Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung 404, Taiwan; Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan.
Environ Toxicol. 2013 Oct;28(10):579-87. doi: 10.1002/tox.20752. Epub 2011 Sep 2.
Our earlier studies have demonstrated that gallic acid (GA) induced cytotoxic effects including induction of apoptosis and DNA damage and inhibited the cell migration and invasion in human cancer cells. However, GA-affected DNA damage and repair gene expressions in human prostate cancer cells are still unclear. In this study, we investigated whether or not GA induces DNA damage and inhibits DNA repair gene expression in a human prostate cancer cell line (PC-3). The results from flow cytometric assay indicated that GA decreased the percentage of viable PC-3 cells in a dose- and time-dependent manner. PC-3 cells after exposure to different doses (50, 100, and 200 μM) of GA and various periods of time (12, 24, and 48 h) led to a longer DNA migration smear (comet tail) occurred based on the single cell gel electrophoresis (comet assay). These observations indicated that GA-induced DNA damage in PC-3 cells, which also confirmed by 4,6-diamidino-2-phenylindole dihydrochloride staining and DNA agarose gel electrophoresis. Alternatively, results from real-time polymerase chain reaction assay also indicated that GA inhibited ataxia telangiectasia mutated, ataxia-telangiectasia and Rad3-related, O⁶-methylguanine-DNA methyltransferase, DNA-dependent serine/threonine protein kinase, and p53 mRNA expressions in PC-3 cells. Taken together, the present study showed that GA caused DNA damage and inhibited DNA repair genes as well as both effects may be the critical factors for GA-inhibited growth of PC-3 cells in vitro.
我们之前的研究表明，没食子酸（GA）诱导细胞毒性作用，包括诱导细胞凋亡和 DNA 损伤，并抑制人癌细胞的迁移和侵袭。然而，GA 对人前列腺癌细胞中 DNA 损伤和修复基因表达的影响尚不清楚。在这项研究中，我们研究了 GA 是否会在人前列腺癌细胞系（PC-3）中诱导 DNA 损伤并抑制 DNA 修复基因的表达。流式细胞术分析的结果表明，GA 以剂量和时间依赖的方式降低了活细胞的百分比。PC-3 细胞暴露于不同剂量（50、100 和 200 μM）GA 和不同时间（12、24 和 48 h）后，基于单细胞凝胶电泳（彗星试验），出现更长的 DNA 迁移拖尾（彗星尾）。这些观察结果表明，GA 诱导了 PC-3 细胞中的 DNA 损伤，这也通过 4,6-二脒基-2-苯基吲哚二盐酸盐染色和 DNA 琼脂糖凝胶电泳得到了证实。另外，实时聚合酶链反应分析的结果还表明，GA 抑制了 PC-3 细胞中的 ATM、ATR 和 Rad3 相关蛋白、O⁶-甲基鸟嘌呤-DNA 甲基转移酶、DNA 依赖性丝氨酸/苏氨酸蛋白激酶和 p53 mRNA 的表达。综上所述，本研究表明 GA 导致 DNA 损伤并抑制 DNA 修复基因，这两种作用可能是 GA 抑制 PC-3 细胞体外生长的关键因素。
