Matsushima Soichiro, Maeda Kazuya, Kondo Chihiro, Hirano Masaru, Sasaki Makoto, Suzuki Hiroshi, Sugiyama Yuichi
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
J Pharmacol Exp Ther. 2005 Sep;314(3):1059-67. doi: 10.1124/jpet.105.085589. Epub 2005 May 18.
Until recently, it was generally believed that the transport of various organic anions across the bile canalicular membrane was mainly mediated by multidrug resistance-associated protein 2 (MRP2/ABCC2). However, a number of new reports have shown that some organic anions are also substrates of multidrug resistance 1 (MDR1/ABCB1) and/or breast cancer resistance protein (BCRP/ABCG2), implying MDR1 and BCRP could also be involved in the biliary excretion of organic anions in humans. In the present study, we constructed new double-transfected Madin-Darby canine kidney II (MDCKII) cells expressing organic anion-transporting polypeptide 1B1 (OATP1B1)/MDR1 and OATP1B1/BCRP, and we investigated the transcellular transport of four kinds of organic anions, estradiol-17beta-d-glucuronide (EG), estrone-3-sulfate (ES), pravastatin (PRA), and cerivastatin (CER), to identify which efflux transporters mediate the biliary excretion of compounds using double-transfected cells. We observed the vectorial transport of EG and ES in all the double transfectants. MRP2 showed the highest efflux clearance of EG among these efflux transporters, whereas BCRP-mediated clearance of ES was the highest in these double transfectants. In addition, two kinds of 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors, CER and PRA, were also substrates of all these efflux transporters. The rank order of the efflux clearance of PRA mediated by each transporter was the same as that of EG, whereas the contribution of MDR1 to the efflux of CER was relatively greater than for PRA. This experimental system is very useful for identifying which transporters are involved in the biliary excretion of organic anions that cannot easily penetrate the plasma membrane.
直到最近，人们普遍认为各种有机阴离子跨胆小管膜的转运主要由多药耐药相关蛋白2（MRP2/ABCC2）介导。然而，一些新的报告表明，一些有机阴离子也是多药耐药1（MDR1/ABCB1）和/或乳腺癌耐药蛋白（BCRP/ABCG2）的底物，这意味着MDR1和BCRP也可能参与人体中有机阴离子的胆汁排泄。在本研究中，我们构建了新的双转染的马-达二氏犬肾II（MDCKII）细胞，其表达有机阴离子转运多肽1B1（OATP1B1）/MDR1和OATP1B1/BCRP，并且我们研究了四种有机阴离子，雌二醇-17β -d -葡萄糖醛酸苷（EG）、雌酮-3 -硫酸盐（ES）、普伐他汀（PRA）和西立伐他汀（CER）的跨细胞转运，以使用双转染细胞确定哪些外排转运体介导化合物的胆汁排泄。我们在所有双转染细胞中观察到了EG和ES的向量转运。在这些外排转运体中，MRP2对EG的外排清除率最高，而在这些双转染细胞中，BCRP介导的ES清除率最高。此外，两种3 -羟基-3 -甲基戊二酰辅酶A还原酶抑制剂，CER和PRA，也是所有这些外排转运体的底物。每种转运体介导的PRA外排清除率的排序与EG相同，而MDR1对CER外排的贡献相对大于PRA。该实验系统对于确定哪些转运体参与不易穿透质膜的有机阴离子的胆汁排泄非常有用。
