Genetic toxicology is an essential component of compound safety assessment. In the face of a barrage of new compounds, higher throughput, less ethically divisive in vitro approaches capable of effective, human-relevant hazard identification and prioritisation are increasingly important. One such approach is the ToxTracker assay, which utilises murine stem cell lines equipped with green fluorescent protein (GFP)-reporter gene constructs that each inform on distinct aspects of cellular perturbation. Encouragingly, ToxTracker has shown improved sensitivity and specificity for the detection of known in vivo genotoxicants when compared to existing ‘standard battery’ in vitro tests. At the current time however, quantitative genotoxic potency correlations between ToxTracker and well-recognised in vivo tests are not yet available. Here we use dose–response data from the three DNA-damage-focused ToxTracker endpoints and from the in vivo micronucleus assay to carry out quantitative, genotoxic potency estimations for a range of aromatic amine and alkylating agents using the benchmark dose (BMD) approach. This strategy, using both the exponential and the Hill BMD model families, was found to produce robust, visually intuitive and similarly ordered genotoxic potency rankings for 17 compounds across the BSCL2-GFP, RTKN-GFP and BTG2-GFP ToxTracker endpoints. Eleven compounds were similarly assessed using data from the in vivo micronucleus assay. Cross-systems genotoxic potency correlations for the eight matched compounds demonstrated in vitro–in vivo correlation, albeit with marked scatter across compounds. No evidence for distinct differences in the sensitivity of the three ToxTracker endpoints was found. The presented analyses show that quantitative potency determinations from in vitro data enable more than just qualitative screening and hazard identification in genetic toxicology.

中文翻译：

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遗传毒性效力估计的经验比较：体外 DNA 损伤 ToxTracker 终点与体内微核试验

遗传毒理学是化合物安全性评估的重要组成部分。面对一连串的新化合物，更高的通量、更少伦理分歧的体外方法能够有效地识别与人类相关的危害并确定优先级变得越来越重要。一种这样的方法是 ToxTracker 检测，它利用配备绿色荧光蛋白 (GFP) 报告基因构建体的小鼠干细胞系，每个构建体都可以告知细胞扰动的不同方面。令人鼓舞的是，与现有的“标准电池”体外测试相比，ToxTracker 在检测已知体内基因毒物方面表现出更高的灵敏度和特异性。然而，目前尚无 ToxTracker 与公认的体内测试之间的定量遗传毒性效力相关性。在这里，我们使用来自三个以 DNA 损伤为重点的 ToxTracker 终点和体内微核试验的剂量反应数据，使用基准剂量 (BMD) 方法对一系列芳香胺和烷化剂进行定量的遗传毒性效力估计。发现该策略同时使用指数和 Hill BMD 模型系列，对 BSCL2-GFP、RTKN-GFP 和 BTG2-GFP ToxTracker 端点的 17 种化合物产生稳健、视觉直观和类似排序的基因毒性效力排名。使用来自体内微核测定的数据类似地评估了十一种化合物。八种匹配化合物的跨系统遗传毒性效力相关性证明了体外 - 体内相关性，尽管化合物之间存在显着分散。没有发现三个 ToxTracker 端点的敏感性存在明显差异的证据。所提出的分析表明，从体外数据中定量测定效力不仅仅是遗传毒理学中的定性筛选和危害识别。