Kelly Government Solutions , Research Triangle Park , North Carolina 27709 , United States.
Division of the National Toxicology Program , National Institute of Environmental Health Sciences , Research Triangle Park , North Carolina 27709 , United States.
Chem Res Toxicol. 2019 Jul 15;32(7):1384-1401. doi: 10.1021/acs.chemrestox.9b00053. Epub 2019 Jun 18.
Genotoxicity is a critical component of a comprehensive toxicological profile. The Tox21 Program used five quantitative high-throughput screening (qHTS) assays measuring some aspect of DNA damage/repair to provide information on the genotoxic potential of over 10 000 compounds. Included were assays detecting activation of p53, increases in the DNA repair protein ATAD5, phosphorylation of H2AX, and enhanced cytotoxicity in DT40 cells deficient in DNA-repair proteins REV3 or KU70/RAD54. Each assay measures a distinct component of the DNA damage response signaling network; >70% of active compounds were detected in only one of the five assays. When qHTS results were compared with results from three standard genotoxicity assays (bacterial mutation, chromosomal aberration, and micronucleus), a maximum of 40% of known, direct-acting genotoxicants were active in one or more of the qHTS genotoxicity assays, indicating low sensitivity. This suggests that these qHTS assays cannot in their current form be used to replace traditional genotoxicity assays. However, despite the low sensitivity, ranking chemicals by potency of response in the qHTS assays revealed an enrichment for genotoxicants up to 12-fold compared with random selection, when allowing a 1% false positive rate. This finding indicates these qHTS assays can be used to prioritize chemicals for further investigation, allowing resources to focus on compounds most likely to induce genotoxic effects. To refine this prioritization process, models for predicting the genotoxicity potential of chemicals that were active in Tox21 genotoxicity assays were constructed using all Tox21 assay data, yielding a prediction accuracy up to 0.83. Data from qHTS assays related to stress-response pathway signaling (including genotoxicity) were the most informative for model construction. By using the results from qHTS genotoxicity assays, predictions from models based on qHTS data, and predictions from commercial bacterial mutagenicity QSAR models, we prioritized Tox21 chemicals for genotoxicity characterization.
遗传毒性是全面毒理学特征的一个关键组成部分。Tox21 计划使用五种定量高通量筛选（qHTS）测定法来测量 DNA 损伤/修复的某些方面，为超过 10000 种化合物的遗传毒性潜力提供信息。这些测定法包括检测 p53 激活、DNA 修复蛋白 ATAD5 增加、H2AX 磷酸化以及在缺乏 DNA 修复蛋白 REV3 或 KU70/RAD54 的 DT40 细胞中细胞毒性增强的测定法。每个测定法都测量 DNA 损伤反应信号网络的一个不同组成部分；在 5 种测定法中，只有一种测定法检测到 >70%的活性化合物。当 qHTS 结果与三种标准遗传毒性测定法（细菌突变、染色体畸变和微核）的结果进行比较时，在一种或多种 qHTS 遗传毒性测定法中，最多有 40%的已知直接作用遗传毒性物质是活跃的，这表明敏感性较低。这表明这些 qHTS 测定法不能以其当前形式替代传统的遗传毒性测定法。然而，尽管敏感性较低，但根据 qHTS 测定法的反应效力对化学物质进行排序，与随机选择相比，当允许 1%的假阳性率时，可富集到高达 12 倍的遗传毒性物质。这一发现表明，这些 qHTS 测定法可用于优先考虑进一步研究的化学物质，从而使资源集中在最有可能引起遗传毒性作用的化合物上。为了改进这种优先级排序过程，使用所有 Tox21 测定法数据构建了在 Tox21 遗传毒性测定法中活跃的化学物质的遗传毒性潜力预测模型，预测准确性高达 0.83。与应激反应途径信号（包括遗传毒性）相关的 qHTS 测定法的数据对于模型构建最有信息。通过使用 qHTS 遗传毒性测定法的结果、基于 qHTS 数据的模型的预测以及商业细菌致突变性 QSAR 模型的预测，我们对 Tox21 化学物质进行了遗传毒性特征的优先级排序。
