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.
Chazotte-Aubert
L
L
Unit of Endogenous Cancer Risk Factors, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon Cedex 08, France.
Oikawa
S
S
Gilibert
I
I
Bianchini
F
F
Kawanishi
S
S
Ohshima
H
H
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