Yoshinari Kouichi, Ueda Rika, Kusano Kazutomi, Yoshimura Tsutomu, Nagata Kiyoshi, Yamazoe Yasushi
Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
Biochem Pharmacol. 2008 Jul 1;76(1):139-45. doi: 10.1016/j.bcp.2008.04.005. Epub 2008 Apr 16.
Omeprazole induces human CYP1A1 and CYP1A2 in human hepatoma cells and human liver. Aryl hydrocarbon receptor (AHR) is shown to be involved in this induction. However, its precise molecular mechanism remains unknown because the chemical activates AHR without its direct binding in contrast to typical AHR ligands such as 3-methylcholanthrene (3MC) and beta-naphthoflavone (BNF). Human CYP1A1 and CYP1A2 genes are located in a head-to-head orientation sharing about 23 kb 5'-flanking region. Recently, we succeeded to measure CYP1A1 and CYP1A2 transcriptional activities simultaneously using dual reporter gene constructs containing the 23 kb sequence. In this study, transient transfection assays have been performed using numbers of single and dual reporter constructs to identify omeprazole-responsive region for CYP1A1 and CYP1A2 induction. Reporter assays with deletion constructs have demonstrated that the omeprazole-induced expression of both CYP1A1 and CYP1A2 is mediated via the common regulatory region containing multiple AHR-binding motifs (the nucleotides from -464 to -1829 of human CYP1A1), which is identical with the region for BNF and 3MC induction. Interestingly, omeprazole activated the transcription of CYP1A1 and CYP1A2 to similar extents while BNF and 3MC preferred CYP1A1 expression. We have also found that primaquine is an omeprazole-like CYP1A inducer, while lansoprazole and albendazole are 3MC/BNF-like in terms of the CYP1A1/CYP1A2 preference. The present results suggest that omeprazole as well as BNF and 3MC activates both human CYP1A1 and CYP1A2 expression through the common regulatory region despite that omeprazole may involve a different cellular signal(s) from BNF and 3MC.
奥美拉唑可在人肝癌细胞和人肝脏中诱导人CYP1A1和CYP1A2。已表明芳烃受体（AHR）参与了这种诱导作用。然而，其确切的分子机制仍不清楚，因为与典型的AHR配体如3-甲基胆蒽（3MC）和β-萘黄酮（BNF）不同，该化学物质在不直接结合的情况下激活AHR。人CYP1A1和CYP1A2基因以头对头的方向定位，共享约23 kb的5'侧翼区域。最近，我们成功地使用包含23 kb序列的双报告基因构建体同时测量了CYP1A1和CYP1A2的转录活性。在本研究中，使用了许多单报告基因和双报告基因构建体进行瞬时转染试验，以鉴定CYP1A1和CYP1A2诱导的奥美拉唑反应区域。缺失构建体的报告基因分析表明，奥美拉唑诱导的CYP1A1和CYP1A2表达均通过包含多个AHR结合基序的共同调控区域介导（人CYP1A1的-464至-1829核苷酸），该区域与BNF和3MC诱导的区域相同。有趣的是，奥美拉唑激活CYP1A1和CYP1A2转录的程度相似，而BNF和3MC更倾向于CYP1A1表达。我们还发现伯氨喹是一种类似奥美拉唑的CYP1A诱导剂，而兰索拉唑和阿苯达唑在CYP1A1/CYP1A2偏好方面类似于3MC/BNF。目前的结果表明，尽管奥美拉唑可能涉及与BNF和3MC不同的细胞信号，但它与BNF和3MC一样通过共同的调控区域激活人CYP1A1和CYP1A2的表达。
