Wang Lu, Mao Boyu, He Huixin, Shang Yu, Zhong Yufang, Yu Zhiqiang, Yang Yiting, Li Hui, An Jing
School of Environmental and Chemical Engineering , Shanghai University , Shanghai 200444 , China . Email:
Implant Dentistry Department , Jiangbei Dental Hospital , Ningbo 315000 , China.
Toxicol Res (Camb). 2018 Oct 12;8(1):38-45. doi: 10.1039/c8tx00199e. eCollection 2019 Jan 1.
Triclosan (TCS) is used as an antimicrobial agent and has been widely dispersed and detected in the environment and organisms including human samples. Methyl-triclosan (MTCS) is the predominant bacterial TCS metabolite. At present, the toxicological effects and mechanism of TCS and MTCS are still not fully understood. In this study, the cytotoxic effects of TCS and MTCS in HepG2 cells were investigated in terms of cell proliferation, comet assay, cell cycle, and apoptosis. In addition, the expressions of related proteins were detected with western blotting analysis. The results showed that TCS could significantly inhibit cell proliferation, while MTCS had no obvious effect on cell growth. Both TCS and MTCS caused oxidative injury associated with HO-1 induction and increased DNA strand breaks, which consequently initiated the damage repair process up-regulation of DNA-PKcs. In addition, TCS blocked the HepG2 cells in S and G2/M phases of cell cycle through down-regulation of cyclin A2 and CDK; while MTCS induced cell cycle arrest at the S phase through up-regulation of cyclin A2 and CDK. Furthermore, TCS activated p53 mediated apoptosis in HepG2 cells in a caspase-independent manner, while MTCS induced apoptosis was dependent on caspase. Moreover, TCS exposure exhibited more severe toxicity in HepG2 cells as compared with MTCS exposure, indicating that the replacement of the ionizable proton in TCS by the methyl group in MTCS is correlated with the cellular toxicity and the molecular mechanism.
三氯生（TCS）用作抗菌剂，已在包括人体样本在内的环境和生物体中广泛扩散并被检测到。甲基三氯生（MTCS）是细菌中主要的三氯生代谢产物。目前，三氯生和甲基三氯生的毒理学效应及作用机制仍未完全明确。本研究从细胞增殖、彗星试验、细胞周期和凋亡等方面，对三氯生和甲基三氯生在肝癌细胞系HepG2中的细胞毒性作用进行了研究。此外，通过蛋白质免疫印迹分析检测相关蛋白的表达。结果表明，三氯生可显著抑制细胞增殖，而甲基三氯生对细胞生长无明显影响。三氯生和甲基三氯生均会引发与血红素加氧酶-1诱导相关的氧化损伤，并增加DNA链断裂，进而启动损伤修复过程——DNA依赖蛋白激酶催化亚基（DNA-PKcs）上调。此外，三氯生通过下调细胞周期蛋白A2和周期蛋白依赖性激酶（CDK），使HepG2细胞阻滞于细胞周期的S期和G2/M期；而甲基三氯生则通过上调细胞周期蛋白A2和CDK，诱导细胞周期阻滞于S期。此外，三氯生以不依赖半胱天冬酶的方式激活p53介导的HepG2细胞凋亡，而甲基三氯生诱导的凋亡则依赖于半胱天冬酶。而且，与甲基三氯生暴露相比，三氯生暴露在HepG2细胞中表现出更严重的毒性，表明甲基三氯生中甲基取代三氯生中可电离质子与细胞毒性及分子机制相关。
