cytidylyl-3--5--guanosine and Kidney-Neoplasms

XIAP-associated factor 1 (XAF1) is a new candidate tumor suppressor, which has been known to exert proapoptotic effects by interfering with the caspase-inhibiting activity of XIAP. To explore the XAF1's candidacy for a suppressor in urogenital tumorigenesis, we investigated the XAF1 status in a series of cancer cell lines and primary tumors derived from the bladder, kidney and prostate. Expression of XAF1 transcript was undetectable or extremely low in 60% (3/5) of bladder, 66% (10/15) of kidney, and 100% (3/3) prostate cancer cell lines. Abnormal reduction of XAF1 was also found in 33% (18/55) of primary bladder and 40% (8/20) of primary kidney tumors, and showed a correlation with advanced stage and high grade of bladder tumor. Hypermethylation at 14 CpG sites in the 5' proximal region of the XAF1 promoter was highly prevalent in cancers versus adjacent normal or benign tissues and tightly associated with reduced gene expression. XAF1 expression enhanced the apoptotic response of tumor cells to chemotherapeutic agents, such as etoposide or 5-FU. While XAF1 expression did not influence the subcellular distribution or expression of XIAP, it elevated the protein stability of p53 and its target gene expression. Moreover, the apoptosis-sensitizing and growth suppression function of XAF1 was markedly impeded by blockade of p53 function. Collectively, our study demonstrates that epigenetic alteration of XAF1 is frequent in human urogenital cancers and may contribute to the malignant progression of tumors by rendering tumor cells a survival advantage partially through the attenuated p53 response to apoptotic stresses.

Topics: Adaptor Proteins, Signal Transducing; Apoptosis Regulatory Proteins; Dinucleoside Phosphates; DNA Methylation; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Intracellular Signaling Peptides and Proteins; Kidney Neoplasms; Male; Neoplasm Proteins; Promoter Regions, Genetic; Prostatic Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; Tumor Suppressor Protein p53; Urinary Bladder Neoplasms; Urogenital Neoplasms

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

Mutational inactivation and allelic loss of the von Hippel-Lindau (VHL) gene appear to be causal events for the majority of spontaneous clear-cell renal carcinomas. We now show that hypermethylation of a normally unmethylated CpG island in the 5' region provides another potentially important mechanism for inactivation of the VHL gene in a significant portion of these cancers. This hypermethylation was found in 5 of 26 (19%) tumors examined. Four of these had lost one copy of VHL while one retained two heavily methylated alleles. Four of the tumors with VHL hypermethylation had no detectable mutations, whereas one had a missense mutation in addition to hypermethylation of the single retained allele. As would be predicted for the consequence of methylation in this 5' CpG island, none of the 5 tumors expressed the VHL gene. In contrast, normal kidney and all tumors examined with inactivating VHL gene mutations but no CpG island methylation had expression. In a renal cell culture line, treatment with 5-aza-2'-deoxycytidine resulted in reexpression of the VHL gene. These findings suggest that aberrant methylation of CpG islands may participate in the tumor-suppressor gene inactivations which initiate or cause progression of common human cancers.

Topics: Adenocarcinoma, Clear Cell; Base Sequence; Carcinoma, Renal Cell; Chromosome Aberrations; Dinucleoside Phosphates; DNA Primers; DNA, Neoplasm; Exons; Genes, Tumor Suppressor; Humans; Kidney Neoplasms; Methylation; Molecular Sequence Data; Mutation; Polymerase Chain Reaction; Restriction Mapping

Von Hippel-Lindau disease is a heritable tumour syndrome caused by the loss of the function of a tumour suppressor gene on the short arm of human chromosome 3. The interval RAF1-D3S18 (3p25-3p26) has been identified by genetic linkage studies to harbour the von Hippel-Lindau gene. We have constructed a long range restriction map of this region and have succeeded in demonstrating the physical linkage of loci D3S726 (DNA probe LIB31-38), D3S18 (c-LIB-1, L162E5), D3S601 (LIB19-63) and D3S587 (LIB12-48). Since multipoint analysis has located D3S601 proximal to D3S726, the physical map should be oriented with D3S726 towards the telomere. The order and distances of probes within the von Hippel-Lindau gene region is as follows: telomere--LIB31-38--(< 280 kb)--c-LIB-1--(overlapping)--L162E5--(900-1600 kb)--(LIB19-63, LIB12-48)--centromere. In tissues that included blood, semen and Epstein-Barr-virus-transformed lymphocytes, we detected a putative CpG island flanking D3S18.

Topics: Carcinoma, Renal Cell; Centromere; Chromosomes, Human, Pair 3; Dinucleoside Phosphates; Electrophoresis, Gel, Pulsed-Field; Gene Expression Regulation, Neoplastic; Genes, Tumor Suppressor; Genetic Linkage; Humans; Kidney Neoplasms; Restriction Mapping; Telomere; Tumor Cells, Cultured; von Hippel-Lindau Disease

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