Identification of candidate liver tumor suppressor genes from human 11p11.2-p12

We have previously described a functional model for identification of human liver tumor suppressor genes in which human chromosome I I was introduced into rat liver epithelial, tumor cell lines via microcell-mediated chromoso me transfer, producing microcell hybrid (MCH) cell lines that exhibit suppr ession of tumorigenicity in vivo. Chromosome deletion mapping studies ident ified a 950-kb region of 11p11.2-p12 that was retained in all suppressed MC H cell lines, suggesting that this region may harbor one or more genes with liver tumor suppressor function. In this study, we generated a comprehensi ve transcription map of the 11p11.2-p12 liver tumor suppressor region throu gh examination of 142 expressed sequence tag (EST) markers among a group of suppressed MCH cell lines. Of 142 ESTs examined, 19 were localized within the 11p11.2-p12 liver tumor suppressor region. RT-PCR analysis of gene expr ession for these 19 ESTs among an index panel of suppressed MCH cell lines (n = 3) identified 11 potential candidate liver tumor suppressor genes. Exa mination of candidate gene expression among six additional suppressed MCH c ell lines reduced the numbers of potential candidate genes to three (stSG30 184, stSG10014, and stSG29748). Northern blot analysis of suppressed, MCH c ell lines and derived tumor cell lines suggested stSG30184 as the best cand idate liver tumor suppressor gene. The 3.7 kb stSG30184 transcript was expr essed by all suppressed MCH cell lines, but expression was extinguished coo rdinately with reexpression of tumorigenicity by these cells, consistent wi th a tumor suppressor gene. Subsequent characterization of this EST indicat es that it is a novel transcript with expression in a broad range of tissue types. Further characterization of the genes identified in this study will provide a greater understanding of their role in the molecular pathogenesi s of neoplastic liver disease. (C) 2002 Wiley-Liss, Inc.