title: Hydrogen peroxide insult in cultured mammalian cells: relationships between DNA single-strand breakage, poly(ADP-ribose) metabolism and cell killing.
abstract: We examined the effect of exposure to H2O2 at 37 degrees C on Chinese hamster ovary cell survival, DNA single-strand break (SSB) induction and rejoining, and activation of poly(ADP-ribose) (ADPR) polymerase. The effect of the ADPR polymerase inhibitor 3-aminobenzamide on each of these processes was also determined. SSB induction increased progressively with increasing H2O2 concentration. SSB levels were maximal after approx. 5 min of exposure to H2O2 (100 microM) and then decreased at longer times. This decrease, which paralleled the time-dependent depletion of H2O2, was due to the rejoining of SSBs. 3-Aminobenzamide enhanced the level of SSBs at each time point. H2O2 increased the level of both ADPR synthesis and NAD+ depletion (both measures of ADPR polymerase activity) in a concentration-dependent fashion, with the maximum effect being reached after approx. 20 min. After 100 microM H2O2, the effects on both ADPR and NAD+ were reversible. 3-Aminobenzamide completely blocked the effects of the oxidant on both NAD+ and ADPR levels. Thus, SSB induction by H2O2 at 37 degrees C was accompanied by a marked but reversible stimulation of ADPR polymerase. However, cell killing by H2O2 was only slightly enhanced in the presence of 3-aminobenzamide (5 mM), so the above-mentioned effects do not appear to be relevant to the cytotoxic effect of H2O2 under these conditions. Comparing these results with data obtained previously for cells treated with H2O2 at 4 degrees C suggests that the mechanisms of DNA strand breakage and cell killing may be quite different at the two temperatures, and that DNA damage at 37 degrees C may be indirectly mediated by temperature-dependent metabolic events.
authors.affiliation: Istituto di Farmacologia e Farmacognosia, Universita di Urbino, Italy.
authors.forename: O
authors.initials: O
authors.lastname: Cantoni
authors.forename: F
authors.initials: F
authors.lastname: Cattabeni
authors.forename: V
authors.initials: V
authors.lastname: Stocchi
authors.forename: R E
authors.initials: RE
authors.lastname: Meyn
authors.forename: P
authors.initials: P
authors.lastname: Cerutti
authors.forename: D
authors.initials: D
authors.lastname: Murray
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D004247:DNA / Q000187:drug effects*; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D006861:Hydrogen Peroxide / Q000633:toxicity*; D009243:NAD / Q000378:metabolism; D009702:Nucleoside Diphosphate Sugars / Q000378:metabolism*; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D013997:Time Factors
chemical_list: D001549:Benzamides; D009702:Nucleoside Diphosphate Sugars; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D009243:NAD; D011064:Poly Adenosine Diphosphate Ribose; C025160:3-aminobenzamide; D004247:DNA; D006861:Hydrogen Peroxide; D011065:Poly(ADP-ribose) Polymerases