Anticancer effect of 20(S)-ginsenoside Rh2 on HepG2 liver carcinoma cells: Activating GSK-3β and degrading β-catenin

20(S)-ginsenoside Rh2 [(S)Rh2] possesses potential to prevent cancer in vitro as well as in vivo, but the underlying mechanism is still unknown. First, we infected HepG2 cells with lentivirus which carries β-catenin. We detected the pharmacological effects of (S)Rh2 on HepG2 and HepG2-β-catenin cells and found that the IC50 of (S)Rh2 exposure on HepG2-β-catenin cells was higher than HepG2 cells. Flow cytometry (FCM) indicated that (S)Rh2 could be arrested in G0/G1 phase and induce early apoptosis in HepG2 and HepG2-β-catenin cells. Second, ELISA kit was used to check the activity of glycogen synthase kinase-3β (GSK-3β), which was upregulated by (S)Rh2. GSK-3β inhibitor BIO, was used to verify that (S)Rh2 activated GSK-3β. PCR and western blotting results indicated that (S)Rh2 could degrade the expression of β-catenin, which combined with TCF in the nucleus and activate transcription of Wnt target genes, such as Bax, Bcl-2, cyclin D1, MMP3, which were checked by chromatin immunoprecipitation (ChIP), PCR and western blotting. The results showed that the expression of Bax mRNA and proteins increased, while the cyclin D1, Bcl-2, MMP3 mRNA and proteins were downregulated in HepG2 and HepG2-β-catenin cells which was induced by (S)Rh2. By contrast, with the HepG2-β-catenin + (S)Rh2 group, the expression of other mRNA and proteins in HepG2 + (S)Rh2 group changed significantly. In vivo, experiments were performed using a nude mouse xenograft model to investigate the (S)Rh2 effect. So these results suggested that (S)Rh2 could suppress proliferation, promote apoptosis and inhibit metastasis of HepG2, decrease weight of tumor by downregulating β-catenin through activating GSK-3β and the pharmacological effect of (S)Rh2 on HepG2 cells might be weakened by overexpression of β-catenin.