The antitumor effects of ginsenoside Rg3 have been reported in several kinds of human malignant tumors. The purpose of this study was to investigate whether ginsenoside Rg3 can inhibit the growth of human hepatocellular carcinoma cell lines and to discuss the possible molecular mechanism(s). We cultured the human hepatocellular carcinoma cell lines, SMMC-7721 and HepG2. The cells were treated with different concentrations of ginsenoside Rg3 (0, 25, 50, 75 and 100 µg/ml), and the cell proliferation was detected by MTT assay at the 12, 24, 36 and 48 h time-points. Flow cytometry experiments were carried out to investigate the effect of Rg3 on cell apoptosis after the cells had been treated with Rg3 (50 and 100 µg/ml) for 24 and 48 h. The expression levels of caspase-3, bax and bcl-2 in Rg3-treated cells (100 µg/ml, 48 h), as well as normal cells were detected through real-time PCR experiments. MTT assay showed that the inhibition rate of cell proliferation in the Rg3 groups was significantly higher compared to the control groups in both the SMMC-7721 and HepG2 cell lines, and the inhibition rate increased with increasing Rg3 concentrations and duration of treatment. Flow cytometry analysis demonstrated that the Rg3 groups had a significantly higher cell apoptotic rate compared to the control groups in both the SMMC-7721 and HepG2 cell lines, and that the effect of Rg3 on cell apoptosis occurred in a concentration- and time-dependent manner, as was also shown by the MTT assay. Real-time PCR analysis showed that the gene expression levels of caspase-3 and bax were significantly enhanced in the Rg3 groups compared to the control groups in both the SMMC-7721 and HepG2 cell lines, but the gene expression level of bcl-2 was significantly inhibited. These results indicate that ginsenoside Rg3 can effectively inhibit the growth of human hepatocellular carcinoma cell lines by inhibiting cancer cell proliferation and promoting cancer cell apoptosis, and it may promote cancer cell apoptosis via the endogenous mitochondrial-mediated caspase-dependent apoptotic pathway.
