Department of Toxicogenetics, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
Mutat Res. 2011 May 10;709-710:49-59. doi: 10.1016/j.mrfmmm.2011.02.013. Epub 2011 Mar 4.
Various in vitro test systems have been developed for genotoxic risk assessment in early drug development. However, these genotoxicity tests often show limited specificity, and provide limited insights into the mode of toxicity of the tested compounds. To identify genes that could serve as specific biomarkers for genotoxicity or oxidative stress, we exposed mouse embryonic stem (ES) cells to various genotoxic and oxidative stress-inducing compounds and performed genome-wide expression profiling. Differentially expressed genes were classified based on the fold-change of expression and their specificity for either genotoxic or oxidative stress. Promoter regions of four selected genes (Ephx1, Btg2, Cbr3 and Perp) were fused to a DsRed fluorescent reporter gene and stably integrated in mouse ES cells. Established stable reporter cell lines displayed significant induction of DsRed expression upon exposure to different classes of genotoxic and oxidative stress-inducing compounds. In contrast, exposure to non-genotoxic carcinogenic compounds did not induce DsRed expression even at cytotoxic doses. Expression of the Cbr3-DsRed reporter was more responsive to compounds that induce oxidative stress while the other three DsRed reporters reacted more specific to direct-acting genotoxic agents. Therefore, the differential response of the Btg2- and Cbr3-DsRed reporters can serve as indicator for the main action mechanism of genotoxic and oxidative stress-inducing compounds. In addition, we provide evidence that inhibition of DNA replication results in preferential activation of the Btg2-DsRed genotoxicity reporter. In conclusion, we have generated sensitive mouse ES cell reporter systems that allow detection of genotoxic and oxidative stress-inducing properties of chemical compounds and can be used in high-throughput assays.
各种体外测试系统已被开发用于早期药物开发中的遗传毒性风险评估。然而,这些遗传毒性测试通常显示出有限的特异性,并且对所测试化合物的毒性模式提供的见解有限。为了鉴定可作为遗传毒性或氧化应激特异性生物标志物的基因,我们将小鼠胚胎干细胞 (ES) 暴露于各种遗传毒性和氧化应激诱导化合物,并进行全基因组表达谱分析。差异表达基因根据表达的倍数变化及其对遗传毒性或氧化应激的特异性进行分类。选择的四个基因 (Ephx1、Btg2、Cbr3 和 Perp) 的启动子区域与 DsRed 荧光报告基因融合,并稳定整合到小鼠 ES 细胞中。建立的稳定报告细胞系在暴露于不同类别的遗传毒性和氧化应激诱导化合物时显示出 DsRed 表达的显著诱导。相比之下,即使在细胞毒性剂量下,非遗传毒性致癌化合物的暴露也不会诱导 DsRed 表达。Cbr3-DsRed 报告基因的表达对诱导氧化应激的化合物更为敏感,而其他三个 DsRed 报告基因对直接作用的遗传毒性剂反应更为特异。因此,Btg2-和 Cbr3-DsRed 报告基因的差异反应可作为遗传毒性和氧化应激诱导化合物主要作用机制的指标。此外,我们提供了证据表明,抑制 DNA 复制会导致 Btg2-DsRed 遗传毒性报告基因的优先激活。总之,我们生成了敏感的小鼠 ES 细胞报告系统,可用于检测化学化合物的遗传毒性和氧化应激诱导特性,并可用于高通量测定。
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