Drug Safety and Pharmacokinetics Laboratories (H.T., J.Y., M.T., H.E.), Pharmacology Laboratories (S.K.), and Chemistry Laboratories (M.H.), Taisho Pharmaceutical Co., Ltd., Saitama, Japan
Drug Safety and Pharmacokinetics Laboratories (H.T., J.Y., M.T., H.E.), Pharmacology Laboratories (S.K.), and Chemistry Laboratories (M.H.), Taisho Pharmaceutical Co., Ltd., Saitama, Japan.
Drug Metab Dispos. 2021 Jan;49(1):20-30. doi: 10.1124/dmd.120.000124. Epub 2020 Oct 21.
Hypoxia-inducible factor (HIF) is associated with the expression of CYP, but the underlying mechanism remains uncertain. In this study, we investigated the effect of HIF- stabilization caused by novel prolyl hydroxylase domain (PHD) 2 inhibitors, which are HIF- stabilizers that mimic hypoxia, on the expressions of CYP1A2, CYP2B6, and CYP3A4 in human hepatocytes. An mRNA expression analysis of human hepatocytes treated with PHD2 inhibitors for 72 hours showed the downregulation of genes encoding CYP1A2, CYP2B6, and CYP3A4. The mRNA repressions were accompanied with an increase in erythropoietin protein, a marker of HIF- stabilization, indicating that HIF- stabilization was involved in the downregulation of the CYP isoforms. To understand the underlying mechanisms, we assessed the relationship between the expressions of the CYP isoforms and those of their regulating transcription factors [aryl hydrocarbon receptor (AhR), AhR nuclear translocator (ARNT), constitutive androstane receptor (CAR), pregnane X receptor (PXR), and retinoid X receptor (RXR)] in human hepatocytes treated with the HIF- stabilizers. As a result, the mRNA level of AhR did not decrease, although ARNT expression was repressed. On the other hand, the mRNA expression levels of CAR, PXR, and RXR were repressed and closely associated with those of CYP2B6 and CYP3A4. Although the underlying mechanism of the downregulation for CYP1A2 remains unclear, the presently reported results suggest that the downregulation of CYP2B6 and CYP3A4 via HIF- stabilization is caused by a decrease in the expressions of CAR, PXR, and RXR. SIGNIFICANCE STATEMENT: We showed that hypoxia-inducible factor (HIF)-α stabilization downregulates CYP1A2, CYP2B6, and CYP3A4 using prolyl hydroxylase domain 2 inhibitors, which are HIF-α stabilizers, as a new tool to mimic hypoxia in human hepatocytes. To understand the underlying mechanisms, we assessed the relationship between the expressions of the CYP isoforms and those of their regulating transcription factors. Our findings would contribute to a better understanding of the hypoxia-triggered regulatory mechanism of drug-metabolizing enzymes in human hepatocytes.
缺氧诱导因子 (HIF) 与 CYP 的表达有关，但潜在机制尚不清楚。在这项研究中，我们研究了新型脯氨酰羟化酶结构域 (PHD) 2 抑制剂引起的 HIF-稳定化对人肝细胞中 CYP1A2、CYP2B6 和 CYP3A4 表达的影响。用 PHD2 抑制剂处理 72 小时的人肝细胞的 mRNA 表达分析显示，编码 CYP1A2、CYP2B6 和 CYP3A4 的基因下调。mRNA 抑制伴随着促红细胞生成素蛋白的增加，这是 HIF-稳定化的标志物，表明 HIF-稳定化参与了 CYP 同工酶的下调。为了了解潜在的机制，我们评估了 CYP 同工酶的表达与它们在人肝细胞中调节转录因子 [芳烃受体 (AhR)、AhR 核转位蛋白 (ARNT)、组成型雄甾烷受体 (CAR)、孕烷 X 受体 (PXR) 和视黄酸 X 受体 (RXR)] 之间的关系。结果表明，虽然 ARNT 表达受到抑制，但 AhR 的 mRNA 水平并没有降低。另一方面，CAR、PXR 和 RXR 的 mRNA 表达水平受到抑制，与 CYP2B6 和 CYP3A4 的表达密切相关。虽然 CYP1A2 下调的潜在机制尚不清楚，但目前的研究结果表明，通过 HIF-稳定化下调 CYP2B6 和 CYP3A4 是由于 CAR、PXR 和 RXR 的表达减少所致。意义陈述：我们使用脯氨酰羟化酶结构域 2 抑制剂（HIF-α 稳定剂）作为模拟人肝细胞缺氧的新工具，显示缺氧诱导因子 (HIF)-α 稳定化会下调 CYP1A2、CYP2B6 和 CYP3A4。为了了解潜在机制，我们评估了 CYP 同工酶的表达与它们调节转录因子的表达之间的关系。我们的发现将有助于更好地理解人肝细胞中药物代谢酶的缺氧触发调节机制。
