REACTIVE OXYGEN SPECIES PARTICIPATE IN PEROXYNITRITE-INDUCED APOPTOSIS IN HL-60 CELLS

Peroxynitrite (ONOO-) is a physiological product generated by the inte raction of superoxide (O-2(.-)) and nitric oxide ((NO)-N-.), We have p reviously shown that peroxynitrite induces apoptosis in HL-60 cells, I n the present study, we demonstrated that peroxynitrite generates reac tive oxygen species (ROS) in HL-60 cells, Brief exposure of HL-60 cell s to ONOO- induced elevation of lucigenin chemiluminescence, indicatin g generation of superoxide anion. Exogenous superoxide dismutase (SOD) , a scavenger of O-2(.-), fully abolished the chemiluminescence respon se, further supporting this notion. Following O-2(.-) generation, the accumulation of hydrogen peroxide (H2O2) was observed, The addition of SOD exacerbated but that of catalase attenuated peroxynitrite-induced DNA fragmentation, suggesting that this H2O2 production contributes t o the apoptotic process, In addition, pre-treatment of HL-60 cells wit h N-acetyl-L-cysteine (15 mM), a ROS scavenger, fully scavenged peroxy nitrite-elicited ROS generation and effectively inhibited ONOO--induce d apoptosis, further enforcing this hypothesis, In summary, our result s suggest that ONOO--stimulated ROS formation may serve as a mechanism for the propagation of peroxynitrite-mediated apoptotic cell death in an intact cell system. (C) 1997 Academic Press