| Formamidopyrimidine-DNA Glycosylase Enhances Arsenic-Induced DNA Strand Breaks in PHA-Stimulated and Unstimulated Human Lymphocytes Dasheng Li, Kanehisa Morimoto, Tatsuya Takeshita, and Yuquan Lu Department of Preventive Medicine, Osaka University Graduate School of Medicine, Osaka, Japan Abstract
To confirm that arsenic (As) induces oxidative DNA damage in phytohemagglutinin (PHA) -stimulated and unstimulated human lymphocytes, we used the alkaline comet assay combined with specific enzyme [formamidopyrimidine-DNA glycosylase (FPG) ] digestion to measure As-induced base damage. The results showed that the enzyme-sensitive sites were readily detected with the alkaline comet assay after the cells were treated with 10 µM As for 2 hr. The repair patterns observed for FPG-created DNA single strand breaks (SSBs) in As-treated cells were comparable to those in hydrogen peroxide (H2O2) -treated cells. The enzyme-created SSBs, As-induced base damage, were more significant in PHA-stimulated lymphocytes. About 63% and 68% of SSBs induced by As and H2O2, respectively, were repaired in PHA-stimulated lymphocytes by 2-hr repair incubation, but about 34% and 43%, respectively, were repaired in unstimulated cells. About 40% and 49% of base damage induced by As and H2O2, respectively, were repaired in PHA-stimulated lymphocytes, but about 19% and 21%, respectively, were repaired in unstimulated cells. These results indicated that As induced oxidative DNA damage in human lymphocytes at micromolar concentrations. The damaged bases could be chiefly purines or formamidopyrimidines. Like the damage induced by H2O2, As-induced DNA damage was repaired more slowly in unstimulated lymphocytes. Key words: arsenic, comet assay, formamidopyrimidine-DNA glycosylase (FPG) , human lymphocytes, oxidative DNA damage. Environ Health Perspect 109:523-526(2001) . [Online Online 11 May 2001] http://ehpnet1.niehs.nih.gov/docs/2001/109p523-526li/ abstract.html Address correspondence to K. Morimoto, Department of Social and Environmental Medicine, Osaka University Graduate School of Medicine F1, 2-2 Yamada-oka, Suita, Osaka 565-6879, Japan. Telephone: +81(06) 6879-3920. Fax: +81(06) 6879-3929. E-mail: morimoto@envi.med.osaka-u.ac.jp D. Li is a visiting researcher from the Health and Antiepidemic Station of Guizhou Province, 40# Ba Ge Yan Road, Guiyang 550004, China. This study was supported in part from China Scholarship Council (CSC) , no. 98952010. Received 13 October 2000 ; accepted 6 December 2000.
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