Toosendanin Inhibits Hepatocellular Carcinoma Cells by Inducing Mitochondria-dependent Apoptosis

Toosendanin, a triterpenoid derivative isolated from Melia toosendan Sieb. et Zucc., possesses different pharmacological effects in humans and an important value in agriculture. As indicated by previous reports, the molecular mechanisms of toosendanin's anticancer effects remain poorly clarified. In this study we used both in vivo and in vitro models to investigate the anti-cancer effects of toosendanin and their possible molecular mechanisms. In the in vitro experiment, human hepatocellular carcinoma cell lines [SMMC-7721 (p53+) and Hep3B (p53-)] were coincubated with toosendanin of different concentrations (0.1 similar to 0.9 mu M). Anti-proliferation effects were observed to be in a dose- and time-dependent manner. The IC(50) of TSN treated after 72 h for SMMC-7721 and Hep3B cells was 0.5 mu M and 0.9 mu M, respectively. Results from morphological analysis, annexin V staining, detection of caspases activity, and expressions of Bcl-2, Bax, and Fas indicated that the anticancer effects of toosendanin were associated with its induction of apoptosis via the mitochondria-dependent pathway in p53- and p53+ hepatocellular carcinoma cells. In the in vivo experiment, BALB/c mice were s.c. inoculated with mouse hepatocellular carcinoma H(22) cells. Both high-dose (0.69 mg/kg) and low-dose (0.173 mg/kg) toosendanin administrated intra-peritoneally resulted in strongly suppressive effects on the tumorigenicity and apoptotic response. Results from the immunohistochemistry for Bcl-2, Bax, as well as for Fas showed that the anticancer effects of toosendanin were induced via apoptosis in a mitochondria-dependent manner, which confirmed the findings in the in vitro experiment. The findings above demonstrate that toosendanin possesses strong anticancer effects in vivo and in vitro via inducing mitochondria-dependent apoptosis in hepatocellular carcinoma cells.