Arsenic Trioxide Induces Apoptosis of HL-60 Cells via Activation of Intrinsic Caspase Protease with Mitochondrial Dysfunction.

PURPOSE Arsenic trioxide (As2O3) was introduced into the treatment of refractory or relapsed acute promyelocytic leukemia and showed a striking effectiveness in China and United States multicenter study. However, the mechanistic basis for the carcinogenic or therapeutic effects of arsenics is still poorly understood. So, this study is performed to determine whether As2O3 induces apoptosis through intrinsic caspase cascades in acute promyelocytic leukemia HL-60 cells. MATERIALS AND METHODS HL-60 cells were treated with As2O3 to investigate apoptosis through signaling of caspase cascades and mitochondrial dysfunction. RESULTS As2O3 (>0.5 uM) decreased the viability of HL-60 cells in a dose-dependent manner, which was revealed as apoptosis shown chromatin condensation and ladder pattern DNA fragmentation. As2O3 increased the catalytic activity of caspase family cysteine proteases including caspase-3 and -9 proteases. Consistently, PARP, an intracellular biosubstrate of caspase-3 protease, was cleaved from 116 kDa to 85 kDa fragments. It also induced the change of mitochondrial membrane potential. Morever, As2O3 resulted in the increase of Bak. CONCLUSION These data suggest that As2O3 induces apoptosis of HL-60 cells through activation of intrinsic caspase protease with mitochondrial dysfunction.