Cytotoxicity and site-specific DNA damage induced by nitroxyl anion (NO(-)) in the presence of hydrogen peroxide. Implications for various pathophysiological conditions.
Nitroxyl anion (NO(-)), the one-electron reduction product of nitric oxide (NO(.)), is formed under various physiological conditions. We have used four different assays (DNA strand breakage, 8-oxo-deoxyguanosine formation in calf thymus DNA, malondialdehyde generation from 2'-deoxyribose, and analysis of site-specific DNA damage using (32)P-5'-end-labeled DNA fragments of the human p53 tumor suppressor gene and the c-Ha-ras-1 protooncogene) to study the effects of NO(-) generated from Angeli's salt on DNA damage. It was found that strong oxidants are generated from NO(-), especially in the presence of H(2)O(2) plus Fe(III)-EDTA or Cu(II). NO(.) released from diethylamine-NONOate had no such effect. Distinct effects of hydroxyl radical (HO(.)) scavengers and patterns of site-specific DNA cleavage caused by Angeli's salt alone or by Angeli's salt, H(2)O(2) plus metal ion suggest that NO(-) acts as a reductant to catalyze the formation of the HO(.) from H(2)O(2) plus Fe(III) and formation of Cu(I)-peroxide complexes with a reactivity similar to HO(.) from H(2)O(2) and Cu(II). Angeli's salt and H(2)O(2) exerted synergistically cytotoxic effects to MCF-7 cells, determined by lactate dehydrogenase release assay. Thus NO(-) may play an important role in the etiology of various pathophysiological conditions such as inflammation and neurodegenerative diseases, especially when H(2)O(2) and transition metallic ions are present.
Unit of Endogenous Cancer Risk Factors, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon Cedex 08, France.
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L
Chazotte-Aubert
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S
Oikawa
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I
Gilibert
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F
Bianchini
S
S
Kawanishi
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Ohshima
D000975:Antioxidants / Q000633:toxicity*; D001681:Biological Assay; D004249:DNA Damage / Q000187:drug effects*; D004269:DNA, Bacterial / Q000187:drug effects; D004347:Drug Interactions; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D009589:Nitrogen Oxides / Q000633:toxicity*; D016877:Oxidants / Q000633:toxicity*
D000975:Antioxidants; D004269:DNA, Bacterial; D009589:Nitrogen Oxides; D016877:Oxidants; D006861:Hydrogen Peroxide; C039900:nitroxyl