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Background and Purpose Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the Chinese medicinal herb S tephaniae tetrandrae, has a long history in Chinese clinical applications to treat diverse diseases. Tetrandrine induced apoptosis or, at low concentrations, autophagy of human hepatocellular carcinoma cells. Here we have tested the effects of inhibitors of autophagy such as chloroquine, on the response to low concentrations of tetrandrine in cancer cells. Experimental Approach Cultures of several cancer cell lines, including Huh7, U251, HCT116 and A549 cells, were exposed to tetrandrine, chloroquine or a combination of these compounds. Cell viability and content of reactive oxygen species (ROS) were measured and synergy assessed by calculation of the combination index. Western blot and RT-PCR assays were also used along with fluorescence microscopy and histochemical techniques. Key Results Combinations of tetrandrine and chloroquine were more cytotoxic than the same concentrations used separately and these effects showed synergy. Such effects involved increased ROS generation and were dependent on caspase-3 but independent of Akt activity. Blockade of tetrandrine-induced autophagy with 3-methyladenine or bafilomycin-A1 induced apoptosis in cancer cells. Lack of p21 protein (p21−/− HCT116 cells) increased sensitivity to the apoptotic effects of the combination of tetrandrine and chloroquine. In a tumour xenograft model in mice, combined treatment with tetrandrine and chloroquine induced ROS accumulation and cell apoptosis, and decreased tumour growth. Conclusions and Implications The combinations of tetrandrine and chloroquine exhibited synergistic anti-tumour activity, in vitro and in vivo. Our results suggest a novel therapeutic strategy for tumour treatment. [ABSTRACT FROM AUTHOR]

Background and Purpose: Sorafenib, a potent inhibitor that targets several kinases associated with tumourigenesis and cell survival, has been approved for clinical treatment as a single agent. However, combining sorafenib with other agents improves its anti-tumour efficacy in various preclinical tumour models. ABT-263, a second-generation BH3 mimic, binds to the anti-apoptotic family members Bcl-2, Bcl-xL and Bcl-w, and has been demonstrated to enhance TNFSF10 (TRAIL)-induced apoptosis in human hepatocarcinoma cells. Hence, we investigated the effects of ABT-263 treatment combined with sorafenib.Experimental Approach: The effects of ABT-263 combined with sorafenib were investigated in vitro, on cell viability, clone formation and apoptosis, and the mechanism examined using western blot and flow cytometry. This combination was also evaluated in vivo, in a mouse xenograft model; tumour growth, volume and weights were measured and a TUNEL assay performed.Key Results: ABT-263 enhanced sorafenib-induced apoptosis while sparing non-tumourigenic cells. Although ABT-263 plus sorafenib significantly stimulated intracellular reactive oxygen species production and subsequent mitochondrial depolarization, this was not sufficient to trigger cell apoptosis. ABT-263 plus sorafenib significantly decreased Akt activity, which was, at least partly, involved in its effect on apoptosis. Bax and p21 (CIP1/WAF1) were shown to play a critical role in ABT-263 plus sorafenib-induced apoptosis. Combining sorafenib with ABT-263 dramatically increased its efficacy in vivo.Conclusion and Implications: The anti-tumour activity of ABT-263 plus sorafenib may involve the induction of intrinsic cell apoptosis via inhibition of Akt, and reduced Bax and p21 expression. Our findings offer a novel effective therapeutic strategy for tumour treatment. [ABSTRACT FROM AUTHOR]

Background and purpose Sorafenib, a potent inhibitor that targets several kinases associated with tumourigenesis and cell survival, has been approved for clinical treatment as a single agent. However, combining sorafenib with other agents improves its anti-tumour efficacy in various preclinical tumour models. ABT-263, a second-generation BH3 mimic, binds to the anti-apoptotic family members Bcl-2, Bcl-xL and Bcl-w, and has been demonstrated to enhance TNFSF10 (TRAIL)-induced apoptosis in human hepatocarcinoma cells. Hence, we investigated the effects of ABT-263 treatment combined with sorafenib. Experimental Approach The effects of ABT-263 combined with sorafenib were investigated in vitro, on cell viability, clone formation and apoptosis, and the mechanism examined using western blot and flow cytometry. This combination was also evaluated in vivo, in a mouse xenograft model; tumour growth, volume and weights were measured and a TUNEL assay performed. Key Results ABT-263 enhanced sorafenib-induced apoptosis while sparing non-tumourigenic cells. Although ABT-263 plus sorafenib significantly stimulated intracellular reactive oxygen species production and subsequent mitochondrial depolarization, this was not sufficient to trigger cell apoptosis. ABT-263 plus sorafenib significantly decreased Akt activity, which was, at least partly, involved in its effect on apoptosis. Bax and p21 ( CIP1/WAF1) were shown to play a critical role in ABT-263 plus sorafenib-induced apoptosis. Combining sorafenib with ABT-263 dramatically increased its efficacy in vivo. Conclusion and Implications The anti-tumour activity of ABT-263 plus sorafenib may involve the induction of intrinsic cell apoptosis via inhibition of Akt, and reduced Bax and p21 expression. Our findings offer a novel effective therapeutic strategy for tumour treatment. [ABSTRACT FROM AUTHOR]