Activation of caspase-3 during bacterial redox protein azurin-induced apoptosis in U2OS cells

AIM: To study whether caspase-3,8 is activated during azurin-induced apoptosis in U2OS cells. METHODS: AnnexinV /PI method was used to detect apoptosis. The changes of procaspase-3 were analyzed by Western blot, the changes of caspase-3 mRNA were detected by semi-quantitative RT-PCR, and caspase-3 relative activity was determined by colorimetric assay. RESULTS: After U2OS cells were treated with 0, 25, 50, 100, 200, 500 mg/L azurin for 24 h, respectively, the level of procaspase-3 protein decreased and the level of caspase-3 mRNA increased as azurin concentration increased. When the cells were treated with 100 mg/L azurin for 6, 12, 24, 48 h , respectively, the caspase-3 activity began to rise from 6 h,reached the peak at 24 h,and was still higher than the control group at 48 h ( P 0 01). After the cells were treated with azurin at different concentrations for 24 h, caspase-3 activity increased in a concentration -dependent manner. CONCLUSION: Caspase-3 is activated and plays an important role in azurin-induced apoptosis in U2OS cells. [