Inhibitors of poly(ADP‐ribose) polymerase suppress nuclear fragmentation and apoptotic‐body formation during apoptosis in HL‐60 cells

The effects of 3-aminobenzamide (3ABm) and benzamide (BAm), known specific inhibitors of poly(ADP-ribose) polymerase (PARP), on actinomycin D (Act D)-induced apoptosis in HL-60 cells were examined. These inhibitors had no appreciable effect on apoptotic DNA fragmentation, chromatin condensation or PARP restriction cleavage, but clearly inhibited morphological changes, especially nuclear fragmentation and apoptotic-body formation, in a dose-dependent manner. These results suggest that the synthesis of ADP-ribose polymers is not essential for the progression of apoptotic DNA fragmentation and chromatin condensation, but is required in the processes leading to nuclear fragmentation and the subsequent apoptotic-body formation during apoptosis in HL-60 cells.