Effect of Chemical Mutagens and Carcinogens on Gene Expression Profiles in Human TK6 Cells

Characterization of toxicogenomic signatures of carcinogen exposure holds significant promise for mechanistic and predictive toxicology. In vitro transcriptomic studies allow the comparison of the response to chemicals with diverse mode of actions under controlled experimental conditions. We conducted an in vitro study in TK6 cells to characterize gene expression signatures of exposure to 15 genotoxic carcinogens frequently used in European industries. We also examined the dose-responsive changes in gene expression, and perturbation of biochemical pathways in response to these carcinogens. TK6 cells were exposed at 3 dose levels for 24 h with and without S9 human metabolic mix. Since S9 had an impact on gene expression (885 genes), we analyzed the gene expression data from cells cultures incubated with S9 and without S9 independently. The ribosome pathway was affected by all chemical-dose combinations. However in general, no similar gene expression was observed among carcinogens. Further, pathways, i.e. cell cycle, DNA repair mechanisms, RNA degradation, that were common within sets of chemical-dose combination were suggested by clustergram. Linear trends in dose–response of gene expression were observed for Trichloroethylene, Benz[a]anthracene, Epichlorohydrin, Benzene, and Hydroquinone. The significantly altered genes were involved in the regulation of (anti-) apoptosis, maintenance of cell survival, tumor necrosis factor-related pathways and immune response, in agreement with several other studies. Similarly in S9+ cultures, Benz[a]pyrene, Styrene and Trichloroethylene each modified over 1000 genes at high concentrations. Our findings expand our understanding of the transcriptomic response to genotoxic carcinogens, revealing the alteration of diverse sets of genes and pathways involved in cellular homeostasis and cell cycle control.致癌物暴露的毒基因组特征表征，在机制毒理学与预测毒理学领域具有重要应用前景。体外转录组学研究可在受控实验条件下，比较不同作用模式化学品所引发的细胞响应。本研究以TK6细胞为模型开展体外实验，对欧洲工业中常用的15种遗传毒性致癌物暴露后的基因表达特征进行表征；同时还分析了这些致癌物暴露下基因表达的剂量依赖性变化，以及生化通路的扰动情况。将TK6细胞分别置于添加与不添加S9人源代谢混合液的培养基中，以3种剂量水平暴露24小时。由于S9代谢混合液会对基因表达产生影响（共涉及885个基因），因此我们分别对添加S9与不添加S9的细胞培养样本的基因表达数据进行了独立分析。核糖体通路在所有化学物-剂量组合处理后均出现异常调控，但总体而言，不同致癌物之间并未观察到相似的基因表达谱。此外，聚类热图分析显示，细胞周期、DNA修复机制、RNA降解等通路在特定化学物-剂量组合组中存在共同扰动。三氯乙烯、苯并[a]蒽、环氧氯丙烷、苯以及对苯二酚的基因表达剂量响应呈现线性趋势。显著差异表达基因参与（抗）凋亡调控、细胞存活维持、肿瘤坏死因子相关通路以及免疫应答过程，这与其他多项研究结果一致。同样，在添加S9的培养体系中，高浓度下的苯并[a]芘、苯乙烯与三氯乙烯均可调控超过1000个基因的表达。本研究结果加深了我们对遗传毒性致癌物转录组响应的认知，揭示了参与细胞稳态与细胞周期调控的多组基因与通路的异常变化。