Endonuclease III, Formamidopyrimidine-DNA Glycosylase, and Proteinase K Additively Enhance Arsenic-Induced DNA Strand Breaks in Human Cells

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• 作者：Tsu-Shing Wang ; Chiao-Hui Chung ; Alexander S. S. Wang ; Da-Tian Bau ; Thangavel Samikkannu ; Kun-Yan Jan ; Yang-Ming Cheng ; and Te-Chang Lee
• 刊名：Chemical Research in Toxicology
• 出版年：2002
• 出版时间：October 2002
• 年：2002
• 卷：15
• 期：10
• 页码：1254 - 1258
• 全文大小：89K
• 年卷期：v.15,no.10(October 2002)
• ISSN：1520-5010

文摘

We report here that sequential digestion with endonuclease III, formamidopyrimidine-DNAglycosylase, and proteinase K in Tris buffer markedly increased the sensitivity for detectingDNA damage in arsenic-treated cells. These three enzymes increased DNA strand breaks inan additive manner. By using this sequential-enzyme-digestion comet assay, we demonstratedthat trivalent inorganic arsenic induced more DNA damage than monomethylarsonous acid,monomethylarsonic acid, and dimethylarsinic acid in human blood cell lines. However, trivalentinorganic arsenic was far less potent than monomethylarsonous acid in inhibiting pyruvatedehydrogenase activity. Therefore, different mechanisms are involved in inhibiting pyruvatedehydrogenase activity and inducing DNA damage. Our results also indicate while trivalentinorganic arsenic induced more endonuclease III-digestible adducts, monomethylarsonous acidand monomethylarsonic acid induced more proteinase K-digestible adducts. These resultssuggest there is a difference in the mechanism for inducing DNA damage between inorganicand organic methylated arsenic compounds.