cytidylyl-3--5--guanosine and Wilms-Tumor

The Beckwith-Wiedemann syndrome (BWS) is marked by fetal organ overgrowth and conveys a predisposition to certain childhood tumors, including Wilms tumor (WT). The genetics of BWS have implicated a gene that maps to chromosome 11p15 and is paternally imprinted, and the gene encoding the cyclin-cdk inhibitor p57KIP2 has been a strong candidate. By complete sequencing of the coding exons and intron/exon junctions, we found a maternally transmitted coding mutation in the cdk-inhibitor domain of the KIP2 gene in one of five cases of BWS. The BWS mutation was an in-frame three-amino-acid deletion that significantly reduced but did not fully abrogate growth-suppressive activity in a transfection assay. In contrast, no somatic coding mutations in KIP2 were found in a set of 12 primary WTs enriched for cases that expressed KIP2 mRNA, including cases with and without 11p15.5 loss of heterozygosity. Two other 11p15.5 loci, the linked and oppositely imprinted H19 and IGF2 genes, have been previously implicated in WT pathogenesis, and several of the tumors with persistent KIP2 mRNA expression and absence of KIP2 coding mutations showed full inactivation of H19. These data suggest that KIP2 is a BWS gene but that it is not uniquely equivalent to the 11p15.5 "WT2" tumor-suppressor locus.

Topics: Beckwith-Wiedemann Syndrome; Cells, Cultured; Child, Preschool; Chromosomes, Human, Pair 11; Cyclin-Dependent Kinase Inhibitor p57; Cyclin-Dependent Kinases; Dinucleoside Phosphates; DNA Methylation; DNA Mutational Analysis; Enzyme Inhibitors; Female; Genes, Wilms Tumor; Genetic Predisposition to Disease; Genomic Imprinting; Germ-Line Mutation; Humans; Infant; Kidney Neoplasms; Male; Muscle Proteins; Nuclear Proteins; Polymorphism, Single-Stranded Conformational; RNA, Long Noncoding; RNA, Untranslated; Sequence Deletion; Wilms Tumor

Genomic imprinting and monoallelic gene expression appear to play a role in human genetic disease and tumorigenesis. The human H19 gene, at chromosome 11p15, has previously been shown to be monoallelically expressed. Since CpG methylation has been implicated in imprinting, we analyzed methylation of H19 DNA. In fetal and adult organs the transcriptionally silent H19 allele was extensively hypermethylated through the entire gene and its promoter, and, consistent with a functional role for DNA methylation, expression of an H19 promoter-reporter construct was inhibited by in vitro methylation. Gynogenetic ovarian teratomas were found to contain only hypomethylated H19 DNA, suggesting that the expressed H19 allele might be maternal. This was confirmed by analysis of 11p15 polymorphisms in a patient with Wilms tumor. The tumor had lost the maternal 11p15, and H19 expression in the normal kidney was exclusively from this allele. Imprinting of human H19 appears to be susceptible to tissue-specific modulation in somatic development; in one individual, cerebellar cells were found to express only the otherwise silent allele. Implications of these findings for the role of DNA methylation in imprinting and for H19 as a candidate imprinted tumor-suppressor gene are discussed.

Topics: Adult; Alleles; Base Sequence; Chromosomes, Human, Pair 11; Dinucleoside Phosphates; DNA, Neoplasm; Female; Fetus; Humans; Methylation; Molecular Sequence Data; Ovarian Neoplasms; Promoter Regions, Genetic; Teratoma; Wilms Tumor

Wilms tumor is an embryonal kidney tumor involving complex pathology and genetics. The Wilms tumor locus on chromosome 11p13 is defined by the region of overlap of constitutional and tumor-associated deletions. Chromosome walking and yeast artificial chromosome (YAC) cloning were used to clone and map 850 kilobases of DNA. Nine CpG islands, constituting a "CpG island archipelago," were identified, including three islands that were not apparent by conventional pulsed-field mapping, and thus were at least partially methylated. Three distinct transcriptional units were found closely associated with a CpG island within the boundaries of a homozygous DNA deletion in a Wilms tumor.

Topics: Chromosome Mapping; Chromosome Walking; Chromosomes, Human, Pair 11; Dinucleoside Phosphates; DNA Probes; Genes, Wilms Tumor; Humans; Transcription, Genetic; Wilms Tumor

We have isolated a DNA segment absent from all the constitutionally deleted chromosomes 11 of our patients with Wilms tumor. This marker separates two balanced translocations that break in band 11p13: the distal one associated with aniridia (AN2), and the proximal one with genitourinary dysplasia (GUD). The GUD breakpoint maps within the smallest region of overlap (SRO) for the Wilms tumor (WT) gene locus, thus strengthening the previous suggestion of an association between Wilms tumor and other abnormalities of the genitourinary system. The 11p13 translocation breakpoint associated with T-cell acute lymphatic leukemia (T-ALL) is centromeric to the SRO and separated from the WT locus by at least one known gene. This region of the human genome (11p13) is rich in CpG islands that potentially identify genes, some of which may be involved in the various phenotypes associated with the WAGR syndrome. This is consistent with the proposition that the majority of human genes are in G-negative bands.

Topics: Animals; Aniridia; Blotting, Southern; Chromosome Mapping; Chromosomes, Human, Pair 11; Dinucleoside Phosphates; DNA; Genes; Humans; Hybrid Cells; Kidney Neoplasms; Mice; Restriction Mapping; Syndrome; Translocation, Genetic; Urogenital Abnormalities; Wilms Tumor