The activation of caspase cascades was involved in TCS-induced cell apoptosis.
A. After treatment with TCS at the indicated concentrations, cells were harvested and protein levels of caspase-8, caspase-9, caspase-3, and PARP were determined by western blotting. Right panel, quantitative data from two independent experiments. Lower panel, The caspase-8 and caspase-9 activities were determined by ELISA kits. Asterisk, p<0.05 compared with control. B. TCS increased the number of tumor cells undergoing mitochondrial membrane depolarization. Cells were treated with TCS at the indicated concentrations for 24 h, and flow cytometry analysis of the mitochondrial membrane depolarization was carried out after JC-1 staining. C. Z-VAD-FMK pretreatment retarded TCS-induced cell apoptosis. After different treatments as indicated at the bottom of the histogram, cells were harvested, stained with Annexin V-PI, and processed for flow cytometry. Asterisk, p<0.05 compared with control.