Cinobufacini, an aqueous extract from Bufo bufo gargarizans Cantor, induces apoptosis through a mitochondria-mediated pathway in human hepatocellular carcinoma cells

Aim of the study: Cinobufacini (Huachansu), an aqueous extract from the skin and parotid venom glands of Bufo bufo gargarizans Cantor, is a traditional Chinese medicine widely used in clinical cancer therapy in China. The present study sought to investigate the possible signaling pathway implicated in cinobufacini-induced apoptosis in the hepatocellular carcinoma cell lines HepG(2) and Bcl-7402. Materials and methods: The effects of cinobufacini on cell proliferation of HepG2 and Bel-7402 cells were evaluated by 3-[4,5-dimethylthiazol-2-y1]-2,5-diphenyl-tetrazolium bromide (MU) assays. Cell apoptosis was detected by Hoechst 33258 staining and flow cytometry analysis. The mitochondrial membrane potential (Delta psi m) and caspase-9 and -3 activity were detected using MitoCapture reagent staining and colorimetric assays, respectively. The expression of apoptosis-related proteins and release of cytochrome c were assessed by Western blot analysis. Results: Cinobufacini significantly inhibited cell proliferation of both cell lines in a dose- and time-dependent manner. Marked changes in apoptotic morphology and apoptosis rates were clearly observed after cinobufacini treatment. The protein expression of Bax increased whereas that of Bcl-2 decreased, leading to an increase in the Bax/Bcl-2 ratio. Subsequently, cinobufacini disrupted the mitochondrial membrane potential (Delta psi m) and resulted in the release of cytochrome c, activation of both caspase-9 and -3, and cleavage of poly (ADP-ribose) polymerase (PARP). Conclusion: The present study indicated that cinobufacini can induce apoptosis of HepG2 and Bcl-7402 cells through a mitochondria-mediated apoptosis pathway. (C) 2010 Elsevier Ireland Ltd. All rights reserved.