CLONING TUMOR SUPPRESSOR GENES (TSG) FROM HUMAN CHROMOSOMES 3P AND 8P

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The goal of this research is to identify,clone,and characterize TSGs located on chromosomes 3p and 8p that are involved in the origin or development of major human malignancies: carcinomas of the lung, breast,kidney, and prostate.Our accomplishments this year are:(1) the novel pVHL target genes identified by us last year,namely,the carbonic anhydrases, CA9 and CA12 were further analyzed.We showed that the CA9 and CA12 genes are overexpressed in many tumor types due to the loss of VHL or other mechanisms and are involved in the control of the extracellular pH of the miliew surrounding the cells and thus create a microenvironment conducive to tumor growth and spread.Based on these finding Dr. E. Oldfield and a group of surgeons at the NIH Clinical Center initiated a prospective, non-randomized study of the effect of acetazolamide, a strong inhibitor of CAs, in patients with brain hemangioblastomas associated with brain tissue edema and cysts.Future work will focus on the role of carbonic anhydrases and othes genes in the regulation of tumor pH and its potential impact on cancer growth.(2) The 3p21.3 TSG:A subset of 19 genes found in the deletions overlap of 370-kb were subdivided by a nesting deletion into two gene sets: eight genes lying in the proximal 120-kb segment and 11 genes lying in the distal 250-kb segment. Both gene sets were analyzed extensively by manual and computational methods. Four of the 19 genes showed loss-of-expression or reduced mRNA levels in small cell (SEMA V) or non-small cell (a2d-2) or both (BLU and LUCA1) cancer cell lines. None of the 8 genes showed a frequent (>10%) mutation rate in lung cancer samples leading to conclude that with the exception of the three genes with reduced expression in this set they should be excluded as classical tumor suppressors in sporadic lung cancer. The mutation analysis of the 11 gene set is not yet completed and may reveal a TSG with homozygotic inactivation in tumors. Further mutational analysis in breast tumors and functional testing of the critical genes by gene transfer and gene disruption strategies is ongoing and should permit the identification of the putative TSG(s) among this gene set.(3) The 3p12 TSG:we discovered two new homozygous deletions in SCLC lines (250kb) removing part of the DUTT1 gene. We hypothesized that these deletions may target another cancer gene that may reside in a large intron of DUTT1. To search for this gene we prepared a sequence ready p1phage contig. We also requested the WU Sequencing Center to prepare a 1-mb BAC contig (between markers D3S3681 and D3S1604) that includes the deleted area for sequencing in the near future. (4) The 8p22 TSG:we established the intro-exon structure of the HP gene we cloned last year (GenBank # AFO26219) and are conducting mutation analyses in lung, breast, and prostate cancers. - Carcinogenesis, hereditary cancer, Lung cancer, Oncogenes, Tumor Suppressor, - Human Tissues, Fluids, Cells, etc.