Regulation of hepatic oval cell proliferation by adenoviral mediated hepatocyte growth factor gene transfer and signal transduction inhibitors

BACKGROUND/AIMS: To rescue patients with severe liver injury, it is critical to develop the efficient regulatory system of hepatic stem cell proliferation in vitro. Our aims are to examine whether combination of adenovirus-mediated hepatocyte growth factor (HGF) gene transfer with signal transduction inhibitors can regulate cell proliferation of oval cells. METHODOLOGY: We examined the effects of treatment with adenoviral mediated HGF gene transfer and signal transduction inhibitors including LY294002, rapamycin and U0126 on proliferation OC/CDE22 hepatic oval cells and expression of signal transduction molecules. RESULTS: Infection with pAxCAHGF expanded the cells by 8-fold at 2 days, by 18-fold at 3 days and by 55-fold at 4 days. The addition of inhibitors inhibited pAxCAHGF-induced cell proliferation by LY294002 or rapamycin (P < 0.01, each). U0126 also inhibited growth of hepatic oval cells (P < 0.01). pAxCAHGF treatment induced phosphorylation of AKT. Treatment with rapamycin resulted in enhanced phosphorylation of AKT, and phosphorylation of AKT was induced by pAxCAHGF plus U0126. CONCLUSIONS: Autocrine expression of HGF with signal transduction inhibitors can regulate proliferation of OC/CDE22 hepatic oval cells. In addition, the AKT pathway is important for HGF-stimulated hepatic oval cell proliferation.