Identification of three 11p11.2 candidate liver tumor suppressors through analysis of known human genes

We have previously mapped a liver tumor suppressor locus to human chromosome 11p11.2-p12 using a functional model of tumor suppression. Using this model system, we have employed a candidate gene approach to identify potential liver tumor suppressor genes. Thirty-eight known genes have been positioned in human 11p11.2-p12 by the Human Genome Project. Here we show that four of these genes (guanine nucleotide binding protein gamma 3; mitochondrial carrier homolog 2; p53-induced protein (PIG11), and pRDI-BF1-rIZ1 domain containing 11) localized to the minimal liver tumor suppressor region within 11p11.2-p12. In fact, all of these genes mapped to human 11p11.2, allowing refinement of the liver tumor suppressor region to this cytogenetic band. Three of the four genes (mitochondrial carrier homolog 2, PIG11, and pRDI-BF1-rIZ1 domain containing 11) were uniformly expressed by an index panel of suppressed microcell hybrid cell lines, identifying them as candidate liver tumor suppressor genes. In a preliminary analysis of four human hepatocellular carcinoma cell lines (HepG2, Hep3B, SNU398, and SNU449), the transcript for PIG11 was lost or significantly decreased in two of these cell lines (HepG2 and Hep3B), suggesting the potential involvement of PIG11 in some human hepatocellular carcinomas. The results of this study extended our previous knowledge of genes located in the minimal liver tumor suppressor region of human 11p11.2 and identified several candidate liver tumor suppressor genes from this region. Further characterization of these candidates will provide new insight into the role of human 11p11.2 in the molecular pathogenesis of human liver cancer.