Involvement of Bax and caspase-3 activation in Chan-Su-induced ASTC-a-1 cell apoptosis

Chan-Su (CS), a traditional Chinese medicine, is one of the most potent Chinese medicines currently used in cancer chemoprevention and treatment. However, the molecular mechanism of CS-induced-apoptosis is still unclear. This study investigated the molecular mechanism of CS-induced apoptosis using fluorescence resonance energy transfer (FRET) and confocal fluorescence microscope techniques. CS dose-dependently inhibited cell viability cytotoxicity, which was assayed by Cell Counting Kit (CCK-8) and Hoechst33258 staining. Bax translocation to mitochondria was observed in single living cell transfected with GFP-Bax plasmid. The mitochondrial membrane potential (ΔΨ $_{m}$ ) loss was also measured in CS-treated cells. And ASTC-a-1 cell expressed stably with SCAT3 plasmid was used to examine if caspase-3 was activated by CS. z-VAD-fmk, a broad-caspase spectrum inhibitor, was found to significantly reduce the inhibition of CS on the cell viability. Overall, our data demonstrated that CS induced ASTC-a-1cells apoptosis in a dose-dependent manner, and Bax, caspase-3 and mitochondrial stress were involved in CS-induced apoptosis. Our findings extend the knowledge about the cellular signaling mechanisms mediating CS-induced apoptosis.