Ethylacetate extract from Tetrastigma hemsleyanum inhibits proliferation and induces apoptosis in HepG2 and SMMC-7721 cells

Purpose: This study aimed to investigate the effect of ethylacetate extract from Tetrastigma hemsleyanum (EET) on the proliferation and apoptosis of HepG2 and SMMC-7721 cells and determine the underlying mechanisms.

Materials and methods: HepG2 and SMMC-7721 cells were cultured in vitro until the exponential growth phase and then treated with different concentrations of EET for 24 h. We performed a colony forming assay to determine colony forming ability, CCK8 assay to detect cell proliferation, Annexin V-FITC/PI double staining to analyze cell apoptosis, and Western blot to measure the protein expression of Caspase-3, Bcl-2, and Bax.

Results: EET significantly inhibited the proliferation of HepG2 and SMMC-7721 cells in a concentration- and time-dependent manner (P<0.05). After treatment with 0, 50, 100, 150, 200, and 250 μg/mL EET for 24 h, HepG2 the proliferation rates were 100.00%±0.00%, 90.33%±1.76%, 67.67%±0.88%, 47.33%±0.88%, 37.00%±0.00%, and 30.33%±0.67%, respectively, and 100.00%±0.00%, 18.25%±1.05%, 19.99%±0.59%, 23.42%±0.46%, 29.70%±0.79%, and 29.8%±0.41% for SMMC-7721 cells, respectively. After treatment with 0, 50, 100, 150, 200, and 250 μg/mL EET for 24 h, the apoptotic rates were 11.08%±0.72%, 27.44%±0.51%, 32.92%±0.41%, 26.20%±0.47%, 22.92%±0.24%, and 55.60%±0.08%, for HepG2 cells, respectively, and 59.18%±0.17%, 41.24%±2.05%, 52.54%±0.39%, 50.54%±1.08%, and 57.44%±1.93% for SMMC-7721 cells, respectively. Compared with the treatment groups, the control group showed a significantly lower apoptotic rate (47.91%±1.09%, P<0.05). EET at the different concentrations downregulated the protein expression of Caspase-3 in HepG2 cells and upregulated it in SMMC-7721 cells; it also downregulated the protein expression of Bcl-2 in HepG2 and SMMC-7721 cells and upregulated the protein expression of Bax in HepG2 and SMMC-7721 cells.

Conclusion: These findings suggest that EET exerts antiproliferative and proapoptotic effects against HepG2 and SMMC-7721 cells mediated by downregulation or upregulation of Caspase-3 expression. Our study may help to develop EET for the pharmacological treatment of hepatoblastoma or hepatocellular carcinoma.