CHANGES IN GENE-EXPRESSION DURING THE GROWTH ARREST OF HEPG2 HEPATOMA-CELLS INDUCED BY REDUCING AGENTS OR TGF-BETA-1

The growth of hepatoma cells can be inhibited by treatment with TGF be ta 1 or with exogenous reducing agents. To gain information on the mol ecular mechanisms underlying growth arrest, we visualized and compared gene expression profiles of proliferating ver sus non proliferating H epG2 cells by computer-assisted gene fishing, an improved technique of RNA fingerprinting that allows the selective amplification of coding regions within transcripts. While many transcripts are selectively reg ulated by either treatment, a set of bands appear to be coordinately r egulated by 2ME and TGF beta 1, suggesting their possible involvement in the mechanisms of growth arrest. Display tags corresponding to 18 d ifferentially expressed genes were cloned and, in most cases, identifi ed as known genes or, more frequently, as their homospecific/cross-spe cific homologues. A novel member of the kinesin superfamily was identi fied amongst the genes induced by both 2ME and TGF beta 1. This gene, KIF3C, is upregulated in several cell lines undergoing growth arrest. Taken together, our findings show that computer-assisted gene fishing is a powerful tool for the identification and cloning of genes involve d in the control of cell proliferation and indicate that extracellular reducing agents can regulate cell growth through modulation of gene e xpression.