Glucocorticoids are steroid hormones that have systemic effects that are mediated by the glucocorticoid receptor. Environmental chemicals that disrupt glucocorticoid receptor signaling and/or glucocorticoid homeostasis could adversely affect the health of human and nonhuman vertebrates. A major challenge in identifying environmental chemicals that alter glucocorticoid receptor signaling and/or glucocorticoid homeostasis is a lack of adequate screening methods. We developed a cell‐based bioassay to measure total glucocorticogenic activity (TGA) of environmental chemicals and human serum. Human MDA‐MB‐231 breast cancer cells were stably transfected with a luciferase reporter gene driven by 3 tandem glucocorticoid‐response elements. Dose–response curves for 6 glucocorticoids and 4 non‐glucocorticoid steroid hormones were generated to evaluate the specificity of the bioassay. Cells were also optimized to measure TGA of 176 structurally diverse environmental chemicals and human serum samples in a high‐throughput format. Reporter activity was glucocorticoid‐specific and induced 400‐fold by 1 μM dexamethasone. Furthermore, 3 of the screened chemicals (3,4,4′‐trichlorocarbanilide, isopropyl‐N‐phenylcarbamate, and benzothiazole derivative 2‐[4‐chlorophenyl]‐benzothiazole) potentiated cortisol‐induced glucocorticoid receptor activity. Serum TGA estimates from the bioassay were highly correlated with a cortisol enzyme‐linked immunosorbent assay. The present study establishes an in vitro method to rapidly screen environmental chemicals and human serum for altered glucocorticogenic activity. Future studies can utilize this tool to quantify the joint effect of endogenous glucocorticoids and environmental chemicals. Environ Toxicol Chem 2021;40:177–186. © 2020 SETAC

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基于细胞的生物测定法筛选环境化学品和人血清的总糖皮质激素活性

糖皮质激素是类固醇激素，具有由糖皮质激素受体介导的全身作用。破坏糖皮质激素受体信号和/或糖皮质激素稳态的环境化学物质可能对人类和非人类脊椎动物的健康产生不利影响。识别改变糖皮质激素受体信号传导和/或糖皮质激素稳态的环境化学物质的主要挑战是缺乏适当的筛选方法。我们开发了一种基于细胞的生物测定法来测量环境化学品和人血清的总糖皮质激素活性 (TGA)。人 MDA-MB-231 乳腺癌细胞被 3 个串联糖皮质激素反应元件驱动的荧光素酶报告基因稳定转染。生成了 6 种糖皮质激素和 4 种非糖皮质激素类固醇激素的剂量反应曲线，以评估生物测定的特异性。还优化了细胞，以高通量形式测量 176 种结构多样的环境化学品和人血清样品的 TGA。报告活性是糖皮质激素特异性的，1 μM 地塞米松可诱导 400 倍。此外，筛选出的 3 种化学品（3,4,4'-三氯二氯苯胺、异丙基-N-苯基氨基甲酸酯和苯并噻唑衍生物 2-[4-氯苯基]-苯并噻唑）增强皮质醇诱导的糖皮质激素受体活性。来自生物测定的血清 TGA 估计值与皮质醇酶联免疫吸附测定高度相关。本研究建立了一种体外方法来快速筛选环境化学物质和人血清以改变糖皮质激素活性。未来的研究可以利用这个工具来量化内源性糖皮质激素和环境化学物质的联合作用。环境毒物化学2021；40：177–186。© 2020 SETAC