Caspase inhibition and N6-benzyladenosine-induced apoptosis in HL-60 cells

As an extension of our recently published work (Mlejnek and Kuglík [2000] J. Cell. Biochem. 77:6-17), the role of caspases in N(6)-benzylaminopurine riboside (BAPR)-induced apotosis in HL-60 cells was evaluated in this study. Here, BAPR-induced Apoptosis was accompanied by activation of Caspase-3 and caspase-9. However, when these caspases were selectively inhibited, the progression of BAPR-induced Apoptosis was not markedly affected. Besides that, activation of Caspase-3 and caspase-9 was found to be rather late event in apoptotic process. These results suggested that other caspases might be critically implicated. Indeed, pan-specific Caspase Inhibitor, Z-VAD-FMK, completely prevented DNA cleavage and apoptotic bodies formation. However, Z-VAD-FMK failed to prevent cell death and it was incapable to fully counteract the main apoptotic hallmark-chromatin condensation. Finally, our data indicate that cellular decision between Apoptosis and necrosis is made upon the availability of both Caspase proteases and intracellular ATP.