cytidylyl-3--5--guanosine and Carcinoma--Renal-Cell

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