CLONING TUMOR SUPPRESSOR GENES (TSG) FROM HUMAN CHROMOSOME 3P

我们今年的主要成就有：(1)VHL基因测序

Our major accomplishments this year are: (1) sequencing the VHL gene including promoter, exons, introns, and flanks altogether comprising 16kb; (2) identification of pVHL target genes by using differential display technology; to date 120 primer pairs were tested and so far two down regulated genes identified, namely, HL31 a ribosomal protein gene overexpressed in colon cancer and FAP, and an intracellular receptor for PKC (a homolog of the beta subunit of G proteins). (3) analysis of the methylation of the VHL promoter in renal carcinoma: 40 cell lines were established of Meth+ RCA cells transfected stably with VHL minigenes driven by the VHL promoter. The minigenes appeared actively transcribed and the transfected promoter was not methylated suggesting that the mechanism protecting the endogenous promoter is damaged. (4) The 3p21.3 TSG: the 700kb cosmid-P1 contig is now completely sequenced jointly by The Sanger Centre (Hinxton, UK) and The WU Genome Sequencing Center (St. Louis, USA). We are using traditional laboratory and computational methods (gene identification software) to identify the cancer genes. At the present time (Spt. 23rd) 20 new genes were isolated and investigated to identify their function and status in cancer specimen. Several important genes with potential applications in medicine were identified among these genes, they include: two new semaphorin genes (provide guidance cues in axon growth in CNS); two new genes with hyaluronidase activity, involved in angiogenesis and probably metastasis; 3 genes with SH domains; genes with RNA binding motifs; a novel MAPKAP kinase; and an unknown gene with motifs involved in cell death. About 80 Grail exons were identified and analysed for mutations or rearrangements in lung cancer. At the present time SSCP did not detect frequent mutations neither in the genes or Grail exons. The 3p12 TSG: the original large, 8mb, deletion is now narrowed by ROH and overlapping homozygous deletions, of which one is actually an intrageneic deletion that inactivates a novel gene, by sequence analysis has homology to a known TSG.