Endonuclease III, formamidopyrimidine-DNA glycosylase, and proteinase K additively enhance arsenic-induced DNA strand breaks in human cells.
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.
Wang
Tsu-Shing
TS
Department of Life Sciences, Chung Shan Medical University, Taichung, 402, Taiwan, ROC.
Chung
Chiao-Hui
CH
Wang
Alexander S S
AS
Bau
Da-Tian
DT
Samikkannu
Thangavel
T
Jan
Kun-Yan
KY
Cheng
Yang-Ming
YM
Lee
Te-Chang
TC
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
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