title: Dual actions involved in arsenite-induced oxidative DNA damage.
abstract: Arsenic is a recognized human carcinogen, but the mechanism of carcinogenesis is not well understood. Oxidative stress and inhibition of DNA damage repair have been postulated as potential carcinogenic actions of arsenic. The present study tests the hypothesis that arsenite not only induces oxidative stress but also inhibits the activity of the DNA base excision repair protein, poly(ADP-ribose) polymerase-1 (PARP-1), leading to exacerbation of the oxidative DNA damage induced by arsenic. HaCat cells were treated with arsenite for 24 h before measuring 8-hydroxyl-2'-deoxyguanosine (8-OHdG), PARP-1 activity, and reactive oxygen species (ROS). Zinc supplementation and PARP-1 siRNA were used to increase or decrease, respectively, the PARP-1 protein's physiological function. At high concentrations (10 microM or higher), arsenite greatly induced oxidative DNA damage, as indicated by 8-OHdG formation. At lower concentrations (1 microM), arsenite did not produce detectable 8-OHdG, but was still able to effectively inhibit PARP-1 activity. Zinc supplementation reduced the formation of 8-OHdG, restored the PARP-1 activity inhibited by arsenite, but did not decrease ROS production. SiRNA knockdown of PARP-1 did not affect the 8-OHdG level induced by arsenic, while it greatly increased the 8-OHdG level produced by hydrogen peroxide indicating that PARP-1 is a molecular target of arsenite. Our findings demonstrate that in addition to inducing oxidative stress at higher concentrations, arsenite can also inhibit the function of a key DNA repair protein, PARP-1, even at very low concentrations, thus exacerbating the overall oxidative DNA damage produced by arsenite, and potentially, by other oxidants as well.
authors.affiliation: Program of Toxicology, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, USA.
authors.forename: Xu-Jun
authors.initials: XJ
authors.lastname: Qin
authors.forename: Laurie G
authors.initials: LG
authors.lastname: Hudson
authors.forename: Wenlan
authors.initials: W
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Ding
authors.forename: Karen L
authors.initials: KL
authors.lastname: Cooper
authors.forename: Ke Jian
authors.initials: KJ
authors.lastname: Liu
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D018053:Arsenites / Q000494:pharmacology*; D002478:Cells, Cultured; D004249:DNA Damage / Q000187:drug effects*; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000032:analysis / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology
chemical_list: D018053:Arsenites; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D017382:Reactive Oxygen Species; D000080242:8-Hydroxy-2'-Deoxyguanosine; D006861:Hydrogen Peroxide; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D003849:Deoxyguanosine; D015032:Zinc; C015001:arsenite