title: Endonuclease III, formamidopyrimidine-DNA glycosylase, and proteinase K additively enhance arsenic-induced DNA strand breaks in human cells.
abstract: We report here that sequential digestion with endonuclease III, formamidopyrimidine-DNA glycosylase, and proteinase K in Tris buffer markedly increased the sensitivity for detecting DNA damage in arsenic-treated cells. These three enzymes increased DNA strand breaks in an additive manner. By using this sequential-enzyme-digestion comet assay, we demonstrated that trivalent inorganic arsenic induced more DNA damage than monomethylarsonous acid, monomethylarsonic acid, and dimethylarsinic acid in human blood cell lines. However, trivalent inorganic arsenic was far less potent than monomethylarsonous acid in inhibiting pyruvate dehydrogenase activity. Therefore, different mechanisms are involved in inhibiting pyruvate dehydrogenase activity and inducing DNA damage. Our results also indicate while trivalent inorganic arsenic induced more endonuclease III-digestible adducts, monomethylarsonous acid and monomethylarsonic acid induced more proteinase K-digestible adducts. These results suggest there is a difference in the mechanism for inducing DNA damage between inorganic and organic methylated arsenic compounds.
authors.affiliation: Department of Life Sciences, Chung Shan Medical University, Taichung, 402, Taiwan, ROC.
authors.forename: Tsu-Shing
authors.initials: TS
authors.lastname: Wang
authors.forename: Chiao-Hui
authors.initials: CH
authors.lastname: Chung
authors.forename: Alexander S S
authors.initials: AS
authors.lastname: Wang
authors.forename: Da-Tian
authors.initials: DT
authors.lastname: Bau
authors.forename: Thangavel
authors.initials: T
authors.lastname: Samikkannu
authors.forename: Kun-Yan
authors.initials: KY
authors.lastname: Jan
authors.forename: Yang-Ming
authors.initials: YM
authors.lastname: Cheng
authors.forename: Te-Chang
authors.initials: TC
authors.lastname: Lee
mesh_terms: D001151:Arsenic / Q000009:adverse effects* / Q000378:metabolism; D018736:DNA Adducts / Q000032:analysis*; D004249:DNA Damage; D043382:DNA-Formamidopyrimidine Glycosylase; D043224:Deoxyribonuclease (Pyrimidine Dimer); D004706:Endodeoxyribonucleases / Q000494:pharmacology*; D019286:Endopeptidase K / Q000494:pharmacology*; D029968:Escherichia coli Proteins; D018922:HL-60 Cells; D006801:Humans; D009699:N-Glycosyl Hydrolases / Q000494:pharmacology*; D012680:Sensitivity and Specificity
chemical_list: D018736:DNA Adducts; D029968:Escherichia coli Proteins; D004706:Endodeoxyribonucleases; D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; D019286:Endopeptidase K; D001151:Arsenic