Leptin facilitates the proliferation activity of hepatoma cells via regulating cell cycle proteins

Objective:To explore the effect of leptin on proliferation of human hepatocellular carcinoma cells Huh 7 and its probable molecular mechanism.Methods:The human hepatocellular carcinoma cells Huh 7 cultured in vitro was treated with leptin at different concentrations.The proliferation of the cells was measured by MTT assay.The cell cycle was monitored by flow cytometry analysis(FCM).The expression of cell cycle regulatory proteins Cyclin D1 and P21waf1 were determined by immunocytochemistry and imageanalysis system,and real-time quantitative PCR.Results:Leptin significantly raised the proliferation rate of Huh 7 cells.The effect was dose and time-depended partly.Leptin promoted Huh 7 cells in entering the S phase from the G0/G1 phase.mRNA of Cyclin D1 in the leptin treated Huh 7 cells was increased,as compared with that in the control cells(P0.01).In contrast,P21waf1 mRNA in the leptin treated Huh 7 cells was decreased as compared with that in the control(P0.01).Cyclin D1 protein expression in the Huh 7 cells treated with 100 ng/ml leptin was also significantly increased compared with the controls(P0.01) while the P21waf1 protein expression was suppressed(P0.01). Conclusion: Leptin can stimulate Cyclin D1 expression and inhibit P21waf1 expression,promote Huh 7cells entering the S phase from the G0/G1 phase,and facilitate cell proliferation.