title: Different effects of tert-butylhydroperoxide-induced peroxynitrite-dependent and -independent DNA single-strand breakage on PC12 cell poly(ADP-ribose) polymerase activity.
abstract: The short-chain lipid hydroperoxide analogue tert-butylhydroperoxide induces peroxynitrite-dependent and -independent DNA single strand breakage in PC12 cells. U937 cells that do not express constitutive nitric oxide synthase respond to tert-butylhydroperoxide treatment with peroxynitrite-independent DNA cleavage. Under experimental conditions leading to equivalent strand break frequencies, the analysis of poly(ADP-ribose) polymerase activity showed an increase in PC12 cells but not in U937 cells. The enhanced poly(ADP-ribose) polymerase activity observed in PC12 cells was paralleled by a significant decline in NAD+ content and both events were prevented by treatments suppressing formation of peroxynitrite. Although DNA breaks were rejoined at similar rates in the two cell lines, an inhibitor of poly(ADP-ribose) polymerase delayed DNA repair in PC12 cells but had hardly any effect in U937 cells. The results obtained using the latter cell type were confirmed with an additional cell line (Chinese hamster ovary cells) that does not express nitric oxide synthase. Collectively, our data suggest that tert-butylhydroperoxide-induced peroxynitrite-independent DNA strand scission is far less effective than the DNA cleavage generated by endogenous peroxynitrite in stimulating the activity of poly(ADP-ribose) polymerase.
authors.affiliation: Istituto di Farmacologia e Farmacognosia, Università di Urbino, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Palomba
authors.forename: A
authors.initials: A
authors.lastname: Guidarelli
authors.forename: A I
authors.initials: AI
authors.lastname: Scovassi
authors.forename: O
authors.initials: O
authors.lastname: Cantoni
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D016466:CHO Cells; D002417:Cattle; D006224:Cricetinae; D004249:DNA Damage / Q000187:drug effects*; D004260:DNA Repair / Q000187:drug effects; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D009243:NAD / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D016716:PC12 Cells; D030421:Peroxynitrous Acid / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D051381:Rats; D013997:Time Factors; D020298:U937 Cells; D020122:tert-Butylhydroperoxide / Q000494:pharmacology*
chemical_list: D001549:Benzamides; D004277:DNA, Single-Stranded; D009243:NAD; D030421:Peroxynitrous Acid; C025160:3-aminobenzamide; D020122:tert-Butylhydroperoxide; D011065:Poly(ADP-ribose) Polymerases; D019331:NG-Nitroarginine Methyl Ester