Antioxidant enzyme inhibitors enhance nitric oxide-induced cell death in U937 cells.
Nitric oxide (NO), a radical species produced by many types of cells, is known to play a critical role in many regulatory processes, yet it may also participate in collateral reactions at higher concentrations, leading to cellular oxidative damage. The protective role of antioxidant enzymes against NO-induced oxidative damage in U937 cells was investigated in control and cells pre-treated with diethyldithiocarbamic acid, aminotriazole, and oxlalomalate, specific inhibitors of superoxide dismutase, catalase, and NADP(+)-dependent isocitrate dehydrogenase, respectively. Upon exposure to 1 mM S-nitroso-N-acetylpenicillamine (SNAP), the nitric oxide donor, to U937 cells, the viability was lower and the protein oxidation, lipid peroxidation and oxidative DNA damage reflected by an increase in 8-hydroxy-2'-deoxyguanosine, were higher in inhibitor-treated cells as compared to control cells. We also observed the significant increase in the endogenous production of reactive oxygen species, as measured by the oxidation of 2'7'-dichlorodihydrofluorescin as well as the significant decrease in the intracellular GSH level in inhibitor-treated U937 cells upon exposure to NO. Upon exposure to 0.2 mM SNAP, which induced apoptotic cell death, a clear inverse relationship was observed between the control and inhibitor-treated U937 cells in their susceptibility to apoptosis. These results suggest that antioxidant enzymes play an important role in cellular defense against NO-induced cell death including necrosis and apoptosis.
Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Taegu 702-701, South Korea.
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Yang
J-W
JW
Park
D000640:Amitrole / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002374:Catalase / Q000037:antagonists & inhibitors / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004050:Ditiocarb / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D034921:Lamin Type B / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010070:Oxalates / Q000494:pharmacology; D010084:Oxidation-Reduction; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000037:antagonists & inhibitors / Q000378:metabolism; D020298:U937 Cells
D004791:Enzyme Inhibitors; D034921:Lamin Type B; D020030:Nitric Oxide Donors; D010070:Oxalates; D017382:Reactive Oxygen Species; C110881:S-nitro-N-acetylpenicillamine; D009569:Nitric Oxide; C015407:oxalomalic acid; D004050:Ditiocarb; D007521:Isocitrate Dehydrogenase; D002374:Catalase; D013482:Superoxide Dismutase; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D010396:Penicillamine; D000640:Amitrole