Downregulation of Rad51 participates in OTA-induced DNA double-strand breaks in GES-1 cells in vitro
Downregulation of Rad51 participates in OTA-induced DNA double-strand breaks in GES-1 cells in vitro
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Rad51 的下调参与体外 GES-1 细胞中 OTA 诱导的 DNA 双链断裂。
DOI：
10.1016/j.toxlet.2014.02.002
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发表时间：
2014-04-21
影响因子：
3.5
通讯作者：
Zhang, Xianghong
中科院分区：
文献类型：
--
作者：
Lian, Hongguang;Cui, Jinfeng;Zhang, Xianghong
赭曲霉毒素A（Ochratoxin A，OTA）是一种广泛存在的真菌毒素，具有致癌、致畸和肾毒性作用，可导致人胃上皮永生化细胞（GES-1）G2期阻滞。DSB可引起基因组不稳定性、突变和肿瘤转化，DSB的不适当修复可导致癌症的发展。Rad 51是DSB修复同源重组（HR）途径中的关键蛋白。Rad 51在DNA损伤修复中的作用因细胞毒性药物的不同而不同。OTA对GES-1细胞中Rad 51表达的影响及其在OTA诱导的DSB中的作用尚不清楚。本研究的目的是阐明Rad 51在OTA诱导的GES-1细胞DSB中的作用。结果表明，OTA处理可降低细胞内Rad 51的表达，并呈剂量和时间依赖性。通过siRNA特异性下调Rad 51诱导DSB和G2期阻滞。用表达Rad 51的质粒转染过表达Rad 51的细胞，可部分挽救OTA处理的细胞中的DSB和G2期阻滞。研究结果表明，下调Rad 51有助于OTA诱导的GES-1细胞DNA损伤。用siRNA敲低p53 for 48可有效逆转GES-1细胞中Rad 51的下调，并减少OTA诱导的DSB。此外，特异性ERK抑制剂PD 98059或特异性p38 MAPK抑制剂SB 203580预处理可显著减弱OTA对GES-1细胞Rad 51的下调作用。因此，上述结果表明，Rad 51的下调参与了OTA在体外诱导的GES 1细胞DNA双链断裂。p53、ERK和p38信号通路均参与了这一过程。(C)2014爱思唯尔爱尔兰有限公司版权所有。
Ochratoxin A (OTA), a mycotoxin produced by ubiquitous Aspergilli, is carcinogenic, teratogenic, andnephrotoxic strand breaks (DSBs) and resulted in G2 phase arrest in human gastric epithelium immortalized (GES-1) cells. DSBs can cause genomic instability, mutations, and neoplastic transformations, and improper repairof DSBs may lead to the development of cancer. Rad51 is a key protein in the homologous recombination(HR) pathway of DSBs repair. The roles of Rad51 in the repair of DNA damage vary in response to differenttypes of cytotoxic agents. The effect of OTA on Rad51 expression and its putative role in the OTA-inducedDSBs in GES-1 cells are still not clear enough. The aim of the current study is to elucidate the role ofRad51 in OTA-induced DSBs in GES-1 cells. The results showed that OTA treatment decreased Rad51expression in a dose-and time-dependent manner. Specific downregulation of Rad51 by siRNA inducedDSBs and G2 phase arrest. Rad51 overexpression by transfection with a Rad51-expressing plasmid partlyrescued the DSBs and G2 phase arrest in OTA-treated cells. The findings indicate that downregulation ofRad51 contributes to OTA-induced DNA damage in GES-1 cells. Knockdown of p53 with siRNA for 48 heffectively reversed the downregulation of Rad51, and decreased the OTA-induced DSBs in GES-1 cells. In addition, the downregulation of Rad51 induced by OTA could be significantly attenuated with specificERK inhibitor PD98059 or specific p38 MAPK inhibitor SB203580 pre-treatment in GES-1 cells. Thus, theresults suggest that downregulation of Rad51 participates in OTA-induced DNA double-strand breaks inGES1 cells in vitro. And p53, ERK and p38 signaling pathways are all involved in the process. (C) 2014 Elsevier Ireland Ltd. All rights reserved.