The role of pregnane X receptor in 2-acetylaminofluorene-mediated induction of drug transport and -metabolizing enzymes in mice
The role of pregnane X receptor in 2-acetylaminofluorene-mediated induction of drug transport and -metabolizing enzymes in mice
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DOI：
10.1124/dmd.105.006197
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发表时间：
2006-03-01
影响因子：
3.9
通讯作者：
Piquette-Miller, M
中科院分区：
文献类型：
--
作者：
Anapolsky, A;Teng, S;Piquette-Miller, M
β-环糊精X受体（PXR）的激活介导了几种药物转运蛋白和β-代谢酶的诱导。体外研究报告称，这些基因中的几个在暴露于肝癌原2-乙酰氨基芴（2-AAF）后被诱导。因此，我们假设PXR可能在2-AAF体内诱导基因表达中发挥作用。我们检测了药物代谢酶CYP 1A 2和CYP 3A 11以及药物转运蛋白乳腺癌耐药蛋白（BCRP）、MRP 2和OATP 2的表达。每天给野生型（PXR-/-）和无PXR（PXR-/-）C57 BL/6小鼠注射悬浮于玉米油中的150或300 mg/kg 2-AAF（i. p.），持续7天，而对照组接受玉米油载体。通过逆转录-聚合酶链反应测量从肝脏分离的mRNA水平，并将其标准化为β-肌动蛋白。PXR+/+小鼠给药导致MRP 2、OATP 2、BCRP、CYP 3A 11和CYP 1A 2的剂量依赖性诱导增加2至4倍（p < 0.001），但在PXR-/-小鼠中未观察到诱导。在2-AAF处理的PXR-/-小鼠中观察到PXR mRNA的诱导。此外，在与人或大鼠PXR共转染的HepG 2细胞中观察到CYP 3A 4启动子构建体活性的剂量依赖性增加，表明2-AAF确实激活PXR。这些结果表明，PXR是负责2-AAF介导的诱导药物外排转运蛋白和生物转化酶在肝脏中。此外，新的研究结果表明，PXR在调节小鼠的药物外排转运蛋白BCRP中发挥作用。
Activation of the pregnane X receptor (PXR) mediates the induction of several drug transporters and -metabolizing enzymes. In vitro studies have reported that several of these genes are induced after exposure to the hepatocarcinogen, 2-acetylaminofluorene (2-AAF). Thus, we hypothesized that PXR may play a role in the in vivo induction of gene expression by 2-AAF. We examined the expression of the drug-metabolizing enzymes CYP1A2 and CYP3A11 and the drug transporters breast cancer resistance protein (BCRP), MRP2, and OATP2. Wild-type (PXR-/-) and PXR-null (PXR-/-) C57BL/6 mice were injected daily for 7 days with 150 or 300 mg/kg 2-AAF suspended in corn oil (i.p.), whereas the control group received corn oil vehicle. Levels of mRNA isolated from liver were measured by reverse transcription-polymerase chain reaction and normalized to beta-actin. Treatment of PXR+/+ mice resulted in a dose-dependent 2- to 4-fold induction (p < 0.001) of MRP2, OATP2, BCRP, CYP3A11, and CYP1A2, but no induction was observed in PXR-/- mice. Induction of PXR mRNA was observed in the 2-AAF-treated PXR-/- mice. Furthermore, a dose-dependent increase in CYP3A4 promoter construct activity was observed in HepG2 cells cotransfected with human or rat PXR, indicating that 2-AAF does indeed activate PXR. These results suggest that PXR is responsible for 2-AAF-mediated induction of drug efflux transporters and biotransformation enzymes in the liver. Moreover, novel findings demonstrate that PXR plays a role in regulation of the drug efflux transporter, BCRP, in mice.