterations in this pathway. NB cell lines without MYCN amplification express higher levels of MYC and beta-catenin (with aberrant nuclear localization) than MYCN-amplified cell lines. Evidence for aberrant beta-catenin-TCF transcriptional activity was demonstrated using expression profiles from 73 primary NBs. Findings included increased WNT ligands (WNT1, WNT6, WNT7A, WNT10B), DVL1 and TCF7 expression in high-risk NBs without MYCN amplification, consistent with canonical beta-cateninsignaling. More directly, Patterns of Gene expression and Gene Set Enrichment Analyses demonstrated beta-catenin target genes (for example, MYC, PPARD, NRCAM,CD44, TCF7) as coordinately upregulated in high-risk NBs without MYCN amplification in comparison to high-risk MYCN-amplified or intermediate-risk NBs, supporting pathway activation in this subset. Thus, high-risk NBs without MYCN amplification may deregulate MYC and other oncogenic genes via altered beta-catenin signaling providing a potential candidate pathway for therapeutic inhibition.

Analysis of hereditary and nonhereditary retinoblastoma led to the formulation of the two-hit hypothesis of cancer in the early 1970s. The two-hit hypothesis was validated in the 1980s when both copies of the RB1 gene were shown to be mutatedin hereditary and nonhereditary retinoblastoma. However, consistent genetic abnormalities other than RB1 mutations suggest that additional events may be required for the formation of these malignant tumors. For example, MYCN amplification has long been known to occur in both retinoblastoma and neuroblastoma tumors and is strongly associated with poor prognosis in neuroblastoma. The DEAD box gene, DEAD box 1 (DDX1), is often coamplified with MYCN in both these childhood tumors. Here, we examine possible roles for DDX1 overexpression in retinoblastoma and neuroblastoma.

Neuroblastoma (NBL), a pediatric tumor arising from precursor cells of the sympathetic nervous system, is characterized by numerous recurrent large-scale chromosomal imbalances. High resolution oligonucleotide array CGH analysis of NBL has previously identified microdeletions that are confined to the 5' UTR of the protein tyrosine phosphatase receptor D (PTPRD) gene, implicating this gene in the pathogenesis of these tumors. Here, we demonstrate that the 5' UTR of this gene, consisting of 11 noncoding exons, is also aberrantly spliced in >50% of NBL primary tumors and cell lines. The loss of exons from the 5' UTR region through aberrant splicing results in aberrant mRNA isoforms that are similar to those generated through microdeletions. The aberrant splicing or microdeletion of 5' UTR exons in such a high proportion of tumors indicates that loss of these exonsdys-regulates the mRNA sequence. To further validate the role of PTPRD in NBL, we have examined the expression of this gene in normal fetal adrenal neuroblasts (the cell of origin of NBL) and in tumors from patients with either low stage orhigh stage disease. This gene is expressed at lower levels in high stage NBL tumors, particularly those with amplification of MYCN, relative to low stage tumors or normal fetal adrenal neuroblasts, consistent with the possibility thatloss of the 5' UTR exons have destabilized the mRNA.#CI- (c) 2007 Wiley-Liss, Inc.

Neuroblastoma (NB) is the most common malignant solid tumor in childhood. There are well-recognized prognostic factors in NB such as age at diagnosis, organ of origin, stages, MYCN gene amplification, and expression of H-ras, trkA and survivin. Moreover, we investigated the expression of vascular endothelial growth factor (VEGF), tyrosine hydroxylase (TH), p53, stem cell factor (SCF) and c-kit of its receptor with quantitative real-time polymerase chain reaction (PCR) in 22 NBs and 4 other tumors (one malignant lymphoma, one malignant teratoma, and 2 rhabdomyosarcomas) samples. The correlation between patients' prognoses and the expression of TH or c-kit was newly recognized, particularly the good prognosis in patients in whom c-kit highly expressed and the poor prognosis contrarily associated with low or no expression, although the SCF of its ligand had no relationship with patient prognosis. It is possible that tumors without c-kit expression can not react with SCF (via the autocrine or paracrine system) and remain immature. It may be that this is a new critical clinical event in NB patients.

The Sonic hedgehog (Shh) pathway is aberrantly activated in a subset of the mostcommon malignant pediatric brain tumor, medulloblastoma (MB). Shh pathway activity is measured by expression of the target genes in the GLI family, MYCN and PTCH1, a tumor suppressor and negative regulator of the pathway. Promoter methylation of tumor suppressors is implicated in tumor formation by gene silencing. In this study, we examined whether the proximal promoter of the PTCH1gene (variant exon 1B) is methylated in some cases of MB. The cases in which we anticipated the highest likelihood of methylation were chosen based on gene expression of indicators of Shh pathway activity. Of 21 primary MBs, four exhibited robust mRNA expression of GLI1 and MYCN as well as low or absent PTCH1expression, suggesting Shh pathway activity in the absence of PTCH1. The methylation profile of these cases was determined by the bisulfite sequencing method and compared to the profiles of five unaffected pediatric cerebellum controls. Contrary to our hypothesis, there was no evidence of methylation in the PTCH1-1B promoter in the MB cases examined, nor was there methylation in the control cerebellum samples. Future directions include examination of distal regions of the PTCHlb promoter as well as alternative exon variants, most notably the CpG island containing PTCH1-1C promoter.

Multidrug resistance is a major obstacle to cancer treatment and leads to poor prognosis for the patient. Multidrug resistance-associated protein 1 (MRP1) transports a wide range of therapeutic agents as well as diverse physiological substrates and may play a role in the development of drug resistance in several cancers including those of the lung, breast and prostate, as well as childhood neuroblastoma. The majority of patients with neuroblastoma present with widely disseminated disease at diagnosis and despite intensive treatment, the prognosisfor such patients is dismal. There is increasing evidence that MRP1 is a MYCN target gene involved in the development of multidrug resistance in neuroblastoma. Given the importance of MRP1 overexpression in neuroblastoma, MRP1 inhibition may be a clinically relevant approach to improving patient outcome in this disease.

Somatically acquired chromosomal imbalances are a key feature of neuroblastoma, a heterogeneous pediatric solid tumor. Among these alterations, genomic amplification targeting the MYCN oncogene and observed in about 25-30% of the cases, strongly correlates with advanced stage and poor outcome. In this work, we have used BAC and SNP arrays as well as gene expression arrays to characterize amplifications in neuroblastoma. Eighty-eight distinct BACs defining high-level amplification events were identified in 65 samples, including 43 tumors and 22 cell lines. Although the highest recurrence was observed on chromosome 2, cloneson chromosomes 8, 12, 16, and 17 also revealed genomic amplification in several samples. A detailed analysis of the 2p22-2p25 MYCN containing region indicated highly complex patterns in a number of cases. Coamplifications involving MYCN and other regions were explored by FISH in three cell lines. High-resolution arrays then allowed us to further refine the mapping of 25 amplicons in 19 samples, either reducing the size of a single continuous amplicon or increasing the complexity by highlighting multiple noncontiguous regions of amplification. Combined analysis of gene expression profiling and array-CGH data indicated that12 to 25% of the genes that are targeted by genomic amplification are actually over-expressed in tumor cells, several of them having already been implicated incancer. Finally, our results suggest that the presence of amplicons localized outside of chromosome 2, in addition to MYCN amplification, may be linked to a particularly severe outcome in neuroblastoma patients.

BACKGROUND: Neuroblastoma is a very heterogeneous pediatric tumor of the sympathetic nervous system showing clinically significant patterns of genetic alterations. Favorable tumors usually have near-triploid karyotypes with few structural rearrangements. Aggressive stage 4 tumors often have near-diploid or near-tetraploid karyotypes and structural rearrangements. Whole genome approaches for analysis of genome-wide copy number have been used to analyze chromosomal abnormalities in tumor samples. We have used array-based copy number analysis using oligonucleotide single nucleotide polymorphisms (SNP) arrays to analyze the chromosomal structure of a large number of neuroblastoma tumors of different clinical and biological subsets. RESULTS: Ninety-two neuroblastoma tumors were analyzed with 50 K and/or 250 K SNP arrays from Affymetrix, using CNAG3.0 software. Thirty percent of the tumors harbored 1p deletion, 22% deletion of 11q, 26% had MYCN amplification and 45% 17q gain. Most of the tumors with 1p deletionwere found among those with MYCN amplification. Loss of 11q was most commonly seen in tumors without MYCN amplification. In the case of MYCN amplification, two types were identified. One type displayed simple continuous amplicons; the othertype harbored more complex rearrangements. MYCN was the only common gene in ALL cases with amplification. Complex amplification on chromosome 12 was detected intwo tumors and three different overlapping regions of amplification were identified. Two regions with homozygous deletions, four cases with CDKN2A deletions in 9p and one case with deletion on 3p (the gene RBMS3) were also detected in the tumors. CONCLUSION: SNP arrays provide useful tools for high-resolution characterization of significant chromosomal rearrangements in neuroblastoma tumors. The mapping arrays from Affymetrix provide both copy number and allele-specific information at a resolution of 10-12 kb. Chromosome 9p, especially the gene CDKN2A, is subject to homozygous (four cases) and heterozygous deletions (five cases) in neuroblastoma tumors.

The childhood cancer neuroblastoma arises in the developing sympathetic nervous system and is a genotypically and phenotypically heterogeneous disease. Prognostic markers of poor survival probability include amplification of the MYCN oncogene and an undifferentiated morphology. Whereas these features discriminatehigh- from low-risk patients with precision, identification of poor outcome low-and intermediate-risk patients is more challenging. In this study, we analyze two large neuroblastoma microarray datasets using a priori-defined gene expression signatures. We show that differential overexpression of Myc transcriptional targets and low expression of genes involved in sympathetic neuronal differentiation predicts relapse and death from disease. This was evident not only for high-risk patients but was also robust in identifying groups of poor prognosis patients who were otherwise judged to be at low- or intermediate-risk for adverse outcome. These data suggest that pathway-specific gene expression profiling might be useful in the clinic to adjust treatment strategies for children with neuroblastoma.

The central neurocytoma, a recently identified rare supratentorial brain tumor in young adults, is characterized by intraventricular location and a usually benignclinical course. In order to elucidate the histogenesis and differentiation potential of this neoplasm, we have undertaken an immunocytochemical and molecular biological study of four central neurocytomas. It was found by immunocytochemistry and immunoblotting that ALL tumors express neuron-specific enolase and synaptophysin. Western blots also revealed expression of the synaptic vesicle protein, synapsin I, neurofilament protein and glial fibrillary acidic protein in several neurocytomas which failed to exhibit immunoreactivity to these marker antigens on paraffin sections. Immunocytochemical reactions with antibodies to synaptophysin and glial fibrillary acidic protein on adjacent sections demonstrated coexpression in individual tumor cells. The neuronal form of the pp60src protein-tyrosine kinase, an oncogene-product specifically expressed in central nervous system neurons, was not detectable in two central neurocytomas investigated. N-myc, a proto-oncogene frequently amplified in childhood neuroblastomas, was present as a single copy gene in ALL central neurocytomas, indicating that amplification of this gene is not involved in the pathogenesis of the central neurocytoma. In accordance with ultrastructural evidence of synaptogenesis, we conclude that the central neurocytoma is a neuroectodermal tumor with consistent commitment for neuronal differentiation. Since these tumors retain a potential for additional glial differentiation, we propose an origin from bipotential progenitor cells in the periventricular matrix, which in the mammalian brain persists throughout adult life.

Rhabdomyosarcomas (RMS) are the most common pediatric soft tissue sarcomas. Theyresemble developing skeletal muscle and are histologically divided into two mainsubtypes; alveolar and embryonal RMS. Characteristic genomic aberrations, including the PAX3- and PAX7-FOXO1 fusion genes in alveolar cases, have led to increased understanding of their molecular biology. Here, we determined the effect of genomic copy number on gene expression levels through array comparative genomic hybridization (CGH) analysis of 13 RMS cell lines, confirmed by multiplex ligation-dependent probe amplification copy number analyses, combined with theircorresponding expression profiles. Genes altered at the transcriptional level bygenomic imbalances were identified and the effect on expression was proportionalto the level of genomic imbalance. Extrapolating to a public expression profiling dataset for 132 primary RMS identified features common to the cell lines and primary samples and associations with subtypes and fusion gene status. Genes identified such as CDK4 and MYCN are known to be amplified, overexpressed, and involved in RMS tumorigenesis. Of the many genes identified, those with likely functional relevance included CENPF, DTL, MYC, EYA2, and FGFR1. Copy number and expression of FGFR1 was validated in additional primary material and found amplified in 6 out of 196 cases and overexpressed relative to skeletal muscle and myoblasts, with significantly higher expression levels in the embryonal comparedwith alveolar subtypes. This illustrates the ability to identify genes of potential significance in tumor development through combining genomic and transcriptomic profiles from representative cell lines with publicly available expression profiling data from primary tumors.

Neuroblastomas are malignant childhood neoplasms that arise from derivatives of the neural crest. We report the characterization of a new neuroblastoma cell line, designated NBL-W, derived from the primary tumor of a patient with stage IVS disease (S. L. Cohn, C. V. Herst, H. S. Maurer, and S. T. Rosen, J. Clin. Oncol., 5: 1441-1444, 1987) according to the criteria of Evans [A. E. Evans, G. J. D'Angio, and J. Randolf, cancer (Phila.), 27: 374-378, 1971]. Neurite-bearing(N) and substrate-adherent (S) cell lines have been subcloned from the parent line. N and S cells can interconvert, and both cell types label with the neural crest cell surface marker antibody, HNK-1. Cells in the subcloned lines and in the parent line have been shown by Southern blot analysis to contain approximately 100 copies of the N-myc gene. Cytogenetic analysis shows a homogeneously staining region present on chromosome 19. Although these subclonesare of identical genotype, the S cells express lower amounts of N-myc mRNA and protein as compared to the N cells. N cells express several neuronal proteins including the neurotransmitter-processing enzymes tyrosine hydroxylase and dopamine beta-hydroxylase, the neuronal intermediate filament proteins peripherin and NF66/alpha-internexin, and the neural cell adhesion molecule. S cells generally lack neuronal markers but express the mesenchymal intermediate filament protein vimentin, and a small subset of the S cells express glial fibrillary acidic protein. Some S cells were labeled weakly with neural cell adhesion molecule antibody; others were negative. S cells did not express the glial marker S-100 or a melanocyte marker, tyrosinase. Thus, S cells express the neural crestmarker HNK-1 but do not express a set of antigens characteristic of any known cell type derived from the neural crest. These results are consistent with the suggestion that differential N-myc expression may be involved in the interconversion of N and S cells but indicate that the S cell phenotype need notrepresent a highly differentiated neural crest derivative.

Alveolar rhabdomyosarcoma (ARMS) is an aggressive pediatric cancer that is related to the skeletal muscle lineage and characterized by recurrent chromosomal translocations. Within the ARMS category, there is clinical and genetic heterogeneity, consistent with the premise that "primary" genetic events collaborate with "secondary" events to give rise to subsets with varying clinical features. Previous studies demonstrated that genomic amplification occurs frequently in ARMS. In the current study, we used oligonucleotide arrays to localize two common amplicons to the 2p24 and 12q13-q14 chromosomal regions. Based on the copy number array data, we sublocalized the minimum common regions of 2p24 and 12q13-q14 amplification to a 0.83 Mb region containing the DDX1 and MYCN genes, and a 0.55 Mb region containing 27 genes, respectively. Using fluorescent in situ hybridization assays to measure copy number of the 2p24 and 12q13-q14 regions in over 100 cases, we detected these amplicons in 13% and 12% of cases, respectively. Comparison with fusion status revealed that 2p24 amplification occurred preferentially in cases positive for PAX3-FOXO1 or PAX7-FOXO1 while 12q13-q14 amplification occurred preferentially in PAX3-FOXO1-positive cases. expression studies demonstrated that MYCN was usuallyoverexpressed in cases with 2p24 amplification while multiple genes were overexpressed in cases with 12q13-q14 amplification. Finally, although 2p24 amplification did not have a significant association with clinical outcome, 12q13-q14 amplification was associated with significantly worse failure-free andoverall survival that was independent of gene fusion status.

Neuroblastoma, derived from neural crest progenitor cells, is the most common extracranial solid tumor of childhood. Astrocyte elevated gene-1 (AEG-1) is a primary mediator of tumor progression and metastasis in several human cancers. In this study, we investigated the potential contribution of AEG-1 in human neuroblastoma pathogenesis. AEG-1 expression was significantly elevated in neuroblastoma patient-derived samples and neuroblastoma cell lines as compared with normal peripheral nerve tissues, normal astrocytes and immortalized melanocytes. Knockdown of AEG-1 by small interfering RNA reduced the tumorigenicproperties of highly aggressive neuroblastoma cells. Conversely, over-expressionof AEG-1 enhanced proliferation and expression of the transformed state in less aggressive neuroblastoma cells through activation of the phosphatidylinositol 3-kinase-Akt-signaling pathway and stabilization of MYCN. These provocative results indicate that AEG-1 may play a crucial role in the pathogenesis of neuroblastoma and could represent a potential target for therapeutic intervention.

Two genes have a synthetically lethal relationship when the silencing or inhibiting of 1 gene is only lethal in the context of a mutation or activation of the second gene. This situation offers an attractive therapeutic strategy, as inhibition of such a gene will only trigger cell death in tumor cells with an activated second oncogene but spare normal cells without activation of the second oncogene. Here we present evidence that CDK2 is synthetically lethal to neuroblastoma cells with MYCN amplification and over-expression. Neuroblastomas are childhood tumors with an often lethal outcome. Twenty percent of the tumors have MYCN amplification, and these tumors are ultimately refractory to any therapy. Targeted silencing of CDK2 by 3 RNA interference techniques induced apoptosis in MYCN-amplified neuroblastoma cell lines, but not in MYCN single copy cells. Silencing of MYCN abrogated this apoptotic response in MYCN-amplified cells. Inversely, silencing of CDK2 in MYCN single copy cells did not trigger apoptosis, unless a MYCN transgene was activated. The MYCN induced apoptosis after CDK2 silencing was accompanied by nuclear stabilization of P53, and mRNA profiling showed up-regulation of P53 target genes. Silencing of P53 rescued thecells from MYCN-driven apoptosis. The synthetic lethality of CDK2 silencing in MYCN activated neuroblastoma cells can also be triggered by inhibition of CDK2 with a small molecule drug. Treatment of neuroblastoma cells with roscovitine, aCDK inhibitor, at clinically achievable concentrations induced MYCN-dependent apoptosis. The synthetically lethal relationship between CDK2 and MYCN indicatesCDK2 inhibitors as potential MYCN-selective cancer therapeutics.

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 one of the most common solid tumors of childhood, arising from immature sympathetic nervous system cells. The clinical course of patients with neuroblastoma is highly variable, ranging from spontaneous regression to widespread metastatic disease. Although the outcome for children with cancer hasimproved considerably during the past decades, the prognosis of children with aggressive neuroblastoma remains dismal. The clinical heterogeneity of neuroblastoma mirrors the biological and genetic heterogeneity of these tumors. Ploidy and MYCN amplification have been used as genetic markers for risk stratification and therapeutic decision making, and, more recently, gene expression profiling and genome-wide DNA copy number analysis have come into thepicture as sensitive and specific tools for assessing prognosis. The applica tion of new genetic tools also led to the discovery of an important familial neuroblastoma cancer gene, ALK, which is mutated in approximately 8% of sporadictumors, and genome-wide association studies have unveiled loci with risk allelesfor neuroblastoma development. For some of the genomic regions that are deleted in some neuroblastomas, on 1p, 3p and 11q, candidate tumor suppressor genes havebeen identified. In addition, evidence has emerged for the contribution of epigenetic disturbances in neuroblastoma oncogenesis. As in other cancer entities, altered microRNA expression is also being recognized as an important player in neuroblastoma. The recent successes in unraveling the genetic basis ofneuroblastoma are now opening opportunities for development of targeted therapies.

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.

Neuroblastoma is the most common extracranial tumor of childhood, with about 650new cases each year in the United States. The clinical course of neuroblastoma is variable and depends on age at diagnosis, staging, histology, and specific genetic abnormalities, such as MYCN oncogene amplification or aberrations of chromosome 1p or 11q. A subset of tumors will undergo spontaneous regression, whereas others progress despite aggressive therapy. The varied clinical behaviorreflects genetic heterogeneity, with many possible gene candidates identified instudies using comparative genetic hybridization arrays, RNA expression microarrays, and genome-wide association studies. Recent studies implicated the anaplastic lymphoma kinase gene in the tumorigenesis of many familial and some sporadic cases of neuroblastoma. The International Neuroblastoma Risk Group developed a new staging and risk classification, with recommendations for analysis of biological markers in neuroblastoma. This review discusses the biology of these tumors, current and new risk classification, and staging recommendations, with a brief outline of preferred treatment strategies.

Neuroblastoma (NB) is a heterogeneous pediatric tumor. To better understand the biological pathways involved in the development of high-risk neuroblastoma, we performed parallel global protein and mRNA expression profiling on NB tumors of stage 4 MYCN-amplified (4+) and stage 1 MYCN-not-amplified (1-) using isotope-coded affinity tags (ICAT) and Affymetrix U133plus2 microarray, respectively. A total of 1461 proteins represented by 2 or more peptides were identified from the quantitative ICAT analysis, of which 433 and 130 proteins are up- or down-regulated, respectively, in 4+ tumor compared to the 1- tumor. pathway analysis of the differentially expressed proteins showed the enrichment of glycolysis, DNA replication and cell cycle processes in the up-regulated proteins and cell adhesion, nervous system development and cell differentiation processes in the down-regulated proteins in 4+ tumor; suggesting a less mature neural and a more invasive phenotype of 4+ tumor. Myc targets and ribosomal proteins are overrepresented in the 4+ tumors as expected; functional gene sets reported to be enriched in neural and embryonic stem cells are significantly enriched in the 4+ tumor, indicating the existence of a stemness signature in MYCN-amplified stage 4 tumor. In addition, protein and mRNA expression are moderately correlated (r = 0.51, p < 0.0001), as approximately half of the up-regulated proteins in 4+ tumor have elevated mRNA level (n = 208), and one-third of down-regulated proteins have lower mRNA expression (n = 47). Further biological network analysis revealed that the differentially expressed proteins closely interact with other proteins of known networks; the important role of MYCN is confirmed and other transcription factors identified in the network may have potential roles in the biology of NB tumor. We used global genomic and proteomic analysis to identify biologically relevant proteins and pathways important to NB progression and development that may provide new insights into the biology of advanced neuroblastoma.

BACKGROUND: Neuroblastoma, a cancer derived from precursor cells of the sympathetic nervous system, is a major cause of childhood cancer related deaths.The single most important prognostic indicator of poor clinical outcome in this disease is genomic amplification of MYCN, a member of a family of oncogenic transcription factors. METHODOLOGY: We applied MYCN chromatin immunoprecipitation to microarrays (ChIP-chip) using MYCN amplified/non-amplified cell lines as wellas a conditional knockdown cell line to determine the distribution of MYCN binding sites within ALL annotated promoter regions. CONCLUSION: Assessment of E-box usage within consistently positive MYCN binding sites revealed a predominance for the CATGTG motif (p<0.0016), with significant enrichment of additional motifs CATTTG, CATCTG, CAACTG in the MYCN amplified state. For cell lines over-expressing MYCN, gene ontology analysis revealed enrichment for the binding of MYCN at promoter regions of numerous molecular functional groups including DNA helicases and mRNA transcriptional regulation. In order to evaluate MYCN binding with respect to other genomic features, we determined the methylation status of ALL annotated CpG islands and promoter sequences using methylated DNA immunoprecipitation (MeDIP). The integration of MYCN ChIP-chip and MeDIP data revealed a highly significant positive correlation between MYCN binding and DNA hypermethylation. This association was also detected in regions of hemizygous loss, indicating that the observed association occurs on the same homologue. In summary, these findings suggest that MYCN binding occurs more commonly at CATGTG as opposed to the classic CACGTG E-box motif, and that disease associated over expression of MYCN leads to aberrant binding to additional weaker affinity E-box motifs in neuroblastoma. The co-localization of MYCN binding and DNA hypermethylation further supports the dual role of MYCN, namely that of a classical transcription factor affecting the activity of individual genes, and that of a mediator of global chromatin structure.

Caspase 8 is a cysteine protease regulated in both a death-receptor-dependent and -independent manner during apoptosis. Here, we report that the gene for caspase 8 is frequently inactivated in neuroblastoma, a childhood tumor of the peripheral nervous system. The gene is silenced through DNA methylation as well as through gene deletion. Complete inactivation of CASP8 occurred almost exclusively in neuroblastomas with amplification of the oncogene MYCN. Caspase 8-null neuroblastoma cells were resistant to death receptor- and doxorubicin-mediated apoptosis, deficits that were corrected by programmed expression of the enzyme. Thus, caspase 8 acts as a tumor suppressor in neuroblastomas with amplification of MYCN.

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.

The understanding of the molecular biology of human cancer has advanced rapidly in the last decade, in part due to discoveries in the rare, pediatric ocular tumor, retinoblastoma. RB studies have led to recognition of a class of human genes, the tumor suppressor genes, that are critical in the initiation and progression of the malignant process. mutations in the RB1 gene initiate RB and other specific tumors. They may also contribute to progressive stages of many other malignancies. The protein product of RB1 (p110RB1) is a basic regulator ofthe cell cycle. In the absence of normal protein, the cell proceeds to the next cell division without the potential to become quiescent. Understanding the genetics of RB has benefited the patients, as the precise identification of the RB1 mutations in families has led to accurate prediction of individuals at risk for RB tumors. It seems unlikely, in the foreseeable future, that direct geneticmanipulation of mutant RB1 genes will play a role in therapy, but complete understanding of the function of p110RB1 may eventually allow exploitation of its powerful antiproliferative effect. Other molecular genetic events in addition toRB1 mutations are documented in RB tumors, and may play a critical role in the full malignant phenotype. The oncogene, N-myc, is amplified in some RB tumors and is expressed in normal fetal retina. The cytogenetic abnormality, i(6p), is almost unique to RB tumors. The molecular and tissue-specific roles of these abnormalities are not yet known. Many RB tumors also acquire excessive expression of the cell surface membrane glycoprotein, p170, linked to multidrug resistance,whether or not the RB tumor has been exposed to chemotherapy. We anticipate thatways to avoid or counteract the drug resistance of excessive p170 expression will be developed for other pediatric tumors and eventually will be applied to chemotherapy for RB patients.

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.

Wilms tumor is one of the most common pediatric malignant tumors of the kidney. Although the WT1 gene, located at 11p13, has been proven to be implicated in thedevelopment of Wilms tumor, other genes such as MYCN are also involved. The purpose of this study is to genetically characterize a Wilms tumor metastasis xenotransplanted in nude mice. Immunogenotype evolution of the xenografts material was monitored for 29 months using molecular techniques, fluorescent in situ hybridization and multiplex ligation-dependent probe amplification, in addition to immunohistochemistry in tissue microarrays. Genetic alterations present in the original tumor and retained in the xenotransplanted tumor were located in +1q, +3, +6, -7p, +7q, +8, -9p, +9q, +12. The multiplex ligation-dependent probe amplification detected a nondeleted status of genes located close to WT genes, except for a deletion of the EGFR gene (located at 7p11.2) and the GHRHR gene (located at 7p15), both flanking the WT5 gene. The MYCN gene (2p24 exon 3) and DDX1 gene (2p24 exons 2, 7, 15, and 24) were gained in passage 4 and the following passages. MYCN expression was positive from the beginning, without evidence of MYCN gain by fluorescent in situ hybridization. Histopathologic and growth rate changes were observed at those passages where low extra copy number of MYCN was present. In addition to other genetic abnormalities, the WT5 gene located at 7p13-14 is deleted and the MYCN gene gainbegan after 16 months in vivo evolution in athymic nude mice. MYCN is already used as a stratifying marker in neuroblastomas, and it may be also useful in implementing MYCN testing in prospective studies of Wilms tumors.

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.

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.

Neuroblastoma is the most common extracranial solid tumor of childhood. One important factor that predicts a favorable prognosis is the robust expression ofthe TRKA and p75NTR neurotrophin receptor genes. Interestingly, TRKA and p75NTR expression is often attenuated in aggressive MYCN-amplified tumors, suggesting acausal link between elevated MYCN activity and the transcriptional repression ofTRKA and p75NTR, but the precise mechanisms involved are unclear. Here, we show that MYCN acts directly to repress TRKA and p75NTR gene transcription. Specifically, we found that MYCN levels were critical for repression and that MYCN targeted proximal/core promoter regions by forming a repression complex with transcription factors SP1 and MIZ1. When bound to the TRKA and p75NTR promoters,MYCN recruited the histone deacetylase HDAC1 to induce a repressed chromatin state. Forced re-expression of endogenous TRKA and p75NTR with exposure to the HDAC inhibitor TSA sensitized neuroblastoma cells to NGF-mediated apoptosis. By directly connecting MYCN to the repression of TRKA and p75NTR, our findings establish a key pathway of clinical pathogenicity and aggressiveness in neuroblastoma.#CI- (c) 2010 AACR.

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.

Neuroblastoma is the most common childhood solid tumor, yet current treatment approaches have not been able to effectively control this cancer. Amplification and overexpression of MYCN have been shown to be closely related with high risk and poor prognosis in neuroblastoma. This suggests that MYCN is an important target for the antitumor therapy. Recently, vector-based RNA interference (RNAi)systems have been successfully used to eliminate gene expression, but knockdown of MYCN by vector-based RNAi as a therapeutic model for neuroblastoma has not been fully established. In this study, we used a lentivirus vector-based RNAi approach which expresses short hairpin RNA (shRNA) to knockdown MYCN in neuroblastoma cell lines IMR-32 and LAN-1. Western blotting analysis showed thatexpressions of MYCN were efficiently downregulated after infection with MYCN shRNA expression vector. The stable suppression of MYCN expression induced differentiation and apoptosis in neuroblastoma cell lines. Furthermore, we demonstrated that these changes were associated with caspase-3 activation, p27 upregulation as well as Bcl-2 and MDM2 downregulation. Finally, we demonstrated that downregulation of MYCN expression significantly reduced colony formation invitro and tumor growth in nude mice. Our data indicate that lentivirus vector-mediated silencing of MYCN in neuroblastoma cells could efficiently and significantly inhibit tumor growth both in vitro and in vivo. Therefore we demonstrate the therapeutic potential of lentivirus-delivered shRNA as a novel approach for treatment of neuroblastoma and other malignant tumors with MYCN overexpression.#CI- Copyright (c) 2011 Elsevier Inc. ALL rights reserved.

Molecular probes were used to characterize an unusual small round cell abdominaltumor arising from the fallopian tube of a 15-year-old girl. DNA and RNA extracted from the tumor and adjacent normal tissue was subjected to Southern and Northern blot analysis using a variety of different probes. N-myc oncogene RNA was greatly expressed in the tumor, but was not expressed in normal tissue or amplified in chromosomal DNA. Insulin-like growth factor II RNA was similarly overexpressed in the neoplasm, but not in normal tissue. While histopathologic studies could not distinguish between a neuroectodermal neoplasm and Wilms' tumor, electron microscopy and the pattern of gene expression was most consistent with Wilms' tumor.

There is a large population of children conceived via assisted reproductive technology (ART), which continues to increase worldwide, without a clear understanding of associated long-term outcomes. ART children are more likely to be the result of multiple pregnancies, and thus to be born prematurely or low birthweight. There is growing evidence that ART children are phenotypically and biochemically different from naturally conceived children, but the mechanism(s) leading to these changes have not been elucidated. There is a possible increasedrisk of rare imprinted gene disorders in these children. However, it remains unclear whether more subtle changes in DNA methylation occur commonly, leading to differences in gene expression and phenotype in ART children. Although an increased risk of cancer among ART children has been reported, the role of ART in the development of cancer has not been demonstrated. Further research and ongoing surveillance of ART children is essential to better understand the possible effects of ART on the long-term health of this population.

Chromosome abnormalities found in pediatric solid tumors include deletions, translocations, homogeneously staining regions (hsr)/double minutes (dms), and ploidy abnormalities. The discovery of a 13q14 deletion found in lymphocytes of patients with retinoblastoma and developmental delay has led to the cloning of the retinoblastoma gene. Likewise the discovery of an 11p13 deletion in lymphocytes of patients with Wilms' tumor and aniridia has led to the cloning ofthe Wilms' tumor gene. Chromosome deletions found in tumor cells are considered to play a role on the homologous deletion of cancer suppressor genes. Recently, various translocations have been found mostly in soft tissue sarcomas; i.e. t(11;22) in Ewing's sarcoma, t(2;13) in alveolar rhabdomyosarcoma, t(3;8) in pleomorphic adenoma, t(3;12) in lipoma, t(12;16) in liposarcoma, t(12;14) in leiomyosarcoma, and t(X;18) in synovial sarcoma. These translocations provide important information on the difficult diagnosis of soft tissue sarcomas, and onthe selection of chemotherapy protocol. tumor cells in advanced stage neuroblastomas often show hsr/dms, in which N-myc amplification occurs. While near triploidy was regularly found in early-stage neuroblastomas, near-diploidy or near-tetraploidy was usually found in advanced stage tumors. Among various prognostic factors, N-myc copy numbers and tumor cell ploidies had the largest influence on the prognosis of neuroblastoma patients. Cytogenetic and molecular genetic analyses on tumor cells are becoming increasingly important for the diagnosis of pediatric solid tumors, and the prediction of the patients' prognosis.

BACKGROUND: Although the prognostic value of the ATP-binding cassette, subfamilyC (ABCC) transporters in childhood neuroblastoma is usually attributed to their role in cytotoxic drug efflux, certain observations have suggested that these multidrug transporters might contribute to the malignant phenotype independent of cytotoxic drug efflux. METHODS: A v-myc myelocytomatosis viral related oncogene,neuroblastoma derived (MYCN)-driven transgenic mouse neuroblastoma model was crossed with an Abcc1-deficient mouse strain (658 hMYCN(1/-), 205 hMYCN(+/1) mice) or, alternatively, treated with the ABCC1 inhibitor, Reversan (n = 20). ABCC genes were suppressed using short interfering RNA or overexpressed by stable transfection in neuroblastoma cell lines BE(2)-C, SH-EP, and SH-SY5Y, which werethen assessed for wound closure ability, clonogenic capacity, morphological differentiation, and cell growth. Real-time quantitative polymerase chain reaction was used to examine the clinical significance of ABCC family gene expression in a large prospectively accrued cohort of patients (n = 209) with primary neuroblastomas. Kaplan-Meier survival analysis and Cox regression were used to test for associations with event-free and overall survival. Except wherenoted, ALL statistical tests were two-sided. RESULTS: Inhibition of ABCC1 statistically significantly inhibited neuroblastoma development in hMYCN transgenic mice (mean age for palpable tumor: treated mice, 47.2 days; control mice, 41.9 days; hazard ratio [HR] = 9.3, 95% confidence interval [CI] = 2.65 to32; P < .001). Suppression of ABCC1 in vitro inhibited wound closure (P < .001) and clonogenicity (P = .006); suppression of ABCC4 enhanced morphological differentiation (P < .001) and inhibited cell growth (P < .001). Analysis of 209neuroblastoma patient tumors revealed that, in contrast with ABCC1 and ABCC4, low rather than high ABCC3 expression was associated with reduced event-free survival (HR of recurrence or death = 2.4, 95% CI = 1.4 to 4.2; P = .001), with 23 of 53 patients with low ABCC3 expression experiencing recurrence or death compared with 31 of 155 patients with high ABCC3. Moreover, overexpression of ABCC3 in vitro inhibited neuroblastoma cell migration (P < .001) and clonogenicity (P = .03). The combined expression of ABCC1, ABCC3, and ABCC4 was associated with patients having an adverse event, such that of the 12 patients with the "poor prognosis" expression pattern, 10 experienced recurrence or death (HR of recurrence or death = 12.3, 95% CI = 6 to 27; P < .001). CONCLUSION: ABCC transporters can affect neuroblastoma biology independently of their role in chemotherapeutic drug efflux, enhancing their potential as targets for therapeutic intervention.

childhood neuroblastoma exhibits a heterogeneous clinical behavior ranging from low-risk tumors with the ability to spontaneously differentiate and regress, to high-risk tumors causing the highest number of cancer related deaths in infants.Amplification of the MYCN oncogene is one of the few prediction markers for adverse outcome. This gene encodes the MYCN transcriptional regulator predominantly expressed in the developing peripheral neural crest. MYCN is vitalfor proliferation, migration and stem cell homeostasis while decreased levels are associated with terminal neuronal differentiation. Interestingly, high-risk tumors without MYCN amplification frequently display increased c-MYC expression and/or activation of MYC signaling pathways. On the other hand, downregulation of MYCN leads to decreased proliferation and differentiation, emphasizing the importance of MYC signaling in neuroblastoma biology. Furthermore, expression ofthe neurotrophin receptor TrkA is associated with good prognosis, the ability todifferentiate and spontaneous regression while expression of the related TrkB receptor is correlated with bad prognosis and MYCN amplification. Here we discuss the role of MYCN in neuroblastoma with a special focus on the contribution of elevated MYCN signaling for an aggressive and undifferentiated phenotype as wellas the potential of using MYCN as a therapeutic target.#CI- Copyright A(c) 2011 Elsevier Ltd. ALL rights reserved.

BACKGROUND: Neuroblastoma (NB) is an aggressive tumor of childhood with a highlyheterogeneous course. Identification of standard prognostic factors has several limitations. Hence, there is an increasing demand to identify new prognostic factors and tools that help in risk stratification of patients for proper treatment. OBJECTIVE: To assess the prognostic and predictive impact of quantitative telomerase expression in NB patients. METHODS: We investigated quantitative telomerase expression by immunohistochemistry in 44 neuroblastoma patients. Results were correlated with standard prognostic factors, n-myc amplification by chromogen in situ hybridization (CISH) and patients' response to treatment and survival. RESULTS: High telomerase expression and n-myc expressionwere reported in 52.3% and 56.8% ; respectively. There was a significant relation between telomerase expression and n-myc amplification. Stage 3 and 4 represented91% of patients. Thirteen patients showed complete remission, 9 partial remission, 19 no response and 3 showed progressive disease. The median followup was 3 years with 80% overall and 72% progression free survival for the low teleomerase expression group; and 52.2% and 55.4% for high teleomerase expression group. High Telomerase expression by immunohistochemistry was significantly associated with n-myc amplification and with poor response to treatment with a trend toward lower overall and progression free survival. CONCLUSIONS: Telomerase expression by immunohistochemistry is a simple potential tool for risk stratification of NB patients. CISH can serve as a readily available alternativesimple tool, compared to FISH, in identifying neuroblastoma cases with abnormal n-myc gene copy number. KEY WORDS: Telomerase expression- N-myc amplification- Prognosis- Neuroblastoma.

Neuroblastoma is the most common extracranial tumor of childhood. The clinical behavior is variable, ranging from spontaneous regression to fatal progression despite aggressive therapy. The most highly statistically significant and clinically relevant factors that are currently used for classification include stage, age, histopathologic category, MYCN oncogene status, chromosome 11q status and DNA ploidy. These genetic markers were analyzed separately by classical methods until recently: mainly fluorescence in situ hybridization or loss of heterozygosity. The development of genome-wide techniques such as comparative genomic hybridization, array comparative genomic hybridization and single nucleotide polymorphism allows the analysis of copy number variations through the whole genome in one step. This enabled the investigators to refine different genetic subtypes for the better comprehension of neuroblastoma tumor behavior and reach the conclusion that these data together with a genomic profile based on gene expression should be included in future treatment stratification.

BACKGROUND: Wilms tumor (WT) is one of the most common malignancies in childhood. With current therapy protocols up to 90% of patients can be cured, but there is still a need to improve therapy for patients with aggressive WT and to reduce treatment intensity where possible. Prior data suggested a deregulation of the retinoic acid (RA) signaling pathway in high-risk WT, but its mode of action remained unclear. RESULTS: The association of retinoid signaling and clinical parameters could be validated in a large independent tumor set, but its relevance in primary nephrectomy tumors from very young children may be different. ReducedRA pathway activity and MYCN overexpression were found in high risk tumors as opposed to tumors with low/intermediate risk, suggesting a beneficial impact of RA especially on advanced WT. To search for possible modes of action of retinoids as novel therapeutic options, primary tumor cell cultures were treated in vitro with all-trans-RA (ATRA), 9cis-RA, fenretinide and combinations of retinoids anda histone deacetylase (HDAC) inhibitor. Genes deregulated in high risk tumors showed opposite changes upon treatment suggesting a positive effect of retinoids. 6/7 primary cultures tested reduced proliferation, irrespective of prior RA signaling levels. The only variant culture was derived from mesoblastic nephroma, a distinct childhood kidney neoplasm. Retinoid/HDAC inhibitor combinations provided no synergistic effect. ATRA and 9cis-RA induced morphological changes suggestive of differentiation, while fenretinide induced apoptosis in several cultures tested. Microarray analysis of ATRA treated WT cells revealed differential expression of many genes involved in extracellular matrix formationand osteogenic, neuronal or muscle differentiation. The effects documented appear to be reversible upon drug withdrawal, however. CONCLUSIONS: Altered retinoic acid signaling has been validated especially in high risk Wilms tumors. In vitrotesting of primary tumor cultures provided clear evidence of a potential utilityof retinoids in Wilms tumor treatment based on the analysis of gene expression, proliferation, differentiation and apoptosis.

pediatric medulloblastoma is considered a highly heterogeneous disease and a newstrategy of risk stratification to optimize therapeutic outcomes is required. Weaimed to investigate a new risk-stratification approach based on expression profiles of medulloblastoma cohorts. We analyzed gene expression profiles of 30 primary medulloblastomas and detected strong evidence that poor survival outcomewas significantly associated with mRNA expression profiles of 17p loss. However,it was not supported in independent cohorts from previously published data (n = 100). We speculated that this discrepancy might come from complex conditions of two important prognostic determinants: loss of tumor suppressors (chromosome 17p) and high expression of oncogenes c-myc (MYCC) or N-myc (MYCN). When patients were stratified into 5 or 7 subgroups based on simultaneous consideration of these 2 factors while defining the Wnt group as independent, obviously different survival expectancies were detected between the subgroups. For instance, predicted 5-yearsurvival probabilities ranged from 19% to 81% in the 5 subgroups. We also found that age became a significant prognostic marker after adjusting for 17p, MYCC, and MYCN status. Diminished survival in age <3 years was more substantial in subgroups with high expression of MYCC, MYCN, or 17p loss but not in other subgroups, indicating that poor survival outcome might be synergistically affected by these 3 factors. Here we suggest a more tailored subgrouping system based on expression profiles of chromosome 17p, MYCC, and MYCN, which could provide the basis for a novel risk-stratification strategy in pediatric medulloblastoma.

Focal high-level amplifications of MYC (or MYCC) define a subset of high-risk medulloblastoma patients. However, the prognostic role of MYCN oncogene amplification remains unresolved. We aimed to evaluate the prognostic value of this alteration alone and in combination with biological modifiers in 67 pediatric medulloblastomas with MYCN amplification (MYCN-MB). Twenty-one MYCN-MBwere examined using gene expression profiling and array-CGH, whereas for 46 tumors immunohistochemical analysis and FISH were performed. ALL 67 tumors were further subjected to mutational analyses. We compared molecular, clinical, and prognostic characteristics both within biological MYCN-MB groups and with non-amplified tumors. Transcriptomic analysis revealed SHH-driven tumorigenesis in a subset of MYCN-MBs indicating a biological dichotomy of MYCN-MB. Activationof SHH was accompanied by variant-specific cytogenetic aberrations including deletion of 9q in SHH tumors. Non-SHH MB were associated with gain of 7q and isochromosome 17q/17q gain. Among clinically relevant variables, SHH subtype and10q loss for non-SHH tumors comprised the most powerful markers of favorable prognosis in MYCN-MB. In conclusion, we demonstrate considerable heterogeneity within MYCN-MB in terms of genetics, tumor biology, and clinical outcome. Thus, assessment of disease group and 10q copy-number status may improve risk stratification of this group and may delineate MYCN-MB with the same dismal prognosis as MYC amplified tumors. Furthermore, based on the enrichment of MYCN and GLI2 amplifications in SHH-driven medulloblastoma, amplification of these downstream signaling intermediates should be taken into account before a patientis enrolled into a clinical trial using a smoothened inhibitor.

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.

BACKGROUND: Protein tyrosine phosphatase receptor delta (PTPRD) is a member of alarge family of protein tyrosine phosphatases which negatively regulate tyrosinephosphorylation. Neuroblastoma is a major childhood cancer arising from precursor cells of the sympathetic nervous system which is known to acquire deletions and alterations in the expression patterns of PTPRD, indicating a potential tumor suppressor function for this gene. The molecular mechanism, however, by which PTPRD renders a tumor suppressor effect in neuroblastoma is unknown. RESULTS: Asa molecular mechanism, we demonstrate that PTPRD interacts with aurora kinase A (AURKA), an oncogenic protein that is over-expressed in multiple forms of cancer, including neuroblastoma. Ectopic up-regulation of PTPRD in neuroblastoma dephosphorylates tyrosine residues in AURKA resulting in a destabilization of this protein culminating in interfering with one of AURKA's primary functions inneuroblastoma, the stabilization of MYCN protein, the gene of which is amplifiedin approximately 25 to 30% of high risk neuroblastoma. CONCLUSIONS: PTPRD has a tumor suppressor function in neuroblastoma through AURKA dephosphorylation and destabilization and a downstream destabilization of MYCN protein, representing anovel mechanism for the function of PTPRD in neuroblastoma.

Neuroblastoma is the most common cancer in childhood. The majority of patients with neuroblastoma are assigned to the high-risk group based on age at diagnosis, stage, histology, MYCN status, and DNA ploidy. Their prognosis remains unsatisfactory; the 5-year event-free survival (EFS) rate is generally 40 %. During the past 20 years, much effort has been made to reinforce chemotherapy, including the introduction of high-dose chemotherapy with autologous stem cell rescue, resulting in a 5-year EFS rate of around 30 %. Subsequently, maintenancetherapy aimed at eradicating residual tumors after induction and consolidation therapies was introduced, consisting of differentiation-inducing agents, retinoids, and immunotherapy using anti-GD2 antibodies combined with cytokines. However, such additional treatment provided benefit to only 10-20 % of patients,while the prognosis of about half the patients remains poor. Currently, novel targeted agents are under development. Among them, anaplastic lymphoma kinase (ALK) inhibitors and aurora kinase A inhibitors are promising. ALK somatic mutation or gene amplification predisposing neuroblastoma development occurs in up to 15 % of neuroblastomas. Crizotinib is a dual-specific inhibitor of ALK/Metand inhibits proliferation of neuroblastoma cells harboring R1275Q-mutated ALK or amplified wild-type ALK, but not cells harboring F1174L. Instead, cells with F1174L are sensitive to another small molecule ALK inhibitor, TAE684. Aurora kinase A plays a pivotal role in centrosome maturation and spindle formation during mitosis. MLN8237 (alisertib) is a small molecule inhibitor of aurora kinase A that is currently in early-phase clinical testing. Future treatment will be individually planned, adapting targeted agents based on personal biological tumor characteristics.

Neuroblastoma is a pediatric tumor of the sympathetic nervous system. MYCN (V-myc myelocytomatosis viral-related oncogene, neuroblastoma derived [avian]) is amplified in 20% of neuroblastomas, and these tumors carry a poor prognosis. However, tumors without MYCN amplification also may have a poor outcome. Here, we identified downstream targets of MYCN by shRNA-mediated silencing MYCN in neuroblastoma cells. From these targets, 157 genes showed an expression profile correlating with MYCN mRNA levels in NB88, a series of 88 neuroblastoma tumors, and therefore represent in vivo relevant MYCN pathway genes. This 157-gene signature identified very poor prognosis tumors in NB88 and independent neuroblastoma cohorts and was more powerful than MYCN amplification or MYCN expression alone. Remarkably, this signature also identified poor outcome of a group of tumors without MYCN amplification. Most of these tumors have low MYCN mRNA levels but high nuclear MYCN protein levels, suggesting stabilization of MYCN at the protein level. One tumor has an MYC amplification and high MYC expression. Chip-on-chip analyses showed that most genes in this signature are directly regulated by MYCN. MYCN induces genes functioning in cell cycle and DNArepair while repressing neuronal differentiation genes. The functional MYCN-157 signature recognizes classical neuroblastoma with MYCN amplification, as well asa newly identified group marked by MYCN protein stabilization.

Midkine is a heparin-binding growth factor highly expressed in various cancers, including neuroblastoma, the most common extracranial pediatric solid tumor. Prognosis of patients with neuroblastoma in which MYCN is amplified remains particularly poor. In this study, we used a MYCN transgenic model for neuroblastoma in which midkine is highly expressed in precancerous lesions of sympathetic ganglia. Genetic ablation of midkine in this model delayed tumor formation and reduced tumor incidence. Furthermore, an RNA aptamer that specifically bound midkine suppressed the growth of neuroblastoma cells in vitroand in vivo in tumor xenografts. In precancerous lesions, midkine-deficient MYCNtransgenic mice exhibited defects in activation of Notch2, a candidate midkine receptor, and expression of the Notch target gene HES1. Similarly, RNA aptamer-treated tumor xenografts also showed attenuation of Notch2-HES1 signaling. Our findings establish a critical role for the midkine-Notch2 signaling axis in neuroblastoma tumorigenesis, which implicates new strategies to treat neuroblastoma.

BACKGROUND: Amplification of MYCN oncogene is an established marker indicating aggressive tumor progression of neuroblastoma (NBL). But copy number analyses ofMYCN gene in ganglioneuroblastoma (GNBL) and ganglioneuroma(GN) is poorly described in the literature. In the study, we evaluated the copy number aberrations of MYCN gene in clinical samples of NBLs, GNBLs and GNs and analyzedtheir association with clinical outcome of the patients. METHODS: In this study,we analyzed MYCN gene and chromosome 2 aneusomy by using fluorescence in situ hybridization (FISH) method in a total of 220 patients with NBL, GNBL and GN cases. Kaplan-Meier curves were generated by using SPSS 12.0 software. RESULTS: Of 220 patients, 178 (81.0%) were NBLs, 32 (14.5%) were GNBLs and 10 (4.5%) wereGNs. MYCN gain is a recurrent genetic aberration of neuroblastic tumors (71.8%, 158/220), which was found in 129 NBLs (58.6%, 129/220), 25 GNBLs (11.4%, 25/220)and 4 GN cases (1.8%, 4/220). However, MYCN amplification was only present in 24NBL tumors (13.5%, 24/178) and 1 GNBL case (3.1%, 1/32). Kaplan-Meier survival analysis indicated that MYCN amplification is significantly correlated with decreased overall survival in NBLs (P=0.017). Furthermore, a better prognosis trend was observed in patients with MYCN gain tumors compared with those with MYCN gene normal copy number tumors and MYCN amplification tumors (P=0.012). CONCLUSIONS: In summary, the frequency of MYCN amplification in NBLs is high andis rarely observed in GNBLs and GNs, which suggest MYCN plays an important role in neuroblastic tumors differentiation. MYCN gain appeared to define a subgroup of NBLs with much better outcome and classification of MYCN gene copy number alteration as three groups (amplification, gain and normal) can provide a powerful prognostic indicator in NBLs. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/6417541528559124.

pediatric glioblastomas recently have been exon sequenced with evidence that approximately 30 % of cases harbour mutations of the histone H3.3 gene. Althoughstudies to determinate their role in risk stratification are on-going, it remains to be determined whether H3.3 mutations could be found in other tumors such as pediatric primitive neuroectodermal tumors of the central nervous system (CNS-PNETs) and whether the presence of H3.3 mutations in glioblastomas could beused as diagnostic tool in their differential diagnosis with CNS-PNETs. We performed a large mutational pyrosequencing-based screening on 123 pediatric glioblastomas and 33 CNS-PNET. The analysis revealed that 39/123 (31.7 %) glioblastomas carry H3.3 mutations. The K27M (AAG --> ATG, lysine --> methionine) mutation was found in 33 glioblastomas (26 %); the G34R (GGG --> AGG, glycine --> arginine) was observed in 6 glioblastomas (5.5 %). However, we also identified 4of 33 cases (11 %) of CNS-PNETs harbouring a H3.3 G34R mutation. Multiplex ligation-dependent probe amplification analysis revealed PDGFR-alpha amplification and EGFR gain in two cases and N-Myc amplification in one case of H3.3 G34R mutated CNS-PNET. None of H3.3 mutated tumors presented a CDKN2A loss.In conclusion, because pediatric patients with glioblastoma and CNS-PNET are treated according to different therapeutic protocols, these findings may raise further concerns about the reliability of the histological diagnosis in the caseof an undifferentiated brain tumor harbouring G34R H3.3 mutation. In this view, additional studies are needed to determine whether H3.3 G34 mutated CNS-PNET/glioblastomas may represent a defined tumor subtype.

Neuroblastoma is the most common solid tumor of infancy, and mutations in several genes have been implicated as playing a role in tumor development. Here, we describe a pediatric patient with a constitutional microduplication of 2p24.3 who developed Stage 4 neuroblastoma at age 11 months. He represents the sixth patient described in the literature with partial trisomy 2p and neuroblastoma. ALL previous cases had duplication events spanning two genes implicated in neuroblastoma, MYCN and ALK. Our patient is unique because his duplicated regionincludes the MYCN gene only; the ALK gene is unaffected. These data, combined with the relatively high incidence of neuroblastoma reported in partial trisomy 2p patients, support the notion that MYCN duplication should be added to the growing list of genetic factors associated with an increased risk of neuroblastoma. The mechanism of increased risk is unclear, but the fact that ourpatient had dramatic amplification of MYCN in his tumor suggests that a germlineduplication might predispose to further amplification. Additionally, our patienthas several morphologic features common to patients with partial trisomy 2p including high forehead, hypertelorism, postaxial polydactyly, and developmentaldelay despite having a microduplication spanning approximately 1 Mb and including just three intact genes. This case may therefore help further delineate the genotype-phenotype correlations associated with partial trisomy 2p.#CI- Copyright (c) 2013 Wiley Periodicals, Inc.

Neuroblastoma (NB) is the most common extracranial pediatric tumor. NB patients over 18 months of age at the time of diagnosis are often in the later stages of the disease, present with widespread dissemination, and often possess MYCN tumorgene amplification. MYCN is a transcription factor that regulates the expressionof a number of genes including ornithine decarboxylase (ODC), a rate-limiting enzyme in the biosynthesis of polyamines. Inhibiting ODC in NB cells produces many deleterious effects including G(1) cell cycle arrest, inhibition of cell proliferation, and decreased tumor growth, making ODC a promising target for drug interference. DFMO treatment leads to the accumulation of the cyclin-dependent kinase inhibitor p27(Kip1) protein and causes p27(Kip1)/Rb-coupled G(1) cell cycle arrest in MYCN-amplified NB tumor cells through a process that involves p27(Kip1) phosphorylation at residues Ser10 and Thr198. While p27(Kip1) is well known for its role as a cyclin-dependent kinase inhibitor, recent studies have revealed a novel function of p27(Kip1) as a regulator of cell migration and invasion. In the present study we found that p27(Kip1) regulates the migration and invasion in NB and that these events are dependent on the state of phosphorylation of p27(Kip1). DFMO treatments induced MYCN protein downregulation and phosphorylation of Akt/PKB (Ser473) and GSK3-beta (Ser9), and polyamine supplementation alleviated the DFMO-induced effects. Importantly, we provide strong evidence that p27(Kip1) mRNA correlates with clinical features and the survival probability of NB patients.

BACKGROUND: Retinoblastoma is the childhood retinal cancer that defined tumour-suppressor genes. Previous work shows that mutation of both alleles of the RB1 retinoblastoma suppressor gene initiates disease. We aimed to characterise non-familial retinoblastoma tumours with no detectable RB1 mutations. METHODS: Of 1068 unilateral non-familial retinoblastoma tumours, we compared those with no evidence of RB1 mutations (RB1(+/+)) with tumours carrying a mutation in both alleles (RB1(-/-)). We analysed genomic copy number, RB1 gene expression and protein function, retinal gene expression, histological features, and clinical data. FINDINGS: No RB1 mutations (RB1(+/+)) were reported in 29 (2.7%) of 1068 unilateral retinoblastoma tumours. 15 of the 29 RB1(+/+) tumours had high-level MYCN oncogene amplification (28-121 copies; RB1(+/+)MYCN(A)), whereas none of 93RB1(-/-) primary tumours tested showed MYCN amplification (p<0.0001). RB1(+/+)MYCN(A) tumours expressed functional RB1 protein, had fewer overall genomic copy-number changes in genes characteristic of retinoblastoma than did RB1(-/-) tumours, and showed distinct aggressive histological features. MYCN amplification was the sole copy-number change in one RB1(+/+)MYCN(A) retinoblastoma. One additional MYCN(A) tumour was discovered after the initial frequencies were determined, and this is included in further analyses. Median age at diagnosis of the 17 children with RB1(+/+)MYCN(A) tumours was 4.5 months (IQR3.5-10), compared with 24 months (15-37) for 79 children with non-familial unilateral RB1(-/-) retinoblastoma. INTERPRETATION: Amplification of the MYCN oncogene might initiate retinoblastoma in the presence of non-mutated RB1 genes.These unilateral RB1(+/+)MYCN(A) retinoblastomas are characterised by distinct histological features, only a few of the genomic copy-number changes that are characteristic of retinoblastoma, and very early age of diagnosis. FUNDING: National cancer Institute-National Institutes of Health, Canadian Institutes of Health Research, German Research Foundation, Canadian Retinoblastoma Society, Hyland Foundation, Toronto Netralaya and Doctors Lions Clubs, Ontario Ministry of Health and Long Term Care, UK-Essen, and Foundations Avanti-STR and KiKa.#CI- Copyright (c) 2013 Elsevier Ltd. ALL rights reserved.

Neuroblastoma, the most common extracranial pediatric solid tumor, is responsible for 15% of ALL childhood cancer deaths. Patients frequently present at diagnosiswith metastatic disease, particularly to the bone marrow. Advances in therapy and understanding of the metastatic process have been limited due, in part, to the lack of animal models harboring bone marrow disease. The widely used transgenic model, the Th-MYCN mouse, exhibits limited metastasis to this site. Here, we establish the first genetic immunocompetent mouse model for metastatic neuroblastoma with enhanced secondary tumors in the bone marrow. This model recapitulates 2 frequent alterations in metastatic neuroblasoma, overexpression of MYCN and loss of caspase-8 expression. Mouse caspase-8 gene was deleted in neural crest lineage cells by crossing a Th-Cre transgenic mouse with a caspase-8 conditional knockout mouse. This mouse was then crossed with the neuroblastoma prone Th-MYCN mouse. Although overexpression of MYCN by itself rarely caused bone marrow metastasis, combining MYCN overexpression and caspase-8 deletion significantly enhanced bone marrow metastasis (37% incidence). Microarray expression studies of the primary tumors mRNAs and microRNAs revealed extracellular matrix structural changes, increased expression of genes involved in epithelial to mesenchymal transition, inflammation, and downregulation of miR-7a and miR-29b. These molecular changes have been shown to be associated with tumor progression and activation of the cytokine TGF-beta pathway in various tumor models. Cytokine TGF-beta can preferentially promote single cell motility and blood-borne metastasis and therefore activation of this pathway may explain the enhanced bone marrow metastasis observed in this animal model. cancer Res; 73(13); 4086-97. (c)2013 AACR.

Neuroblastoma is a tumor accounting for approximately 10% of ALL childhood malignancies and 50% of ALL childhood cancer-related deaths. MYCN gene copy number variation represents the most important prognostic factor in neuroblastoma. Prognostic significance of MYCN gene expression is more complicated and may depend on other factors such as MYCN gene copy number status. In the present study, we assessed MYCN gene expression using real-time RT-PCR following cisplatin treatment in three human neuroblastoma cell lines (UKF-NB-3,UKF-NB-4 and SK-N-AS) and their cisplatin-resistant counterparts. We also examined MYCN gene status and copy number (gain and amplification) variations using interphase and metaphase fluorescent in situ hybridization (FISH) and multiplex ligation-dependent probe amplification (MLPA). Only cisplatin-sensitive UKF-NB-4 cells exhibited decreased MYCN expression following treatment with cisplatin. Other sensitive neuroblastoma cells did not exhibit a change in MYCN expression. In contrast, cisplatin-resistant UKF-NB-4 and SK-N-AS cells exhibited increased MYCN expression irrespective of the number of MYCN copies or concentration of cisplatin in the medium. In MYCN-amplified neuroblastoma cells we did not observe any significant change in the number of MYCN copies after cisplatin treatment, whereas MYCN-non-amplified SK-N-AS cells revealed during cisplatin treatment an increased number of MYCN gene copies caused by 2p gain inthe majority of cells by FISH. We postulated that cisplatin treatment does not result directly in altered transcription of MYCN. A functional change in MYCN mRNA levels and increased MYCN expression in cisplatin-resistant neuroblastoma cells do not have a clear relationship to MYCN copy numbers. These findings may further contribute to the understanding of cisplatin chemotherapy in connection with MYCN expression, and the possible copy number variations in MYCN neuroblastoma cells may be of importance since targeting of MYCN is being testedas neuroblastoma therapy.

BACKGROUND: Aggressive neuroblastoma remains a significant cause of childhood cancer death despite current intensive multimodal treatment protocols. The purpose of the present work was to characterize the genetic and clinical diversity of such tumors by high resolution arrayCGH profiling. METHODS: Based on a 32K BAC whole-genome tiling path array and using 50-250K Affymetrix SNP array platforms for verification, DNA copy number profiles were generated for 34 consecutive high-risk or lethal outcome neuroblastomas. In addition, age and MYCN amplification (MNA) status were retrieved for 112 unfavorable neuroblastomas of the Swedish childhood cancer Registry, representing a 25-year neuroblastoma cohort of Sweden, here used for validation of the findings. Statistical tests used were: Fisher's exact test, Bayes moderated t-test, independent samples t-test, and correlation analysis. RESULTS: MNA or segmental 11q loss (11q-) was found in 28/34 tumors. With two exceptions, these aberrations were mutually exclusive. children with MNA tumors were diagnosed at significantly younger agesthan those with 11q- tumors (mean: 27.4 vs. 69.5 months; p=0.008; n=14/12), and MNA tumors had significantly fewer segmental chromosomal aberrations (mean: 5.5 vs. 12.0; p<0.001). Furthermore, in the 11q- tumor group a positive correlation was seen between the number of segmental aberrations and the age at diagnosis (Pearson Correlation 0.606; p=0.037). Among nonMNA/non11q- tumors (n=6), one tumor displayed amplicons on 11q and 12q and three others bore evidence of progression from low-risk tumors due to retrospective evidence of disease six years before diagnosis, or due to tumor profiles with high proportions of numerical chromosomal aberrations. An early age at diagnosis of MNA neuroblastomas was verified by registry data, with an average of 29.2 months for43 cases that were not included in the present study. CONCLUSION: MNA and segmental 11q loss define two major genetic variants of unfavorable neuroblastoma with apparent differences in their pace of tumor evolution and in genomic integrity. Other possible, but less common, routes in the development of aggressive tumors are progression of low-risk infant-type lesions, and gene amplifications other than MYCN. Knowledge on such nosological diversity of aggressive neuroblastoma might influence future strategies for therapy.

BACKGROUND: Neuroblastoma is the most common pediatric solid tumor. About fifty percent of high risk patients die despite treatment making the exploration of new and more effective strategies for improving stratification mandatory. Hypoxia isa condition of low oxygen tension occurring in poorly vascularized areas of the tumor associated with poor prognosis. We had previously defined a robust gene expression signature measuring the hypoxic component of neuroblastoma tumors (NB-hypo) which is a molecular risk factor. We wanted to develop a prognostic classifier of neuroblastoma patients' outcome blending existing knowledge on clinical and molecular risk factors with the prognostic NB-hypo signature. Furthermore, we were interested in classifiers outputting explicit rules that could be easily translated into the clinical setting. RESULTS: Shadow Clustering(SC) technique, which leads to final models called Logic Learning Machine (LLM),exhibits a good accuracy and promises to fulfill the aims of the work. We utilized this algorithm to classify NB-patients on the bases of the following risk factors: Age at diagnosis, INSS stage, MYCN amplification and NB-hypo. The algorithm generated explicit classification rules in good agreement with existing clinical knowledge. Through an iterative procedure we identified and removed from the dataset those examples which caused instability in the rules. This workflow generated a stable classifier very accurate in predicting good and poor outcome patients. The good performance of the classifier was validated in an independentdataset. NB-hypo was an important component of the rules with a strength similarto that of tumor staging. CONCLUSIONS: The novelty of our work is to identify stability, explicit rules and blending of molecular and clinical risk factors asthe key features to generate classification rules for NB patients to be conveyedto the clinic and to be used to design new therapies. We derived, through LLM, aset of four stable rules identifying a new class of poor outcome patients that could benefit from new therapies potentially targeting tumor hypoxia or its consequences.

We studied the expression of the N-myc proto-oncogene and the insulin-like growth factor-II (IGF-II) gene in human fetuses of 16-19 gestational wk. Both genes have specific roles in the growth and differentiation of embryonic tissues, such as the kidney and neural tissue. Since continued expression of N-myc and IGF-II mRNAs is also a characteristic feature of Wilms' tumor, a childhood neoplasm of probable fetal kidney origin, we were particularly interested in the possibilitythat their expression might be linked or coordinately regulated in the developing kidney. expression of N-myc mRNA was observed in the brain and in the kidney by Northern hybridization analysis. In in situ hybridization of the kidney, N-myc autoradiographic grains were primarily located over epithelially differentiatingmesenchyme while most of the mesenchymal stromal cells showed only a background signal with the N-myc probe. N-myc mRNA was detectable throughout the developingbrain with a slight accentuation in the intermediate zone cells in between the subependymal and cortical layers. Thus, even postmitotic neuroepithelial cells of the fetal cerebrum expressed N-myc mRNA. In Northern hybridization, IGF-II mRNA signal was abundant in the kidney but much weaker, though definite, in the brain. The regional distribution of IGF-II mRNA in the kidney was largely complementaryto that of N-myc. IGF-II autoradiographic grains were located predominantly overthe stromal and blastemal cells with a relative lack of hybridization over the epithelial structures. In the brain, IGF-II mRNA was about two- to threefold more abundant in the subependymal and intermediate layers than in the cortical plate and ependymal zone, respectively. The fetal expression patterns of the N-myc andIGF-II mRNAs are reflected by the types of tumors known to express the corresponding genes during postnatal life such as Wilms' tumor. However, the apparent coexpression of the IGF-II and N-myc genes in immature kidneys occurs largely in distinct cell types.

Renal tumors of childhood occasionally exhibit histopathologic and clinical features that preclude accurate diagnosis. Molecular and cell culture techniquesmay be helpful in better characterizing these cases. This approach was used to examine unusual bilateral renal tumors from a young boy. The left kidney tumor was an undifferentiated neoplasm with light microscopic features suggestive of both Wilms' tumor and neuroblastoma, and the right kidney tumor was identified as multilocular cystic nephroma (MLCN). In vitro tissue culture of tumor cells and hybridization experiments with an N-myc oncogene DNA probe contributed to a revised diagnosis of intrarenal neuroblastoma of the left kidney. A cell line established from the left tumor exhibited neurite outgrowth and was positive forneuron-specific enolase and synaptophysin. N-myc was greater than ten-fold amplified in chromosomal DNA from the left kidney tumor. Measurement of N-myc RNA expression enabled distinction between benign and malignant tumor tissue. The detection of N-myc gene amplification predicted a poor prognosis which was confirmed by the patient's subsequent clinical course.

Neuroblastoma is one of the most frequent malignant tumors in childhood. Molecular and cytogenetic methods have led to important advances in our understanding of the biology of this tumor. Amplification and increased expression of the gene N-myc is correlated with the clinical stage. This may be a useful marker for monitoring tumor activity during therapy. In addition, karyotyping and flow cytometric DNA analysis may be useful diagnostic tools for staging and predicting the clinical outcome.

DNA was extracted from formalin-fixed and paraffin-embedded tissues of 85 patients with pediatric malignant solid tumors which had been resected at surgery or obtained at autopsy during a 24-year period. The tumors examined included 25 rhabdomyosarcomas, 12 Wilms' tumors, 10 hepatoblastomas and 37 neuroblastoma group tumors. Neuroblastoma group tumors were subclassified into 25 neuroblastomas and 12 ganglioneuroblastomas among which 6 composite ganglioneuroblastomas were included. Sample blocks were selected from both tumors and normal tissues in the majority of cases. We were able to reliably detect N- and c-myc gene amplification in tumor DNA by dot blot-hybridization. The N-myc gene showed approximately from 3- to 500-fold amplification in 19 of 33 cases ofstage IV neuroblastoma group tumor. ALL of these 33 patients had been intensively treated with chemotherapy and/or radiotherapy. The c-myc was amplified 8-fold in1 case of rhabdomyosarcoma, but neither N-myc nor c-myc was amplified in any cases of Wilms' tumor or hepatoblastoma. We retrospectively examined the association among N-myc gene amplification, prognosis, and histologic subtype in33 patients with stage IV neuroblastoma group tumors. The survival of the patients with N-myc gene amplification was shorter than that of the patients without amplification of N-myc (p less than 0.05). There was no significant difference in prognosis between the 2 histologic subtypes; neuroblastoma and ganglioneuroblastoma, and the cases of tumors with amplified N-myc showed shorter survivals for each subtype (p less than 0.05). In every case of neuroblastoma group tumor, the copy number of the N-myc gene was the same among primary site and multiple metastatic tumors, even when the lesions showed differences in histologic subtype like neuroblastoma and ganglioneuroblastoma.

Malignancies of childhood include a well-defined spectrum of hematolymphoid, organ specific (adrenal, kidney, liver), soft tissue, bone, and nervous system (central and peripheral) neoplasms with variable biology. Small round cell neoplasms, a subset of childhood malignancies, are histologically similar but differ markedly in their histogenesis, therapy, and prognosis. Traditionally, clinical information and light microscopy, with the aid of histochemistry and ultrastructural evaluation, establish a diagnosis or at least narrow the differential diagnosis. Additionally, immunohistology, cytogenetics, and molecular studies have become important in diagnosis and in defining phenotype/genotype, patient treatment modalities, and prognosis in specific cases. The 11;22 chromosomal translocation typifies Ewing's sarcoma, primitive neuroectodermal tumor, and Askin's tumor, as does the resultant chimeric transcript, while expression and amplification of N-myc oncogene are predictive of the prognosis in neuroblastoma. Furthermore, studies of genes and gene products are elucidating mechanisms of oncogenesis and tumor progression.

The MRP gene (Cole et al., Science (Washington DC), 258: 1650-1654, 1992) encodes a membrane-bound glycoprotein the expression of which correlates with non-P-glycoprotein-mediated multidrug resistance in a variety of cultured human cell lines. Using an RNA-polymerase chain reaction assay, expression of this gene was examined in the highly chemoresistant pediatric malignancy, neuroblastoma. MRP expression was observed in 5 human neuroblastoma cell lines and in ALL 25 primary neuroblastoma tumors of stage I through IVS. tumors with amplification of the N-myc oncogene were found to have significantly higher MRP expression that those with no amplification (P = 0.0016). expression of the MRP gene in the tumor specimens was highly correlated with expression of the N-myc gene (P = 0.0009), while expression of the MDR1 gene, encoding P-glycoprotein, was not related to expression of either the N-myc or MRP genes. Decreased expression of the N-myc oncogene in neuroblastoma cell lines SH-SY5Y and BE(2)-C, following treatment with retinoic acid, was paralleled by down-regulation of MRP gene expression, contrasting with increased expression of the MDR1 gene. expression of the MRP gene is thus common in both primary neuroblastoma tumors and cultured cell lines, and correlates with amplification and overexpression of the N-myc oncogene, which is central to the malignant phenotype of this disease.

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.

Oncogenes are genes associated with causation of cancer. They were originally associated with the ability of retroviruses to cause tumors in animals. These viral oncogenes (V-onc) have their cellular counterparts (C-onc) called Proto oncogenes. Function of Proto oncogenes is to maintain cellular growth and development. Activation of these proto-oncogenes can occur due to mutation whichleads to uncontrolled cell growth. The Proto oncogenes can be grouped into different categories based on their protein products, i.e. protein kinases, growth factors, growth factor receptors, and DNA binding proteins. There are also genes that normally suppress malignant transformation and these are called anti oncogenes. Loss of their suppressor activity leads to unimpeded growth. Oncogeneabnormalities are seen in pediatric leukemias, lymphomas, and various solid tumors. Anti oncogenes are associated with retinoblastoma (Rb gene), Wilms' tumor, rhabdomyosarcoma and neuroblastoma, etc. Identification of these abnormalities have diagnostic, prognostic and therapeutic implications. The utility of oncogenes in classification of human cancer and monitoring cancer therapy is quite clear, but the future of these for therapeutic interventions remains uncertain. Role of c-abl oncogene in chronic myeloid leukemia (CML), bcl-2, in lymphomas, N-myc in neuroblastomas and retinoblastoma (Rb) gene in retinoblastomas is well understood and used in designing proper therapeutic approaches. Since oncogenes also control normal cellular function, their use fortherapy may be limited by the amount of damage to normal cells. Their maximum therapeutic benefit may be realized only when used in combination with other modalities.

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.

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.

PURPOSE: In contrast to other human tumors, a repression of the cell-surface glycoprotein CD44 on neuroblastoma is a marker of aggressiveness that usually correlates to N-myc amplification. We thus compared the prognostic value of bothmarkers in the initial staging of 121 children treated for neuroblastoma in collaborative institutions. METHODS: Frozen samples were analyzed by a rapid andwell-standardized technique of immunostaining with monoclonal antibodies (MoAbs)against epitopes in the CD44 constant region. RESULTS: In this retrospective series, CD44 was expressed on 102 specimens and strongly correlated with favorable tumor stages and histology, younger age, and normal N-myc copy numbers. In univariate analysis, CD44 expression and normal N-myc were the most powerful markers of favorable clinical outcome (P < 10(-6) and chi 2 = 65.40 and P < 10(-6) and chi 2 = 42.56, respectively), but analysis of CD44 affords significant prognostic discrimination in subgroups of patients with or without N-myc-amplified tumors. In the subgroup of stage IV neuroblastomas, CD44 was theonly significant prognostic marker (P < .02, chi 2 = 5.76), whereas N-myc statuswas not discriminant. In multivariate analysis of five factors, ie, N-myc amplification, CD44 expression, age, tumor stage, and histology, the only independent prognostic factors of event-free survival were CD44 expression and tumor stage. CONCLUSION: The analysis of CD44 cell-surface expression must be recommended as an additional biologic marker in the initial staging of the disease.

MYCN gene amplification is strongly correlated with poor prognosis in neuroblastoma (NB), the second most common solid pediatric tumor. However, increased MYCN expression seen in tumors that lack MYCN amplification does not correlate with aggressive clinical behavior. Whereas the MYCN gene spans only 7 kb, the MYCN amplicon has been shown to range in size from 350 kb to more than 1Mb. Given the large size of the amplicon, it is possible that additional genes are co-amplified in NBs whose expression may contribute to the aggressive phenotype associated with MYCN-amplified tumors. We isolated a cDNA clone from ahuman NB library that is identical to DDXI, a gene recently reported to be preferentially expressed in two retinoblastoma cell lines that also express highlevels of MYCN. DDXI belongs to a family of genes that encode DEAD (Asp-Glu-Ala-Asp) box proteins, putative ATP-dependent RNA helicases implicated in a number of cellular processes involving alterations of RNA secondary structure. We examined the frequency of DDXI amplification in 15 NB cell lines, 1 neuroepithelioma cell line, and 122 NB tumors by Southern blot analyses, and we found that 7 of 10 MYCN-amplified cell lines and 27 of 40 (68%) MYCN-amplified tumors also harbored multiple copies of the DDXI gene. Amplification of DDXI wasassociated with high levels of DDXI mRNA expression in the NB cell lines and tumors as examined by Northern analysis. Neither DDXI gene amplification nor enhanced expression was observed in tumors or cell lines that lacked MYCN amplification. Because RNA helicases play important roles in both post-transcriptional and translational gene regulation, high levels of DDXI expression consequent to genomic amplification may contribute to the malignant phenotype of a subset of NBs.

Neuroblastoma (NB) is a childhood cancer of the autonomic nervous system. The molecular pathology of NB is not yet well understood. Both amplification of the proto-oncogene N-myc and loss of heterozygosity of several chromosomal loci occur in NB, representing genetic instability. In this study, we examined another typeof genetic instability, microsatellite instability. Five chromosomal loci known to exhibit this alteration in colon, gastric, and pancreatic cancers were used in a PCR-based assay to examine 30 matched normal and tumor DNAs, which included ALL stages of tumor progression. Among these 30, only 2 (7%) manifested microsatellite instability. There was no correlation between the occurrence of microsatellite instability and the amplification of the N-myc gene. These data show that microsatellite instability is infrequent in neuroblastoma tumors.

Conventional cytogenetic analysis of solid tumors is technically very demanding and requires a large number of viable cells. The technique of comparative genomic hybridization (CGH) circumvents these difficulties and has been shown to be particularly useful for identifying new gene amplifications. We have simplified the CGH technique for the detection of amplifications by utilizing a single labeling approach in which labeled tumor DNA is mixed with unlabeled normal human DNA and hybridized to normal metaphases on a slide. To examine the consistency and sensitivity of the method, initial experiments were performed using a retinoblastoma (RB) cell line and five pediatric solid tumors known to contain an amplification. The technique was easy to use and sensitive enough to detect low-level amplifications. The RB cell line showed reproducible signals at 2p24, indicative of amplified sequences, on both homologues in 95% of the metaphases (> 30) examined. Amplifications of the MYCN gene (2p24) were detected in three alveolar rhabdomyosarcomas and one medulloblastoma. CGH was then applied to six tumors in a prospective fashion, before data about specific gene amplification were available. In two, amplification of the MDM2 gene (12q13-14) was identifiedusing CGH and later confirmed by Southern blot analysis. Four tumors negative for MDM2 and MYCN amplifications by CGH analysis were also negative by Southern blotanalysis. Gene amplification as low as fourfold was detected in one tumor and the overall pattern of gene amplification detected by CGH in these tumors was not complex, involving just one amplification site for each case. Therefore, this simplified CGH technique is suitable for routine screening of pediatric solid tumors for amplifications when genetic studies are important but sample sizes are small and dividing cells are infrequent or unavailable.

Conventional cytogenetic analysis of solid tumors is technically very demanding and requires a large number of viable cells. The technique of comparative genomic hybridization (CGH) circumvents these difficulties and has been shown to be particularly useful for identifying new gene amplifications. We have simplified the CGH technique for the detection of amplifications by utilizing a single labeling approach in which labeled tumor DNA is mixed with unlabeled normal human DNA and hybridized to normal metaphases on a slide. To examine the consistency and sensitivity of the method, initial experiments were performed using a retinoblastoma (RB) cell line and five pediatric solid tumors known to contain an amplification. The technique was easy to use and sensitive enough to detect low-level amplifications. The RB cell line showed reproducible signals at 2p24, indicative of amplified sequences, on both homologues in 95% of the metaphases (> 30) examined. Amplifications of the MYCN gene (2p24) were detected in three alveolar rhabdomyosarcomas and one medulloblastoma. CGH was then applied to six tumors in a prospective fashion, before data about specific gene amplification were available. In two, amplification of the MDM2 gene (12q13-14) was identifiedusing CGH and later confirmed by Southern blot analysis. Four tumors negative for MDM2 and MYCN amplifications by CGH analysis were also negative by Southern blotanalysis. Gene amplification as low as fourfold was detected in one tumor and the overall pattern of gene amplification detected by CGH in these tumors was not complex, involving just one amplification site for each case. Therefore, this simplified CGH technique is suitable for routine screening of pediatric solid tumors for amplifications when genetic studies are important but sample sizes are small and dividing cells are infrequent or unavailable.

All-trans-retinoic acid (RA) has been used to suppress growth of malignant cellsand induce epithelial differentiation. We investigated whether RA had a similar effect on Wilms' tumor, a childhood tumor of the kidney that arises from the undifferentiated metanephric blastema. W13 cells, a cell line derived from a blastemal Wilms' tumor, were exposed to RA (10(-9)-10(-5) M) and its effects on cell proliferation, gene expression, and differentiation were examined. Treatment of W13 cells with RA resulted in a dose-dependent suppression of growth. Changesin expression of selected genes were determined by Northern analysis. After 24 h, there was a marked dose-dependent down-regulation of N-myc mRNA as well as up-regulation of insulin-like growth factor-II (IGF-II) mRNA. [125I]IGF-II ligand blotting of conditioned medium from RA-treated cultures revealed a dramatic alteration in the pattern of expression of insulin-like growth factor binding proteins (IGFBPs). Examination of RA-treated W13 cultures by light and electron microscopy did not reveal appreciable morphological changes. We conclude that RAinhibits growth and alters gene expression of W13 cells without inducing epithelial differentiation. The modulation of expression of IGF-II, IGFBP, and N-myc may play a role in RA-induced growth suppression of Wilms' tumor cells.

BACKGROUND: Current staging systems for unresectable or metastatic neuroblastomado not reliably predict responses to chemotherapy in infants under 1 year of age. Previous studies have indicated that the DNA content, or ploidy, of malignant neuroblasts can discriminate between good and poor responders in this group of patients, but the clinical utility of ploidy assessment has remained in question. PURPOSE: We tested, in a prospective nonrandomized study, the hypothesis that neuroblast ploidy could be used as the sole guide for treatment selection in infants with unresectable or metastatic tumors and could differentiate between those who would respond to our previous standard regimen and those who would benefit from an immediate switch to another therapy. METHODS: One hundred seventy-seven infants were enrolled in this trial. Five of these infants were subsequently excluded (two ineligible, two lacking ploidy information, and one protocol violation); therefore, 172 patients were included in the study. One hundred thirty infants with hyperdiploid tumors (DNA index > 1.0; better prognosis in retrospective studies) were treated with a well-tolerated regimen of cyclophosphamide (150 mg/m2 per day orally or intravenously on days 1-7) and doxorubicin (35 mg/m2 intravenously on day 8). Forty-two infants with diploid tumors (DNA index = 1.0; worse prognosis in retrospective studies) received cisplatin (90 mg/m2 intravenously on day 1) and teniposide (100 mg/ m2 intravenously on day 3) after an initial course of cyclophosphamide plus doxorubicin. Statistical end points were response and long-term survival. In addition, we assessed within each ploidy group (i.e., patients with hyperdiploidtumors and those with diploid tumors) the prognostic significance of NMYC gene copy number, tumor stage, and other variables commonly measured in this disease.RESULTS: Of the 127 assessable infants with hyperdiploid tumors, 115 (91%) had complete responses--85 after receiving five courses of cyclophosphamide plus doxorubicin and 30 after receiving further therapy including cisplatin plus teniposide. The 3-year survival estimate for the entire hyperdiploid group was 94% (95% confidence interval [CI] = 89%-98%). Nineteen (46%) of 41 assessable infants with diploid tumors were complete responders. The overall 3-year survival estimate for this group was 55% (95% CI = 39%-70%). Prognostic factor analysis indicated that NMYC gene amplification and an elevated serum lactate dehydrogenase level were statistically significant markers of higher risk disease within the diploid group (two-sided P values of .005 and .003, respectively). Only NMYC was predictive in the hyperdiploid group (P = .003). CONCLUSION: Use of a prognostic staging system based on tumor cell ploidy, augmented with the NMYC gene copy number and serum level of lactate dehydrogenase, would very likely improve the treatment of infants with unresectable or metastatic neuroblastoma. Patients with diploid tumors characterized by an amplified NMYC locus represent a particularly unfavorable risk group that may benefit from innovative new therapies.

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.

BACKGROUND: In cancer treated with chemotherapy, multidrug resistance is characterized by increased genetic expression of P-glycoprotein (P-gp), which acts as an ATP-dependent drug-efflux pump. However, the clinical significance ofthe expression of the multidrug resistance gene (MDR1) product P-gp in neuroblastoma (NB) is still a matter of debate. In this study, the role of the expression of P-gp in NB was evaluated. METHODS: NB tumor imprints and NB positive bone marrow smears from 23 children before and after multidrug chemotherapy were examined for P-gp expression by antialkaline phosphatase immunocytochemical analysis. RESULTS: Before chemotherapy, only 10% of the NB samples showed positivity for P-gp. At diagnosis, no difference in P-gp expression was found between primary tumor cells and NB cells from metastases tobone marrow. P-gp positivity was only observed in patients with nonlocalized disease. P-gp positivity was never found in tumor cells that were histologicallywell differentiated. No clear correlation of P-gp positivity with poor prognostic parameters, such as chromosome 1p deletion or MYCN amplification, were found. Multidrug chemotherapy did not induce enhanced expression of P-gp in the neuroblasts. However, at clinical recurrence, P-gp expression was found in the metastatic NB cells of five of seven bone marrow samples examined. CONCLUSIONS: The prognostic relevance of P-gp expression in NB was not clear from the resultsof this study. To resolve the uncertainties, a standardization of the methodology and more prospective studies are needed to determine whether routine analysis ofP-gp is worth adding to the other prognostic parameters that are evaluated in NBpatients. The finding that metastatic cells are capable of expressing MDR1, in contrast to the NB cells of the primary tumor, would certainly be an interestingtopic for further study as work directed at understanding the progression to metastasis continues.

Amplification of the N-myc gene is a significant adverse prognostic factor in neuroblastoma, a common childhood tumor. In non-transformed cells, myc expression is controlled through an autoregulatory circuit, through which elevated Myc protein levels lead to down-regulation of myc transcription. The precise mechanism of myc gene autoregulation is unknown. Loss of c-myc autoregulation has been documented in transformed cells from a number of different lineages, but N-myc autoregulation has not yet been investigated. In neuroblastoma, the increased N-Myc protein produced by amplified tumors would be expected to silence N-myc transcription if the autoregulatory loop were intact. To determine whetherN-myc autoregulation is operative in human neuroblastoma, and to localize cis-acting elements which mediate N-myc autosuppression, we transfected a seriesof N-myc 5' promoter constructs into a panel of human neuroblastoma cell lines carrying one or multiple copies of N-myc. The transfected promoter was equally active in single-copy and amplified lines. Significant promoter activity in the presence of abundant Myc protein in amplified neuroblastoma lines indicates thatautoregulation is disabled in this subset of tumors. To investigate whether single-copy lines produce insufficient N-Myc protein to trigger autosuppression yet retain an intact autoregulatory circuit, we transfected neuroblastoma lines with 5' promoter constructs in the presence of a c- or N-myc expression vector. Overexpression of c- or N-Myc resulted in diminution of activity of both the transfected promoter and the endogenous N-myc gene in single-copy, but not amplified lines. Using a series of 5' promoter-deletion minigenes, we localized a cis-acting element required for autoregulation close to the transcription start sites. While the precise mechanism of autosuppression remains unknown, we demonstrated that Myc is incapable of silencing the adenovirus major late promoter (AdMLP) in neuroblastoma cells, indicating that Myc suppression of its own promoter and the AdMLP involve distinct components. These studies provide the first systematic investigation of autoregulation in neuroblastoma, and indicate that single-copy neuroblastoma lines produce insufficient N-Myc protein to activate downstream effector(s) of autosuppression; the autoregulatory circuit is otherwise intact. Amplified lines, in contrast, have lost autoregulation.

Amplification of the MYCN oncogene is a strong predictor of treatment failure and chemo-resistance in childhood neuroblastoma. Stable expression of two partial MYCN gene fragments in antisense orientation reduced Mycn protein expression in an MYCN-amplified neuroblastoma tumor cell line, however, antisense cells did not exhibit an increased in vitro sensitivity to cytotoxic or differentiating agents. In contrast, partial MYCN sense transfectants exhibited increased resistance to cytotoxic drugs. These data suggest that the chemo-resistance of MYCN-amplified neuroblastoma cells is complex, and may be due to factors additional to Mycn protein expression.

Disseminated neuroblastoma frequently show a very poor prognosis. N-myc gene amplification, 1p deletion and lack of CD44 gene expression, are ALL genetic factors associated with the disease's dissemination. Human neuroblastoma xenografts in nude mice has permitted to characterize, in disseminated neuroblasts, oncogenes overexpression, inactivation of tumor suppressor genes aswell as detoxifying genes activation which contributes to increase cellular resistance to chemotherapy. These genetic abnormalities permit to propose a nosology of this very aggressive pediatric solid tumor. Hopefully, this genetic classification could be of great value for new therapeutic approaches.

PURPOSE: To assess the significance of MYCN gene expression as a prognostic factor in patients with neuroblastoma of various ages, and to determine whether it can predict for outcome independently of MYCN gene amplification. PATIENTS AND METHODS: The level of MYCN gene expression in 60 specimens of primary untreated neuroblastoma was determined by reverse-transcriptase polymerase chain reaction (RT-PCR) analysis. RESULTS: High levels of MYCN gene expression were associated with advanced tumor stage (P=.0005), with the presence of MYCN gene amplification (P < .0001), but not with older age at diagnosis. Among patients who lacked MYCNgene amplification, the levels of MYCN gene expression were significantly greater in the tumors of infants compared with those of older children (P < .0005). HighMYCN expression was strongly associated with reduced survival and event-free survival in the overall study population (P < .005), and also in the subset of patients aged older than 1 year at diagnosis (P < .001). In contrast, MYCN expression did not appear to be predictive of outcome in infants. After adjustment for the effect of MYCN amplification, high levels of MYCN expression retained significant prognostic value for poor survival (relative hazards, 30.3;P=.003) in children aged older than 12 months at diagnosis. CONCLUSION: High MYCN gene expression is strongly predictive of poor outcome in older children with neuroblastoma, but not in infants. The findings help explain the controversy in the literature about the prognostic value of MYCN gene expression and highlight the different biology of neuroblastoma that presents in infants and older children.

We reported previously that the relative level of gene expression for sst2, a subtype of somatostatin receptors, was positively related to patient outcome in the childhood tumor neuroblastoma (NB). Because sst2 binds with high-affinity octreotide and its scintigraphic derivative, 111In-pentetreotide, we tested the hypothesis of whether NB tumor imaging with 111In-pentetreotide gives similar information to ex vivo measurement of sst2 expression. We, therefore, studied simultaneously nine NB tumors with 111In-pentetreotide single photon emission computed tomography and competitive reverse transcription-PCR for sst2, along with other prognostic markers. To quantitate the relative abundance of 111In-pentetreotide binding to NB tumors, we developed a simple semiquantitativemethod, based on the mathematical analysis of 111In-pentetreotide association tocancer cell receptors at different time points (4 and 24 h). We indeed found that the ratio between the activity in a manually extracted region of interest from pathological (ROIT) and background (ROINT) area was increasing between early andlate acquisition only in affected tissues. The rate of this pathological increase was quite different among patients and significantly (P < 0.01) related to the abundance of sst2 gene expression, as measured by competitive reverse transcription-PCR on ex vivo tumor samples. Because we demonstrated that in 26 NB patients the density of sst2 is strongly related to survival (P < 0.0005) and apparently independent from N-myc oncogene amplification (P < 0.05), we propose that NB tumor imaging with 111In-pentetreotide may have not only a diagnostic but also a prognostic value.