Lithocarpus polystachyus (Sweet Tea) water extract promotes human hepatocytes HL7702 proliferation through activation of HGF/AKT/ERK signaling pathway.

ABSTRACT

Objective: Sweet Tea (ST), derived from the leaves of Lithocarpus polystachyus, is a Chinese folk medicine with wide pharmacological activities. However, the promotive effects of ST water extract on hepatocytes proliferation and its underlying mechanism remains still unknown. In the present study, the beneficial effects of ST water extract on human hepatocytes and its possible mechanism were investigated. Methods: MTT assay was used to detect the safety range of ST; HL7702 cells were divided into four groups control group, ST low- (50 µg/mL), medium- (200 µg/mL) and high-concentration (800 µg/mL) groups; BrdU ELISA and EDU staining were used to observe DNA content and cell proliferation; Moreover, flow cytometry was applied to analyze the distribution of cell cycle. Furthermore, the expression of cyclin D1, CDK4, HGF/c-Met, Akt, Erk1/2 were detected by Western blot. Results: It was found that ST water extract concentration-dependent promoted human hepatocytes HL7702 cell proliferation within 72 h through accumulating the cells in S phase and G2/M phase. Furthermore, ST water extract up-regulated expression of Cyclin D1 and CDK4 proteins. Moreover, ST water extract not only increased HGF expression and phosphorylation of c-Met level, but also activated the phosphorylation levels of AKT, ERK1/2. Interestingly, both of AKT inhibitor A6730 and ERK1/2 inhibitor U0126 reversed the promotive effects of ST water extract, which further confirmed that activation of AKT and ERK1/2 were involved. Conclusion: The findings reveal that ST water extract promoted HL7702 cells proliferation through the stimulation of cell cycle mediated by activating the AKT- and ERK1/2-related pathway.