Selection of drugs to test the specificity of the Tg.AC assay by screening for induction of the gadd153 promoter in vitro.
Selection of drugs to test the specificity of the Tg.AC assay by screening for induction of the gadd153 promoter in vitro.
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DOI：
10.1093/toxsci/kfg113
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发表时间：
2003-08
期刊：
影响因子：
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通讯作者：
K. Thompson;F. Sistare
中科院分区：
文献类型：
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作者：
K. Thompson;F. Sistare
使用转基因小鼠改变与致癌有关的基因表达的化学物质的致癌性短期测试是在啮齿动物身上进行两年剂量研究的有吸引力的替代方案。接受性能评估水平最高的模型包括P53(+/-)、rasH2、Xpa/P53(+/-)和Tg.AC小鼠。为了在监管环境中使用这些模型来评估药物的致癌潜力，重要的是在使用具有广泛药理活性的药物的研究的基础上，建立检测特异性和阳性预测性的保证。为此，99种非致癌药物根据它们在体外诱导试验中的活性与Tg.AC试验(在HepG2细胞中诱导gadd153启动子的诱导)中的阳性反应相关的活性而被优先考虑。此外，还测量了两种对Tg.AC活性预测较低的检测方法(c-fos和zeta-珠蛋白基因启动子的诱导)。9%的筛选药物诱导gadd153启动子至少增加四倍。在Tg.AC分析中，有几个标准被用来选择随后进行体内测试的候选者：(1)药物在适当的皮肤涂料载体中的足够溶解度以引起全身毒性，(2)药物诱导gadd153启动子的水平，(3)药物的体外效力，以及(4)为期6个月的研究所需的药物成本。基于这些标准，从药物数据库中的99种啮齿动物非致癌物质中选择了阿米洛利、双嘧达莫和乙胺嘧啶，以测试Tg.AC试验的特异性。
Short-term assays for carcinogenicity testing of chemicals that use transgenic mice designed to have altered expression of genes mechanistically relevant to carcinogenesis are attractive alternatives to two-year dosing studies in rodents. The models that have been the received the greatest level of performance evaluation include p53(+/-), rasH2, Xpa/p53(+/-), and Tg.AC mice. For use of these models in a regulatory setting to evaluate the carcinogenic potential of pharmaceuticals, it is important to establish an assurance of assay specificity and positive predictivity based on studies using drugs with a wide spectrum of pharmacologic activity. For this purpose, 99 noncarcinogenic drugs were prioritized based on their activity in an in vitro induction assay correlative with a positive response in the Tg.AC assay (induction of the gadd153 promoter in HepG2 cells). Activities in two assays less predictive of Tg.AC activity (induction of c-fos and zeta-globin gene promoters) were also measured. Nine percent of the screened drugs induced the gadd153 promoter by at least fourfold. Several criteria were used to select candidates for subsequent in vivo testing in the Tg.AC assay: (1) sufficient drug solubility in appropriate skin paint vehicles to elicit systemic toxicity, (2) the level of induction of the gadd153 promoter by the drug, (3) the in vitro potency of the drug, and (4) the cost of the drug required for a 6-month study. Based on these criteria, amiloride, dipyridamole, and pyrimethamine were selected from 99 rodent noncarcinogens in a drug database for testing the specificity of the Tg.AC assay.