Reactive oxygen species participate in peroxynitrite-induced apoptosis in HL-60 cells

Peroxynitrite (ONOO-) is a physiological product generated by the interaction of superoxide (O-2(.-)) and nitric oxide ((NO)-N-.), We have previously shown that peroxynitrite induces apoptosis in HL-60 cells, In the present study, we demonstrated that peroxynitrite generates reactive oxygen species (ROS) in HL-60 cells, Brief exposure of HL-60 cells to ONOO- induced elevation of lucigenin chemiluminescence, indicating generation of superoxide anion. Exogenous superoxide dismutase (SOD), a scavenger of O-2(.-), fully abolished the chemiluminescence response, 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 to the apoptotic process, In addition, pre-treatment of HL-60 cells with N-acetyl-L-cysteine (15 mM), a ROS scavenger, fully scavenged peroxynitrite-elicited ROS generation and effectively inhibited ONOO--induced apoptosis, further enforcing this hypothesis, In summary, our results 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