Endogenous and exogenous nitric oxide enhance the DNA strand scission induced by tert-butylhydroperoxide in PC12 cells via peroxynitrite-dependent and independent mechanisms, respectively.
A short-term exposure to tert-butylhydroperoxide (tB-OOH) promoted a concentration-dependent formation of DNA single-strand breaks in PC12 cells. These events were paralleled by an increase in the cytosolic concentration of Ca2+ that was in part cleared by the mitochondria. Unlike the extent of Ca2+ mobilization and/or mitochondrial Ca2+ clearance, the DNA strand scission evoked by the hydroperoxide was markedly reduced by the nitric oxide (NO) scavenger 2-phenyl-4,4,5,5-tetramethylimidazolin-1-oxyl-3-oxide (PTIO) or by the NO synthase inhibitor N-nitro-L-arginine methylester (L-NAME). Inhibitors of electron transport (rotenone and myxothiazol), ruthenium red (RR, a polycation which inhibits the calcium uniporter of mitochondria), or peroxynitrite scavengers (Trolox and L-methionine) were as effective as PTIO or L-NAME in inhibiting the DNA-damaging response mediated by tB-OOH. Rotenone, RR or peroxynitrite scavengers did not further reduce the residual DNA cleavage observed following treatment with tB-OOH in L-NAME-supplemented cells. Exogenous NO also increased the DNA damage caused by tB-OOH in L-NAME-supplemented cells and this response was blunted by RR or by inhibitors of electron transport but was insensitive to peroxynitrite scavengers. We conclude that both endogenous and exogenous NO enhance the DNA cleavage generated by tB-OOH in PC12 cells. However, only endogenous NO set the bases for an involvement of peroxynitrite in this DNA-damaging response.
Sestili
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Istituto di Farmacologia e Farmacognosia and Centro di Farmacologia Oncologica Sperimentale, Università di Urbino, Via S. Chiara, 27, 61029, Urbino (PU), Italy.
Clementi
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E
Guidarelli
A
A
Sciorati
C
C
Cantoni
O
O
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002839:Chromans / Q000494:pharmacology; D003497:Cyclic N-Oxides / Q000494:pharmacology*; D004249:DNA Damage / Q000187:drug effects / Q000502:physiology*; D004277:DNA, Single-Stranded / Q000187:drug effects; D004579:Electron Transport / Q000187:drug effects; D016166:Free Radical Scavengers / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology*; D008689:Methacrylates; D008715:Methionine / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009566:Nitrates / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D016877:Oxidants; D016716:PC12 Cells; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D012402:Rotenone / Q000494:pharmacology; D012430:Ruthenium Red / Q000494:pharmacology; D026423:S-Nitroso-N-Acetylpenicillamine; D013844:Thiazoles / Q000494:pharmacology; D020122:tert-Butylhydroperoxide / Q000494:pharmacology*
D002839:Chromans; D003497:Cyclic N-Oxides; D004277:DNA, Single-Stranded; D016166:Free Radical Scavengers; D007093:Imidazoles; D008689:Methacrylates; D009566:Nitrates; D020030:Nitric Oxide Donors; D016877:Oxidants; D013844:Thiazoles; D012402:Rotenone; D012430:Ruthenium Red; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; C039642:peroxynitric acid; D009569:Nitric Oxide; C030517:myxothiazol; D026423:S-Nitroso-N-Acetylpenicillamine; D020122:tert-Butylhydroperoxide; D008715:Methionine; D010396:Penicillamine; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester