摘要赭曲霉毒素A (ochratoxin A, OTA)是一种污染食品的真菌毒素，对许多动物具有肾毒性，肝毒性，免疫毒性，致畸和致癌作用。本研究以人肝癌细胞HepG2为体外模型，研究OTA引起的细胞损伤及对DNA稳定性的影响。MTT结果显示，OTA能抑制HepG2细胞的生长，存在时间剂量——效应关系。OTA引起细胞上清中酸脱氢酶(LDH)，谷草转氨酶(GOT)和谷丙转氨酶(GPT)活性的升高，诱导细胞内活性氧(ROS)生成，降低超氧化物歧化酶(SOD)活力。彗星实验结果显示OTA引起DNA链断裂，形成拖尾现象。同时，本研究还首次研究了OTA对DNA甲基化的影响。HPLC/MS/MS结果显示，经OTA处理后的细胞，其DNA中5-甲基脱氧胞苷(5mdC)百分数显著低于对照组。这些结果表明OTA会抑制HepG2细胞生长，引起氧化损伤，破坏DNA的稳定性和完整性。本研究表明OTA引起的肝毒性可能与氧化损伤和DNA损伤有关。
Abstract：Ochratoxin A (OTA) is a mycotoxin contaminating food and feedstuffs. OTA causes nephrotoxic and hepatotoxic in experimental animals. In the present study, we investigated the oxidative damage and DNA damage induced by OTA. The results showed that OTA inhibited cell proliferation in a time and dose-independent manner, and increased the release of lactate dehydrogenase (LDH), glutamic-oxalacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT). We had also observed a dose-independent production of reactive oxygen species (ROS) and the decrease of superoxide dismutase (SOD) activity in HepG2 cells. OTA-induced DNA strand break, as detected by comet assay, was demonstrated in all group tested. Our work was the first time to research the effect of OTA on the global DNA methylation. The detection of 5-methyl-deoxycytidine (5mdC) indicated that OTA lowered the level of DNA methylation, but there was no significant difference among the groups. These results show that OTA induces oxidative damage, and disrupts the stability and integrity of DNA, which may be involved in OTA-induced hepatotoxicity.
