3481

IGF2

C11orf43|IGF-II|PP9974;insulin-like growth factor 2 (somatomedin A);IGF2;insulin-like growth factor 2 (somatomedin A)

insulin-like growth factor II|insulin-like growth factor type 2|somatomedin-A

11p15.5

protein-coding

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.

It has been previously shown that adrenocortical tumors (ACT) in adults exhibit structural abnormalities in tumor DNA in approximately 30% of cases. These abnormalities involve chromosome 11p15 and include loss of heterozygosity, paternal isodisomy, and overexpression of the gene for insulin-like growth factor II (IGF2), correlating with DNA demethylation at this locus. It has been hypothesized that these events occur late in the tumorigenic process in adults and seem to correlate with a worse prognosis. We present 4 pediatric cases of ACT diagnosed at 2.5 yr, 10 months, 12 yr, and 2.2 yr. ALL 4 patients presented withvirilization, and 1 patient also showed signs and symptoms of glucocorticoid excess. The youngest patient's maternal aunt had surgical excision of a more than 15-cm ACT 18 yr previously, but the aunt is doing well at age 23 yr. They ALL had surgical removal of their tumors. The 2.5-yr-old child also received chemotherapy and radiotherapy because of capsular rupture and, after 3 local recurrences, died 3.3 yr after initial presentation. We investigated ALL 4 tumors for chromosome 11 structural abnormalities (11p15.5 to 11q23), IGF2 and H19 expression by competitive RT-PCR analysis, and IGF2 methylation patterns by Southern analysis.All 4 tumors (100%) showed a combination of structural abnormalities at the 11p15 locus with mosaic loss of heterozygosity involving 11p. ALL tumors also had significantly increased IGF2 messenger ribonucleic acid levels relative to normal adrenal (up to 36-fold) and significant IGF2 demethylation (mean, 87%). H19 messenger ribonucleic acid levels were undetectable in 3 of 4 tumors, explained in part by mosaic loss of the actively expressed maternal allele for this imprinted gene. By immunohistochemistry we were able to confirm increased IGF-IIpeptide levels within the tumor tissue in 10 pediatric patients, including the 4patients described above. Concomitantly, we also observed nuclear accumulation of p53, suggesting somatic mutations. For the 10-month-old patient, sequencing revealed a p53 germline mutation. We therefore conclude that in pediatric ACT, structural abnormalities of tumor DNA and IGF2 overexpression as well as p53 mutations are very common and are therefore less useful for prognosis than in adults. Our findings support the theory that pediatric ACT, whose IGF2 expression and steroidogenesis evoke the phenotype of the fetal adrenal cortex, may arise because of defective apoptosis.

Hepatoblastomas (HBs), representing malignant liver tumors of childhood, show frequent loss of heterozygosity (LOH) in the chromosomal region 11p15.5. This loss is of maternal origin suggesting the presence of a monoallelically expressed tumor suppressor gene in this region. p57(KIP2) (KIP2) located at 11p15.5 is predominantly expressed from the maternal allele and encodes a cyclin-dependent kinase inhibitor. We screened a series of 56 HB tumors and five HB cell lines for allelic loss (LOH) of the KIP2 locus by microsatellite analysis and KIP2 coding sequence mutations by single-strand conformation polymorphism analysis. AlthoughLOH at the KIP2 locus occurred in 25% of the cases, no mutations were found. Analysis of KIP2 mRNA expression by competitive reverse transcriptase-polymerasechain reaction revealed up-regulation in nine of 12 HBs compared to matching liver samples. In contrast, mRNA levels of the putative suppressor gene H19 on 11p15.5 were decreased in 10 of 12 tumors, indicating that KIP2 and H19 are not co-regulated in HBs. IGF2 mRNA expression was increased in 11 of 12 HB samples. ALL HBs showed monoallelic KIP2 expression. However, the overexpression of KIP2 in HBs with maternal loss of 11p15.5 suggests a reactivation of the paternal allele in these cases. Overexpression of KIP2 in HBs argues against a role as a HB suppressor gene.

Recent findings have indicated that Insulin-like growth factors (IGF-I and IGF-II) may play a role in neoplasia. expression of their genes, which are highly complex structures, is tissue-specific and developmentally regulated. The purpose of the present study was to determine whether a relationship exists between tumorigenesis and the structure and expression of IGF genes. The structures of the IGF-I and IGF-II genes were investigated in 40 tumors by Southern blot analysis but no obvious re-arrangements (such as amplification or deletion) wereobserved in any of the tissues investigated. DNA methylation was also studied, using the enzyme Avall. The extent of DNA methylation of the IGF genes was highly variable in most of the tumors, as was the level of mRNA expression. A relationship could be detected between IGF over-expression and gene demethylation in tumors associated with hypoglycemia and in certain hepatocarcinomas. Loss of heterozygosity has been reported in the 11p15 region of some childhood tumors. The present findings provide further evidence of this loss of heterozygosity forthe IGF-II gene and show an imbalance in the leukocyte alleles in several childhood tumors. Likewise, an imbalance in the alleles was noted in several adult tumors, including hepatocarcinomas and breast cancers. This suggests that in certain adult tumors alterations of the IGF-II gene may be associated with tumorigenesis, but in other tumors another mechanism may be involved.

The most common known molecular defect in Wilms tumor (WT) of the kidney, the most frequent solid tumor of childhood, is loss of imprinting (LOI) of the insulin-like growth factor-II gene (IGF2), which involves activation of the normally silent maternal allele of the gene and hypermethylation of a differentially methylated region upstream of the H19 gene. Hypermethylation impairs binding of the insulator protein CTCF, allowing activation of IGF2 by anenhancer shared between IGF2 and H19. Loss of heterozygosity (LOH) of 16q22.1 isfound in 15% of WTs, and 16q22.1 harbors CTCF, raising the possibility that reduced CTCF could lead to LOI of IGF2 in some cases. We hypothesized that thereis an association between LOH of 16q and LOI of IGF2 in WT. In 40 WTs examined, LOH of 16q was found in five, one of which also showed LOH of 11p15. ALL of the remaining four tumors showed LOI of IGF2, compared to 13 of 32 WTs without LOH of 16q or 11p (P = 0.040). When published data not previously analyzed in this manner were included, 6 of 6 tumors with 16q LOH (and without LOH of 11p) showedLOI of IGF2, compared to 24 of 52 without LOH (P = 0.015). Thus, a genetic (16q LOH) and an epigenetic (LOI of IGF2) alteration in WT are linked, the first suchassociation described. Finally, haploinsufficiency of CTCF may be the basis of this association, given that CTCF expression in tumors with 16q LOH was 48% thatof tumors without LOH.#CI- Copyright 2005 Wiley-Liss, Inc.

BACKGROUND: Adrenocortical tumors are heterogeneous neoplasms with incompletely understood pathogenesis. IGF-II overexpression has been consistently demonstrated in adult adrenocortical carcinomas. OBJECTIVES: The objective of the study was to analyze expression of IGF-II and its receptor (IGF-IR) in pediatric and adult adrenocortical tumors and the effects of a selective IGF-IR kinase inhibitor (NVP-AEW541) on adrenocortical tumor cells. PATIENTS: Fifty-seven adrenocorticaltumors (37 adenomas and 20 carcinomas) from 23 children and 34 adults were studied. METHODS: Gene expression was determined by quantitative real-time PCR. Cell proliferation and apoptosis were analyzed in NCI H295 cells and a new cell line established from a pediatric adrenocortical adenoma. RESULTS: IGF-II transcripts were overexpressed in both pediatric adrenocortical carcinomas and adenomas. Otherwise, IGF-II was mainly overexpressed in adult adrenocortical carcinomas (270.5 +/- 130.2 vs. 16.1 +/- 13.3; P = 0.0001). IGF-IR expression was significantly higher in pediatric adrenocortical carcinomas than adenomas (9.1 +/- 3.1 vs. 2.6 +/- 0.3; P = 0.0001), whereas its expression was similar in adult adrenocortical carcinomas and adenomas. IGF-IR expression was a predictor of metastases in pediatric adrenocortical tumors in univariate analysis (hazard ratio 1.84; 95% confidence interval 1.28-2.66; P = 0.01). Furthermore, NVP-AEW541 blocked cell proliferation in a dose- and time-dependent manner in both cell lines through a significant increase of apoptosis. CONCLUSION: IGF-IR overexpression was a biomarker of pediatric adrenocortical carcinomas. Additionally, a selective IGF-IR kinase inhibitor had antitumor effects in adultand pediatric adrenocortical tumor cell lines, suggesting that IGF-IR inhibitorsrepresent a promising therapy for human adrenocortical carcinoma.

pediatric undifferentiated soft tissue sarcomas (USTSs) are tumors composed of primitive mesenchymal cells. As such, they form an attractive model for studyingthe early events in sarcoma development. In an effort to better understand the critical molecular aberrations leading to sarcoma development, gene expression array analysis and post-array validation techniques were applied to several USTSs; the results were consistent with upregulation of the excitatory components of the insulin-like growth factor (IGF) pathway. Particularly high expression ofthe insulin-like growth factor 2 (IGF2) ligand was seen and confirmed by real-time reverse transcriptase-polymerase chain reaction. Immunohistochemistry performed using antibodies against IGF2 revealed overexpression of the IGF2 protein in 19 of 21 (90%) USTSs and revealed 2 distinct staining patterns, 1 in which there was diffuse cytoplasmic staining (16/19) and 1 in which there was punctate perinuclear positivity (3/19). Using ultrastructural immunogold localization of IGF2, it was determined that IGF2 was primarily localized to Golgi-derived vesicles and multivesicular bodies in tumor cells showing the punctate pattern, and to both the cytoplasm and plasma membrane of tumor cells showing the diffuse pattern. The results suggest that upregulation of the IGF pathway in pediatric USTSs is a critical early event in the development of sarcomas. Furthermore, findings from the immunocytochemical and immunogold analyses confirm the presence of 2 different cytoplasmic trafficking patterns and storage motifs of IGF2 within this type of tumor. Given that in one subcellular pattern the IGF2 protein does not appear to reach the membrane, these findings may have functional significance.

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

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.

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

During normal sympathetic nervous system (SNS) development, cells of the ganglionic lineage can malignantly transform and develop into the childhood tumor neuroblastoma. Hypoxia-inducible transcription factors (HIFs) mediate cellular responses during normal development and are central in the adaptation to oxygen shortage. HIFs are also implicated in the progression of several cancer forms, and high HIF-2alpha expression correlates with disseminated disease and poor outcome in neuroblastoma. During normal SNS development, HIF2A is transiently expressed in neuroblasts and chromaffin cells. SNS cells can, during development, be distinguished by distinct gene expression patterns, and insulin-like growth factor 2 (IGF2) is a marker of sympathetic chromaffin cells, whereas sympatheticneuroblasts lack IGF2 expression. Despite the neuronal derivation of neuroblastomas, we show that neuroblastoma cell lines and specimens express IGF2and that expression of HIF2A and IGF2 correlates, with the strongest correlationin high-stage tumors. In neuroblastoma, both IGF2 and HIF2A are hypoxia-driven and knocking down IGF2 at hypoxia resulted in downregulated HIF2A levels. HIF-2alpha and IGF2 were strongly expressed in subsets of immature neuroblastomacells, suggesting that these two genes could be co-expressed also at early stages of SNS development. We show that IGF2 is indeed expressed in sympathetic chain ganglia at embryonic week 6.5, a developmental stage when HIF-2alpha is present.These findings provide a rationale for the unexpected IGF2 expression in neuroblastomas and might suggest that IGF2 and HIF2A positive neuroblastoma cells are arrested at an embryonic differentiation stage corresponding to the stage when sympathetic chain ganglia begins to coalesce.

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.

H19 and insulin-like growth factor II (IGF2) are among a few genes which have been confirmed to be imprinted in normal human embryonal tissues. This results in monoallelic expression of maternal H19 and paternal IGF2. Loss of imprinting of these genes producing biallelic expression has been observed in Wilm's tumor andembryonal rhabdomyosarcoma, suggesting that an epigenetic change of DNA, in addition to a genetic change in oncogene(s) and/or tumor suppressor gene(s), maybe involved in the development of these childhood cancers. Neuroblastoma, which is an embryonal tumor originating from neural crest-derived cells, occasionally occurs in individuals with the Beckwith-Wiedemann syndrome; Wilm's tumor and embryonal rhabdomyosarcoma occur even more frequently in the Beckwith-Wiedemann syndrome; and paternal uniparental disomy of H19 and IGF2 loci (chromosome 11p15) is present in the Beckwith-Wiedemann syndrome. Furthermore, neuroblastoma cell lines express IGF2, and autocrine/paracrine effects of IGF2 have been demonstrated in these cells. Thus, we examined for imprinting of both H19 and IGF2 in primary untreated neuroblastomas using the RsaI and ApaI polymorphisms within these genes, respectively. Seven of 15 tumors were informative for H19 and for IGF2, and ALL of these cases showed monoallelic expression of both of these genes. These results indicate that loss of imprinting of H19 and IGF2 does not occur in neuroblastomas.

Neuroblastoma is a childhood tumor of the sympathetic nervous system. Observations in the Beckwith-Wiedemann syndrome suggest that sympathetic embryonal cells with an abundant expression of the insulin-like growth factor 2 gene (IGF2) may be involved in the genesis of low-malignant infant neuroblastomas. We have therefore compared the cell type-specific IGF2 expression of the human sympathetic nervous system during early development with that of neuroblastoma. An abundant expression in normal sympathetic tissue was specific to extra-adrenal chromaffin cells, ie, paraganglia and small intensely fluorescent (SIF) cells, whereas sympathetic neuronal cells were IGF2-negative. A subpopulation of neuroblastomas expressed IGF2, which correlated with an early age at diagnosis, an extra-adrenal tumor origin, and severe hemodynamic signs ofcatecholamine secretion. Histologically IGF2-expressing tumors displayed a lobular growth pattern, and expression was restricted to the most mature and least proliferative cells. Typically, these cells were morphologically and histochemically similar to paraganglia/SIF cells and formed distinct ring-like zones in the center of the lobules around a core of apoptosis-like tumor cells. The similarities found between IGF2-expressing neuroblastoma cells and paraganglia/SIF cells in terms of histological features, anatomical origin, and age-dependent growth suggest a paraganglionic/SIF cell lineage of most infant tumors and also of extra-adrenal tumors diagnosed after infancy. Furthermore, since paraganglia/SIF cells undergo postnatal involution, the same cellular mechanism may be responsible for spontaneous regression in infant neuroblastoma.

Uterine leiomyosarcomata, malignant smooth-muscle tumors that may arise from existing leiomyomata or directly from the myometrium, have been shown to oversecrete insulin-like growth factor II (IGF-II). It has been shown recently that the IGF-II gene (IGF2) is maternally imprinted in both mice and humans. Only the paternal allele of IGF2 is usually expressed, except in adult liver and in the central nervous system in which biallelic expression is seen. Recently, lossof IGF2 imprinting has been reported in Wilms' tumor and in several other malignancies, and it has been suggested that biallelic expression of the gene leads to overexpression of IGF-II peptide and increased mitogenic activity. Using the ApaI restriction enzyme polymorphism in exon 9 of IGF2, we examined the expression of IGF2 in five informative uterine leiomyosarcomata and found that IGF2 was expressed biallelically in two tumors. In contrast, five samples of normal myometrium and six informative benign uterine leiomyomata showed monoallelic expression of IGF2. The incidence of heterozygosity at this locus was markedly lower in patients with leiomyosarcoma (6%) than in the healthy population (42% heterozygous; P < 0.01). H19, a gene that is imprinted in normaltissues, was expressed monoallelically in ALL informative normal and neoplastic uterine tumors. In contrast, the IGF-II receptor gene was expressed from both alleles in ALL tissues examined, confirming the finding that the human IGF-II receptor gene is not imprinted in humans. This study provides further evidence that relaxation of IGF2 genomic imprinting occurs not only in childhood tumors but also in adult-onset tumors, and it suggests a novel epigenetic mechanism foroncogenesis throughout life.

Little is known about the pathophysiology of sporadic adrenocortical tumors in adults. Because loss of heterozygosity at the 11p15 locus has been described in childhood tumors, particularly, in adrenocortical tumors, associated with the Beckwith-Wiedemann syndrome and because insulin-like growth factor-II (IGF-II) is a crucial regulator of fetal adrenal growth, we looked for structural analysis at the 11p15 locus and IGF-II gene expression in 23 sporadic adrenocortical adult tumors: 6 carcinomas (5 with Cushing's syndrome and 1 nonsecreting) and 17 benign adenomas (13 with Cushing's syndrome, 1 pure androgen secreting, and 3 nonsecreting). Twenty-one patients were informative at the 11p15 locus, and six (four carcinomas and two adenomas) of them (28.5%) exhibited 11p15 structural abnormalities in tumor DNA (five, an uniparental disomy and one, a mosaicism). In a single case that could be further studied, a paternal isodisomy was observed. Very high IGF-II mRNA contents were detected in seven tumors (30%; 5 of the 6 carcinomas and 2 of the 17 adenomas). They were particularly found in tumors with uniparental disomy at the 11p15 locus. Overall, a strong correlation existed between IGF-II mRNA contents and DNA demethylation at the IGF-II locus. These data show that genetic alterations involving the 11p15 locus were highly frequent in malignant tumors, but found only in rare adenomas. These results in combination with evidence for overexpression of IGF-II from the 11p15.5 locus suggest that abnormalities in structure and/or expression of the IGF-II gene play a role as a late event of a multistep process of tumorigenesis.

Embryonal kidney cell tumors develop in rats given the alkylating agent N-nitroso-N'-methylurea as neonates. These tumors resemble the childhood Wilms tumors in their histopathology. Deletions and mutations in the Wilms tumor suppressor gene, WT1, are present in up to 6% of childhood nephroblastomas. To investigate the role of WT1 in rat kidney tumorigenesis, we studied the genetic alterations in WT1 and its target genes. Point mutations were found in WT1 cDNA in 7 of 18 kidney tumors. Mesenchymal tumors contained G-->A transition mutations in codons 128, 364, and 372, typical of the methylating action of N-nitroso-N'-methylurea on DNA. Each of the four nephroblastomas contained the same T-->A mutation at codon 111 of WT1, reflective of transversion mutagenesis by N-nitroso-N'-methylurea in vivo. Like Wilms tumors, mRNA levels of WT1, IGF2,Pax-2, and MK genes were higher than newborn kidney in the majority of the tumors. The histopathology of the rat kidney tumors and the genetic alterations are reminiscent of those observed in Wilms tumors, establishing this as a relevant model system for the human disease.

Overstimulation by insulin-like growth factor II is implied in several overgrowth conditions and childhood cancers. We have therefore studied spatial and temporalexpression patterns of the insulin-like growth factor II gene (IGF2) and the insulin-like growth factor type 1 receptor gene during normal human development (5.5 to 23.0 weeks postfertilization). The set of cell types with the most abundant IGF2 expression correlated strikingly to the organomegaly and tumor predisposition of the Beckwith-Wiedemann syndrome. Intrauterine growth and postnatal organ weights of a prematurely born child with a full-blown syndrome are presented. The cell type-specific IGF2 expression of these organs and of multifocal Wilms' tumors from two other children affected by the Beckwith-Wiedemann syndrome were also studied. The results clarify and extend previous findings concerning human prenatal IGF2 expression and are consistent with a short range overstimulatory role of locally produced IGF II ensuing afterthe first trimester in the Beckwith-Wiedemann syndrome.

PURPOSE: Developmentally imprinted genes, such as H19 and insulin-like growth factor-II (IGF-II), play an important role during human embryogenesis and also have been implicated in the pathogenesis of embryonal tumors of childhood. SinceH19 is expressed in human fetal bladder, we evaluated 35 bladder carcinomas for H19 expression by in situ hybridization analysis and correlated expression with tumor grade. As a prelude to gene transfer studies to determine if H19 is a bladder tumor oncogene, we also evaluated bladder cell lines for expression of H19, IGF-II, IGF-I and the type I IGF receptor. MATERIALS AND METHODS: H19 expression was evaluated by in situ hybridization analysis in bladder tumor specimens. Northern analysis was used to evaluate the expression of H19, IGF-II,IGF-I and the type I IGF receptor in bladder cell lines. RESULTS: H19 was expressed preferentially in advanced stage tumors: 2 of 12 grade I tumors were H19 positive, whereas 9 of 11 grade II and 7 of 10 grade III tumors expressed H19 (p = 0.004). Additionally, 6 of 6 carcinoma in situ tumors were H19 positive, whereas normal bladder mucosa cells were H19 negative. We found that 3 of 11 cell lines (HT-1376, HT-1197 and 5637) express high levels of H19 mRNA, and each of these cell lines and J82 also express IGF-II. ALL cell lines examined expressed the type I IGF receptor, whereas there was no detectable IGF-I mRNA. CONCLUSIONS: These data demonstrate that H19 is an oncodevelopmental marker of bladder tumor progression and raise the possibility that H19 may have oncogenic properties in bladder cancer.

Beckwith-Wiedemann syndrome (BWS) involves fetal overgrowth and predisposition to a wide variety of embryonal tumors of childhood. We have previously found that BWS is genetically linked to 11p15 and that this same band shows loss of heterozygosity in the types of tumors to which children with BWS are susceptible. However, 11p15 contains > 20 megabases, and therefore, the BWS and tumor suppressor genes could be distinct. To determine the precise physical relationship between these loci, we isolated yeast artificial chromosomes, and cosmid libraries from them, within the region of loss of heterozygosity in embryonal tumors. Five germ-line balanced chromosomal rearrangement breakpoint sites from BWS patients, as well as a balanced chromosomal translocation breakpoint from a rhabdoid tumor, were isolated within a 295- to 320-kb cluster defined by a complete cosmid contig crossing these breakpoints. This breakpoint cluster terminated approximately 100 kb centromeric to the imprinted gene IGF2 and 100 kb telomeric to p57KIP2, an inhibitor of cyclin-dependent kinases, and was located within subchromosomal transferable fragments that suppressed the growth of embryonal tumor cells in genetic complementation experiments. We have identified 11 transcribed sequences in this BWS/tumor suppressor coincident region, one of which corresponded to p57KIP2. However, three additional BWS breakpoints were > 4 megabases centromeric to the other five breakpoints and were excluded from the tumor suppressor region defined by subchromosomal transferablefragments. Thus, multiple genetic loci define BWS and tumor suppression on 11p15.

We studied the expression of insulin-like growth factor II (IGF2) and Wilms' tumor gene (WT1) in nine cases of congenital mesoblastic nephroma (CMN) and fivecases of first trimester fetal kidneys by in situ hybridization. Our aim was to determine their site of expression and to correlate their histogenetic relationship to those of other childhood renal tumors. Our results showed that ALL nine cases of CMN (classic, mixed, and cellular) contained abundant IGF2 butnot WT1 transcripts. The IGF2 transcripts were diffusely distributed over the tumor cells. These findings suggest that CMN is derived from primitive mesenchymal nephrogenic cells and have a potential to differentiate into a stromal cell lineage.

The insulin-like growth factor II gene (IGF2) is imprinted in normal human tissues, and relaxation of imprinting (ROI) of IGF2 is thought to play an important role in human childhood tumors. Taking advantage of an Apa I polymorphism in this gene, allelic expression of IGF2 has now been examined in colorectal cancer. Thirteen of 33 patients studied were informative. Colorectal cancer tissue from 5 of the 13 informative patients exhibited ROI of IGF2; furthermore, normal mucosa from 3 of these 5 patients also showed weak biallelicexpression of IGF2. ROI of IGF2 may thus also play a role in colorectal cancer.

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.

The expression of Insulin-like Growth Factor 2 (IGF-2) and H19, two genes located on human chromosome 11p15 and provided with cell growth modulating activity, is regulated by parental imprinting, in that the activity of their alleles is dependent on the parental origin. Parental bias in the genetic alterations of chromosome 11p15 observed in several pediatric cancers suggests the involvement of imprinted genes in tumor development. We have previously reported that the number of functional IGF-2 alleles is frequently increased in rhabdomyosarcoma (RMS), as a consequence of either relaxation of imprinting (LOI) or gene duplication. Here we show that the expression of the H19 gene is significantly suppressed with respect to normal muscle tissue in 13 out of 15 rhabdomyosarcomas with embryonal histology (ERMS) and in three out of 11 rhabdomyosarcomas classified as alveolar subtype (ARMS). Since a growth-inhibitory activity has been found associated with the H19 gene, the extinction of its expression can contribute to RMS development. Parental imprinting of the H19 gene was found conserved in ALL informative RMSs, including those whose ICF-2 imprinting was relaxed, indicating that LOI is a gene-specific event. Seven ERMSs and one ARMS displaying low H19 RNA levels showed an underrepresentation of the expressed allele in their genotype. This result is consistent with the paternal imprintingof the H19 gene and with the preferential loss of the maternal 11p15 alleles in these neoplasms. Low H19 expression was also found in four out of eight RMSs retaining the heterozygosity at 11p15, but showing IGF-2 LOI. These findings suggest that the genetic and epigenetic alterations affecting chromosome 11p15 in a high number of RMSs cause deregulation of more than one imprinted gene, possibly affecting tumor growth, including the extinction of H19 expression and an increase in the number of active IGF-2 alleles.

Comparisons of the developing human sympathetic nervous system (SNS) to tumors presumed to derive from these cells may suggest tumor progenitors and predict tumor biologic behavior. Classic neuroblastoma (NB) and its more highly differentiated stroma-rich subtypes, extra-adrenal sympathetic paraganglioma, and pheochromocytoma were examined for the presence of the developmentally characterized gene products NSE, S-100, CD44, Bcl-2, HNK-1, PNMT, TrkA, IGF2, and tyrosine hydroxylase. The marker gene expression profiles of these tumors were compared with those similarly determined for a number of normal prenatal and postnatal human SNS cell types. Sympathetic paraganglioma, pheochromocytoma, andstroma-rich NB display marker expression profiles mimicking those of childhood sympathetic paraganglia, adrenal chromaffin cells, and sympathetic neurons, respectively. A selection of differentiating, extra-adrenal NB tumors with prognostically favorable features possess marker gene expression profiles paralleling that observed for fetal extra-adrenal sympathetic paraganglia/small intensely fluorescent cells. In contrast, undifferentiated, clinically aggressive NB tumors manifest characteristics mirroring that of embryonic/early fetal sympathetic neuroblasts of sympathetic ganglia and of the adrenal gland. These findings suggest that clinical features, such as primary tumor location and age at diagnosis, provide prognostic information for NB patients by virtue of the existence and biology of the presumed tumor progenitor cell type.

The insulin-like growth factor II is mitogenic for a number of cell types and can inhibit apoptosis. The frequent expression of this gene in human and experimental animal tumors indicates that insulin-like growth factor-2 may play an important role in tumor development. It has also been hypothesized that overexpression of this growth factor may be responsible for the increased incidence of childhood tumors in patients with Beckwith-Wiedemann syndrome. To assess the effects of Igf2 on tumor development we produced six transgenic mouse lines that express the gene under the control of the H19 enhancers. Transgenic expression was initiatedin the embryonic period but remained high in several adult tissues, including the mammary gland, lung, and liver. Adult transgenic females from five of the transgenic lines developed often multiple mammary tumors that had the ability tometastasize. Increased incidence of other solid tumors was also noted in older mice. These findings indicate that Igf2 expression increases the probability of malignant transformation and that the mammary gland is at a particularly high risk of tumor development in response to chronic increase in Igf2 gene dosage.

BACKGROUND: Loss of imprinting (LOI) of insulin-like growth factor-2 (IGF-2) hasbeen implicated in the pathogenesis of certain human cancers and tumor-predisposing overgrowth disorders, such as Beckwith-Wiedemann syndrome. Ina previous study, the authors revealed that certain patients with childhood acute leukemia and neuroblastoma had had rapid somatic growth after birth, suggesting the involvement of growth factor(s) in tumorigenesis. In the current study, the authors examined whether relaxation of IGF-2 imprinting occurred in infant leukemia and childhood neuroblastoma. METHODS: The genomic DNA of infant leukemia, childhood neuroblastoma, and control individuals was amplified by polymerase chain reaction (PCR). Patients who had heterozygous genotype were selected as informative cases using Apa I polymorphism in exon 9 of the IGF-2 gene. Total RNA was isolated from informative cases, followed by cDNA synthesis.cDNA was amplified by PCR, and direct sequence was performed for determining allele specific transcription. RESULTS: Twenty of 22 infant leukemia blasts and ALL of 16 neuroblastoma cells showed normal monoallelic expression of IGF-2 as well as 23 controls. The height and weight of two acute lymphoblastic leukemia patients with LOI were within normal ranges for Japanese children. CONCLUSIONS: The current study revealed that the imprinting status of IGF-2 was generally maintained in infant leukemia and confirmed that it was maintained in childhood neuroblastoma. The results suggest that LOI of IGF-2 does not play a major role in the carcinogenesis of these diseases or in rapid physical growth of the patients.

BACKGROUND: Loss of imprinting (LOI) of insulin-like growth factor-2 (IGF-2) hasbeen implicated in the pathogenesis of certain human cancers and tumor-predisposing overgrowth disorders, such as Beckwith-Wiedemann syndrome. Ina previous study, the authors revealed that certain patients with childhood acute leukemia and neuroblastoma had had rapid somatic growth after birth, suggesting the involvement of growth factor(s) in tumorigenesis. In the current study, the authors examined whether relaxation of IGF-2 imprinting occurred in infant leukemia and childhood neuroblastoma. METHODS: The genomic DNA of infant leukemia, childhood neuroblastoma, and control individuals was amplified by polymerase chain reaction (PCR). Patients who had heterozygous genotype were selected as informative cases using Apa I polymorphism in exon 9 of the IGF-2 gene. Total RNA was isolated from informative cases, followed by cDNA synthesis.cDNA was amplified by PCR, and direct sequence was performed for determining allele specific transcription. RESULTS: Twenty of 22 infant leukemia blasts and ALL of 16 neuroblastoma cells showed normal monoallelic expression of IGF-2 as well as 23 controls. The height and weight of two acute lymphoblastic leukemia patients with LOI were within normal ranges for Japanese children. CONCLUSIONS: The current study revealed that the imprinting status of IGF-2 was generally maintained in infant leukemia and confirmed that it was maintained in childhood neuroblastoma. The results suggest that LOI of IGF-2 does not play a major role in the carcinogenesis of these diseases or in rapid physical growth of the patients.