Aryl hydrocarbon receptor activation and cytochrome P450 1A induction by the mitogen-activated protein kinase inhibitor U0126 in hepatocytes
Aryl hydrocarbon receptor activation and cytochrome P450 1A induction by the mitogen-activated protein kinase inhibitor U0126 in hepatocytes
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DOI：
10.1124/mol.65.4.934
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发表时间：
2004-04-01
影响因子：
3.6
通讯作者：
Guillouzo, A
中科院分区：
文献类型：
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作者：
Andrieux, L;Langouet, S;Guillouzo, A
芳烃受体（AhR）参与各种过程，如细胞色素P450（P450）1A诱导后，外源性暴露。它也被认为在细胞增殖和分化中起主要作用。最近的证据表明，AhR功能和丝裂原活化蛋白激酶（MAPK）级联之间的串扰。我们现在报告，1，4-二氨基-2，3-二氰基-1，4-双[2-氨基苯硫基]丁二烯（U 0126），一种特异性MAPK激酶（MEK）MEK 1/2抑制剂，在mRNA和蛋白水平上均显著增加大鼠原代肝细胞和人肝癌细胞系中CYP 1A 1的表达，并与酶活性的显著增加相关。这种诱导独立于MEK/细胞外信号调节激酶（ERK）激活，并且在ERK 1和ERK 2表达的情况下发生。U 0126的作用是通过其反式激活异生素反应元件（XRE）驱动的基因的能力介导的，如在人B16 A2肝癌细胞系中用XRE驱动的荧光素酶构建体的转染试验所证明的。CYP 1A 1的调制被废除的共同治疗与白藜芦醇，一个既定的AhR拮抗剂，主张AhR激活U 0126。通过使用兔肝胞质溶胶的直接体外配体结合竞争试验证明了这种作用，表明该化合物结合AhR的EC 50 = 25 x 10（-6）M。此外，我们证明了U 0126是几种P450的底物，包括人CYP 1A 2，-1A1和-1B1。我们的结论是，广泛使用的MEK/ERK的特异性抑制剂，U 0126，也作为一个有效的AhR激活剂和相关基因的诱导剂。对AhR的这种作用可能对先前归因于MAPK抑制的生物学功能产生影响。
The aryl hydrocarbon receptor (AhR) is involved in various processes such as cytochrome P450 (P450) 1A induction after xenobiotic exposure. It is also considered to play a major role in cell proliferation and differentiation. Recent evidences have suggested a cross-talk between AhR functions and the mitogen-activated protein kinase (MAPK) cascade. We now report that 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio] butadiene (U0126), a specific inhibitor of MAPK kinase (MEK) MEK1/2, elicits a marked increase in CYP1A1 expression at both mRNA and protein levels associated with a significant increase of enzyme activity in primary rat hepatocytes and a human hepatoma cell line. This induction occurred independently of MEK/extracellular signal-regulated kinase (ERK) activation and in the absence of ERK1 and ERK2 expression. The effect of U0126 was mediated by its ability to transactivate xenobiotic responsive element (XRE)-driven genes, as demonstrated by transfection assays with an XRE-driven luciferase construct in the human B16A2 hepatoma cell line. CYP1A1 modulation was abolished by a cotreatment with resveratrol, an established AhR antagonist, arguing for AhR activation by U0126. Such an effect was demonstrated by direct in vitro ligand binding competition assays using rabbit liver cytosol, showing that this compound binds AhR with an EC50 = 25 x 10(-6) M. Moreover, we demonstrated that U0126 is a substrate for several P450s including human CYP1A2, -1A1, and -1B1. We conclude that the widely used specific inhibitor of MEK/ERK, U0126, also acts as a potent AhR activator and an inducer of related genes. Such effects on the AhR may have an impact on biological functions attributed previously to MAPK inhibition.