Faculty of Pharmacy, Rhodes University, Grahamstown, South Africa.
Biomedical Biotechnology Research Unit, Rhodes University, Grahamstown, South Africa.
Drug Chem Toxicol. 2020 Nov;43(6):656-662. doi: 10.1080/01480545.2019.1585869. Epub 2019 Mar 18.
Metabolically induced drug-toxicity is a major cause of drug failure late in drug optimization phases. Accordingly, metabolic profiling of compounds is being introduced at earlier stages of the drug discovery pipeline. An increasingly common method to obtain these profiles is through overexpression of key CYP450 metabolic enzymes in immortalized liver cells, to generate competent hepatocyte surrogates. Enhanced cytotoxicity is presumed to be due to toxic metabolite production via the overexpressed enzyme. However, metabolically induced toxicity is a complex multi-parameter phenomenon and the potential background contribution to metabolism arising from the use of liver cells which endogenously express CYP450 isoforms is consistently overlooked. In this study, we sought to reduce the potential background interference by applying this methodology in kidney-derived HEK293 cells which lack endogenous CYP450 expression. Overexpression of CYP3A4 resulted in increased HEK293 proliferation, while exposure to four compounds with reported metabolically induced cytotoxicity in liver-derived cells overexpressing CYP3A4 resulted in no increase in cytotoxicity. Our results indicate that overexpression of a single CYP450 isoform in hepatic cell lines may not be a reliable method to discriminate which enzymes are responsible for metabolic induced cytotoxicity.
代谢诱导的药物毒性是药物优化后期药物失败的主要原因。因此，在药物发现管道的早期阶段引入了化合物的代谢分析。获得这些图谱的一种越来越常见的方法是通过在永生化肝细胞中过度表达关键的 CYP450 代谢酶，生成有能力的肝细胞替代物。假定增强的细胞毒性是由于通过过度表达的酶产生有毒代谢物。然而，代谢诱导的毒性是一种复杂的多参数现象，并且由于使用内源性表达 CYP450 同工型的肝细胞而产生的潜在背景对代谢的贡献一直被忽视。在这项研究中，我们试图通过在缺乏内源性 CYP450 表达的肾源性 HEK293 细胞中应用这种方法来减少潜在的背景干扰。CYP3A4 的过度表达导致 HEK293 细胞增殖增加，而暴露于四种在过表达 CYP3A4 的肝源性细胞中报告具有代谢诱导细胞毒性的化合物不会导致细胞毒性增加。我们的结果表明，在肝系细胞系中过度表达单一 CYP450 同工型可能不是区分哪些酶负责代谢诱导细胞毒性的可靠方法。
