Synergistic Combinations of Tanshinone IIA and Trans-resveratrol Toward Cisplatin-comparable Cytotoxicity in HepG2 Human Hepatocellular Carcinoma Cells

Aim: To determine the combinative effects of tanshinone IIA (Tan IIA) and trans-resveratrol (Resv) on cytotoxicity, apoptosis, cell-cycle arrest and DNA fragmentation in HepG2 human liver cancer cells. Materials and Methods: Cytotoxicity was detected by the cell proliferation and cytotoxicity WST-1 assay. Cell-cycle arrest and apoptosis were determined using flow cytometry analysis. DNA fragments were separated by gel electrophoresis. Results: Tan IIA and Resv at mixture ratios of 1/2:1/2 and 1/3:2/3 exerted synergistic cytotoxicity comparable to that of cisplatin. Elevated proportions of sub-G 1 and apoptotic cells were respectively found in the combinative treatments in comparison with hypothetic values of additive effects. Moreover, a more intensive pattern of apoptotic DNA fragmentation was visualized in combined treatments than in individual ones. Conclusion: Combining Tan IIA and Resv causes synergistic cisplatin-comparable, cytotoxicity and robustly induces apoptosis, sub-G1 cell cycle arrest and DNA fragmentation. This study provides evidence supporting further pre-clinical investigations of the combinational synergism. Liver cancer is the second most common cause of cancer- related death worldwide (1). Although more than 80% of cases of this disease occur in less developed or developing countries of Asia and Africa (1), new cases of liver cancer have increased remarkably in America, Japan and some areas of Europe over the past two decades (2). Epidemiological and clinical statistics indicate the difficulty of managing liver cancer, with fatalities from the disease increasing from 463,000 in 1990 to 598,000 in 2002, to 695,900 in 2008 and 752,100 in 2010 (3-5). Despite increased clinical effectiveness of current and conventional treatments through surgery and chemotherapy, the relative 5-year survival rate is as low as 15% and the chemotherapeutic drugs used in treatment (e.g., cisplatin) are associated with significant negative side effects. Even though the cytotoxic activity of cisplatin is superior to 5-fluorouracil (5-FU) and paclitaxel in the human liver cancer cell line HepG2 (6), its use is limited by side-effects including hemolytic anemia and nephro-, neuro-, oto- and myelotoxicity. Thus, enormous efforts have been invested to develop potent antitumor drugs with fewer side-effects. Among many strategies, compounds isolated from traditional medicinal plants have attracted extensive interest.