Zhou Lin, Naraharisetti Suresh Babu, Wang Honggang, Unadkat Jashvant D, Hebert Mary F, Mao Qingcheng
Department of Pharmaceutics, School of Pharmacy, Box 357610, University of Washington, Seattle, WA 98195, USA.
Mol Pharmacol. 2008 Mar;73(3):949-59. doi: 10.1124/mol.107.041616. Epub 2007 Dec 13.
Breast cancer resistance protein (BCRP) is most abundantly expressed in the apical membrane of placental syncytiotrophoblasts, suggesting that it may protect the fetus by impeding drug penetration across the placental barrier. Glyburide (GLB) is an antidiabetic drug routinely used to treat gestational diabetes. In this study, we first determined whether GLB is a BCRP/Bcrp1 substrate. The intracellular [(3)H]GLB concentrations in Madin-Darby canine kidney (MDCK)/BCRP cells were significantly lower than those in MDCK/vector cells. The addition of 10 muM fumitremorgin C, a specific BCRP inhibitor, significantly increased the intracellular [(3)H]GLB concentrations approximately 2-fold in MDCK/BCRP cells, but it had no effect in MDCK/vector cells. Similar results were obtained using MDCKII parent and MDCKII/Bcrp1 cells. GLB was also shown to be a BCRP/Bcrp1 substrate in transwell transport experiments. We then examined whether Bcrp1 limits fetal distribution of GLB in the pregnant mouse. GLB was administered by retro-orbital injection to the wild-type and Bcrp1(-/-) pregnant mice. The maternal plasma samples and fetuses were collected at various times (0.5-240 min) after drug administration. The GLB concentrations in the maternal plasma samples and homogenates of fetal tissues were determined by high-performance liquid chromatography/mass spectrometry. Although the maternal plasma area under the concentration-time curves (AUCs) of GLB in the wild-type and Bcrp1(-/-) pregnant mice were comparable, the fetal AUC of GLB in the Bcrp1(-/-) pregnant mice was approximately 2 times greater than that in the wild-type pregnant mice. These results suggest that GLB is a BCRP/Bcrp1 substrate, and Bcrp1 significantly limits fetal distribution of GLB in the pregnant mouse, but it has only a minor effect on the systemic clearance of the drug.
乳腺癌耐药蛋白（BCRP）在胎盘合体滋养层细胞的顶膜中表达最为丰富，这表明它可能通过阻止药物穿过胎盘屏障来保护胎儿。格列本脲（GLB）是一种常用于治疗妊娠期糖尿病的抗糖尿病药物。在本研究中，我们首先确定GLB是否为BCRP/Bcrp1底物。Madin-Darby犬肾（MDCK）/BCRP细胞内的[³H]GLB浓度显著低于MDCK/载体细胞。添加10μM的特异性BCRP抑制剂夫马洁林C，可使MDCK/BCRP细胞内的[³H]GLB浓度显著增加约2倍，但对MDCK/载体细胞无影响。使用MDCKII亲本细胞和MDCKII/Bcrp1细胞也得到了类似结果。在跨膜转运实验中，GLB也被证明是BCRP/Bcrp1底物。然后，我们研究了Bcrp1是否限制了GLB在妊娠小鼠体内向胎儿的分布。通过眶后注射将GLB给予野生型和Bcrp1基因敲除（Bcrp1⁻/⁻）的妊娠小鼠。在给药后的不同时间点（0.5 - 240分钟）收集母体血浆样本和胎儿。通过高效液相色谱/质谱法测定母体血浆样本和胎儿组织匀浆中的GLB浓度。尽管野生型和Bcrp1⁻/⁻妊娠小鼠体内GLB的母体血浆浓度-时间曲线下面积（AUC）相当，但Bcrp1⁻/⁻妊娠小鼠体内GLB的胎儿AUC约为野生型妊娠小鼠的2倍。这些结果表明，GLB是BCRP/Bcrp1底物，并且Bcrp1显著限制了GLB在妊娠小鼠体内向胎儿的分布，但对该药物的全身清除率影响较小。
