title: Quinone thioether-mediated DNA damage, growth arrest, and gadd153 expression in renal proximal tubular epithelial cells.
abstract: Although the conjugation of quinones with glutathione is associated with the process of detoxication, the reaction frequently facilitates quinone-induced toxicity. Thiol conjugates of quinones retain the ability to redox cycle and generate reactive oxygen species (ROS), contributing to the biological (re)activity of a variety of polyphenolic compounds. 2-Bromo-bis(glutathion-S-yl) hydroquinone (2-Br-bis(GSyl)HQ) and 2-bromo-6-(glutathion-S-yl) hydroquinone [2-Br-6-(GSyl)HQ] are potent nephrotoxicants in rats, inducing rapid karyolysis in vivo and DNA single-strand breaks in cultured renal proximal tubular epithelial cells (LLC-PK1). We investigated the cellular and molecular responses initiated after exposure of LLC-PK1 cells to 2-Br-bis(GSyl)HQ and 2-Br-6-(GSyl)HQ. Both quinone thioethers cause the concentration-dependent formation of DNA single-strand breaks, rapidly (2-10 min) inhibit DNA synthesis, and increase the expression of gadd153, a gene responsive to growth arrest and DNA damage. The addition of catalase to LLC-PK1 cells exposed to 2-Br-6-(GSyl)HQ or 2-Br-bis(GSyl)HQ effectively prevents gadd153 induction, which is consistent with findings that the gadd153 gene is subject to redox modulation and that ROS play an important role in quinone thioether-mediated cytotoxicity. Deferoxamine pretreatment also diminishes gadd153 induction, suggesting that in renal proximal tubular epithelial cells, decreased expression of gadd153 is not dependent on the removal of hydrogen peroxide per se but rather on preventing the generation of hydroxyl radical. Chelation of intracellular calcium with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid-acetoxy-methyl ester also reduces gadd153 induction by 2-Br-6-(GSyl)HQ and 2-Br-bis(GSyl)HQ, suggesting a role for calcium in the signaling process. Thus, 2-Br-6-(GSyl)HQ and 2-Br-bis(GSyl)HQ activate a genomic stress response via a signaling pathway that may include ROS, Ca2+, and DNA damage.
authors.affiliation: Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin 78712, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Jeong
authors.forename: J L
authors.initials: JL
authors.lastname: Stevens
authors.forename: S S
authors.initials: SS
authors.lastname: Lau
authors.forename: T J
authors.initials: TJ
authors.lastname: Monks
mesh_terms: D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins; D002374:Catalase / Q000494:pharmacology; D002455:Cell Division; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000187:drug effects; D004249:DNA Damage; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D003609:Dactinomycin / Q000494:pharmacology; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005978:Glutathione / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000633:toxicity; D006873:Hydroquinones / Q000138:chemical synthesis / Q000633:toxicity*; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007700:Kinetics; D014176:Protein Biosynthesis / Q000187:drug effects; D011809:Quinones / Q000138:chemical synthesis / Q000633:toxicity*; D051381:Rats; D013440:Sulfides / Q000138:chemical synthesis / Q000633:toxicity*; D013552:Swine; D013556:Swine, Miniature; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000096:biosynthesis*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D015342:DNA Probes; D004268:DNA-Binding Proteins; C497251:Ddit3 protein, rat; D006873:Hydroquinones; D011809:Quinones; D013440:Sulfides; D014157:Transcription Factors; C101515:2-bromo-6-(glutathion-S-yl)hydroquinone; D051742:Transcription Factor CHOP; D003609:Dactinomycin; D004247:DNA; D003513:Cycloheximide; D002374:Catalase; D005978:Glutathione