Li D, Morimoto K, Takeshita T, Lu Y
Department of Preventive Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.
Environ Health Perspect. 2001 May;109(5):523-6. doi: 10.1289/ehp.01109523.
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 microM 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 (H(2)O(2))-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 H(2)O(2), 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 H(2)O(2), 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 H(2)O(2), As-induced DNA damage was repaired more slowly in unstimulated lymphocytes.
为了证实砷（As）在植物血凝素（PHA）刺激和未刺激的人类淋巴细胞中诱导氧化DNA损伤，我们使用碱性彗星试验结合特定酶[甲酰胺嘧啶-DNA糖基化酶（FPG）]消化来测量As诱导的碱基损伤。结果表明，在用10微摩尔As处理细胞2小时后，碱性彗星试验很容易检测到酶敏感位点。在As处理的细胞中观察到的FPG产生的DNA单链断裂（SSB）的修复模式与过氧化氢（H₂O₂）处理的细胞中的修复模式相当。酶产生的SSB，即As诱导的碱基损伤，在PHA刺激的淋巴细胞中更显著。在PHA刺激的淋巴细胞中，经2小时修复孵育后，分别约63%和68%的由As和H₂O₂诱导的SSB得到修复，但在未刺激的细胞中分别约为34%和43%。在PHA刺激的淋巴细胞中，分别约40%和49%的由As和H₂O₂诱导的碱基损伤得到修复，但在未刺激的细胞中分别约为19%和21%。这些结果表明，微摩尔浓度的As在人类淋巴细胞中诱导氧化DNA损伤。受损碱基主要可能是嘌呤或甲酰胺嘧啶。与H₂O₂诱导的损伤一样，As诱导的DNA损伤在未刺激的淋巴细胞中修复得更慢。
