Ya'an Tibetan Tea Exerts Anti-tumor and Chemotherapy Sensitizing Effect against Human HepG2 Hepatocellular Carcinoma Cells

Chinese dark tea is post-fermented tea possessing various biological. Ya'an Tibetan tea, which is unique to China, is one of those dark tea. The purpose of this study was to observe the antiproliferative activity and chemotherapy sensitizing effect of Ya'an Tibetan tea water extract against human hepatocellular carcinoma cell line HepG2, so as to preliminarily explore the molecular mechanism of its anti-tumor effect. HepG2 cells were treated with different concentrations of Tibetan tea water extract and Tea-paclitaxel combination. The cytotoxicity was measured. The apoptotic features were detected by Hoechst 33258 fluorescence staining, flow cytometry and caspase activity assay kit of Caspase-3/8/9. Crystal violet staining method was adopted to observe the colony formation capacity of different treatment groups. The results revealed that Ya'an Tibetan tea water extract inhibited the proliferation of HepG2 cells in a time-and dose-dependent manner. Meanwhile, it also enhanced the cytotoxic effect of paclitaxel on HepG2 cells, while had no cytotoxic effect on human liver cells LO2. HepG2 cells exhibited obvious morphological changes of apoptosis after treatments. The enzyme activity of Caspase-3/8/9 in HepG2 cells were increased. Furthermore, compared with treatment alone, Tibetan tea in combination with paclitaxel significantly induced the cell apoptosis ( P < 0.05) and inhibited the colony formation capacity of HepG2 cells ( P < 0.05). This study provides an experimental basis for the further development and clinical application of Ya'an Tibetan. However, its anti-cancer potential needs further study.