Chan Su is a traditional Chinese medicine prepared from the dried white secretion of the auricular and skin glands of toads, and has been used as an oriental drug for the treatment of a number of diseases, including cancer. In this study, the potential of Chan Su (skin of Venenum Bufonis) to induce apoptosis in human lung carcinoma A549 cells was investigated. Treatment of A549 cells with skin of Venenum Bufonis resulted in the inhibition of cell growth and viability and the induction of apoptosis, which was shown by trypan blue counts, MTT assay, DAPI staining and flow cytometry analysis. The increase in apoptosis that was induced by skin of Venenum Bufonis was correlated with down-regulation of anti-apoptotic Bcl-2 expression, up-regulation of pro-apoptotic Fas ligand and death receptor 4, and a decrease in the mitochondrial membrane potential. Skin of Venenum Bufonis treatment induced the proteolytic activation of caspases and a concomitant degradation of poly(ADP-ribose)-polymerase and beta-catenin protein. Cleavage of Bid and a down-regulation of the inhibitor of apoptosis family proteins were also observed in skin of Venenum Bufonis-treated A549 cells. Data from this study indicates that SVB induces the apoptosis of A549 cells through a signaling cascade of death receptor-mediated extrinsic and mitochondria-mediated intrinsic caspase pathways.

Abstract. The root of Panax notoginseng is highly valued and commonly used in Oriental medicine. Although recent experimental data have revealed the proapoptotic potency of P. notoginseng extracts, the underlying molecular mechanisms of this apoptotic activity have not yet been studied in detail. In the present study, the effects of the water extract of P. notoginseng (WEPN) on the growth of human lung carcinoma cells were investigated. It was found that the exposure of A549 and NIC-H460 cells to WEPN resulted in growth inhibition and the induction of apoptosis in a dosedependent manner. The WEPN treatment induced the upregulation of pro-apoptotic Bax, downregulation of antiapoptotic Bcl-2 expression and loss of mitochondrial membrane potential (MMP), which was associated with the proteolytic activation of caspases and the concomitant degradation of poly(ADP ribose) polymerase (PARP) protein. However, the caspase-3-specific inhibitor z-DEVD-fmk blocked PARP degradation and increased the survival rate of WEPN-treated cells. Moreover, the activity of Akt was downregulated in WEPN-treated cells and the phosphatidylinositol-3 kinase (PI3K)/Akt inhibitor LY294002 sensitized the cells to WEPN-induced apoptosis through enhancing the activation of caspase-3 and loss of MMP. The results indicated that the major regulators of WEPN-induced apoptosis in human lung carcinoma cells are the Bcl-2 family and caspase-3, which are associated with mitochondrial dysfunction and dephosphorylation of the Akt signaling pathway.