RESUMEN
AIM: Glycogen synthase kinase 3ß (GSK-3ß) plays a crucial role in hepatic biology, including liver development, regeneration, proliferation and carcinogenesis. In this study we investigated the role of GSK-3ß in regulation of growth of hepatic oval cells in vitro and in liver regeneration in partially hepatectomized rats. METHODS: WB-F344 cells, the rat hepatic stem-like epithelial cells, were used as representative of oval cells. Cell viability was examined using a WST-8 assay. The cells were transfected with a recombinant lentivirus expressing siRNA against GSK-3ß (GSK-3ßRNAiLV) or a lentivirus that overexpressed GSK-3ß (GC-GSK-3ßLV). Adult rats underwent partial (70%) hepatectomy, and liver weight and femur length were measured at d 7 after the surgery. The expression of GSK-3ß, phospho-Ser9-GSK-3ß, ß-catenin and cyclin D1 was examined with immunoblotting assays or immunohistochemistry. RESULTS: Treatment of WB-F344 cells with the GSK-3ß inhibitor SB216763 (5 and 10 µmol/L) dose-dependently increased the levels of phospho-Ser9-GSK-3ß, but not the levels of total GSK-3ß, and promoted the cell proliferation. Knockout of GSK-3ß with GSK-3ßRNAiLV increased the cell proliferation, whereas overexpression of GSK-3ß with GC-GSK-3ßLV decreased the proliferation. Both SB216763 and GSK-3ßRNAiLV significantly increased the levels of ß-catenin and cyclin D1 in the cells, whereas GSK-3ß overexpression decreased their levels. In rats with a partial hepatectomy, administration of SB216763 (2 mg/kg, ip) significantly increased the number of oval cells, the levels of phospho-Ser9-GSK-3ß, ß-catenin and cyclin D1 in liver, as well as the ratio of liver weight to femur length at d 7 after the surgery. CONCLUSION: GSK-3ß suppresses the proliferation of hepatic oval cells by modulating the Wnt/ß-catenin signaling pathway.