Ross Jeffrey A, George Barbara Jane, Bruno Maribel, Ge Yue
National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711.
Comput Toxicol. 2017 May;2:39-44. doi: 10.1016/j.comtox.2017.03.001.
Toxicity pathways have been defined as normal cellular pathways that, when sufficiently perturbed as a consequence of chemical exposure, lead to an adverse outcome. If an exposure alters one or more normal biological pathways to an extent that leads to an adverse toxicity outcome, a significant correlation must exist between the exposure, the extent of pathway alteration, and the degree of adverse outcome. Biological pathways are regulated at multiple levels, including transcriptional, post-transcriptional, post-translational, and targeted degradation, each of which can affect the levels and extents of modification of proteins involved in the pathways. Significant alterations of toxicity pathways resulting from changes in regulation at any of these levels therefore are likely to be detectable as alterations in the proteome. We hypothesize that significant correlations between exposures, adverse outcomes, and changes in the proteome have the potential to identify putative toxicity pathways, facilitating selection of candidate targets for high throughput screening, even in the absence of knowledge of either the specific pathways involved or the specific agents inducing the pathway alterations. We explored this hypothesis in BEAS-2B human airway epithelial cells exposed to different concentrations of Ni, Cd, and Cr, alone and in defined mixtures. Levels and phosphorylation status of a variety of signaling pathway proteins and cytokines were measured after 48 hours exposure, together with cytotoxicity. Least Absolute Shrinkage and Selection Operator (LASSO) multiple regression was used to identify a subset of these proteins that constitute a putative toxicity pathway capable of predicting cytotoxicity. The putative toxicity pathway for cytotoxicity of these metals and metal mixtures identified by LASSO is composed of phospho-RPS6KB1, phospho-p53, cleaved CASP3, phospho-MAPK8, IL-10, and Hif-1α. As this approach does not depend on knowledge of the chemical composition of the mixtures, it may be generally useful for identifying sets of proteins predictive of adverse effects for a variety of mixtures, including complex environmental mixtures of unknown composition.
毒性途径已被定义为正常的细胞途径，当因化学物质暴露而受到足够程度的干扰时，会导致不良后果。如果一种暴露将一个或多个正常生物途径改变到导致不良毒性后果的程度，那么在暴露、途径改变程度和不良后果程度之间必然存在显著相关性。生物途径在多个水平上受到调控，包括转录、转录后、翻译后和靶向降解，其中每个水平都可能影响途径中涉及的蛋白质的修饰水平和程度。因此，由这些水平中任何一个的调控变化导致的毒性途径的显著改变很可能可作为蛋白质组的改变被检测到。我们假设，暴露、不良后果与蛋白质组变化之间的显著相关性有潜力识别出假定的毒性途径，有助于选择用于高通量筛选的候选靶点，即使在既不知道所涉及的具体途径也不知道诱导途径改变的具体物质的情况下。我们在暴露于不同浓度的镍、镉和铬单独及特定混合物的BEAS - 2B人气道上皮细胞中探索了这一假设。暴露48小时后测量了多种信号通路蛋白和细胞因子的水平及磷酸化状态，同时测量了细胞毒性。使用最小绝对收缩和选择算子（LASSO）多元回归来识别这些蛋白质的一个子集，该子集构成能够预测细胞毒性的假定毒性途径。通过LASSO鉴定出的这些金属及其混合物细胞毒性的假定毒性途径由磷酸化的RPS6KB1、磷酸化的p53、裂解的CASP3、磷酸化的MAPK8、IL - 10和Hif - 1α组成。由于这种方法不依赖于混合物化学成分的知识，它可能普遍适用于识别预测各种混合物（包括成分未知的复杂环境混合物）不良影响的蛋白质组。
