Jancis E M, Carbone R, Loechner K J, Dannies P S
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
Mol Pharmacol. 1993 Jan;43(1):51-6.
Rhodamine 123 is a fluorescent dye that localizes in mitochondria, is a substrate for the multidrug resistance pump, and is retained for long periods of time by carcinoma cells. 17 beta-Estradiol causes GH4C1 cells (rat pituitary tumor cells) to lose rhodamine 123 fluorescence faster than untreated cells. We found that estradiol induces accumulation of the mRNA for the multidrug resistance pump 3-5-fold, with maximum induction occurring within 1 day at 10(-9) M estradiol. Immunoblot analysis demonstrated that estradiol induces a protein of 150 kDa that reacts with an antibody to P-glycoprotein, the multidrug resistance pump. The reduced retention of rhodamine 123 caused by estradiol is prevented by verapamil and cyclosporin, inhibitors of the pump. A clone resistant to the effects of estradiol on rhodamine 123 has greatly reduced levels of mRNA for the pump. The effect of estradiol is more marked on rhodamine 123 retention than it is on that of rhodamine 110 or tetramethylrhodamine methyl ester. We conclude that estradiol enhances rhodamine 123 efflux by inducing the multidrug resistance gene. The specificity for rhodamine 123, compared with other analogs, may be caused by differences in accessibility to the pump.
罗丹明123是一种定位于线粒体的荧光染料，是多药耐药泵的底物，并且能被癌细胞长时间保留。17β-雌二醇使GH4C1细胞（大鼠垂体瘤细胞）比未处理的细胞更快地丧失罗丹明123荧光。我们发现，雌二醇诱导多药耐药泵的mRNA积累3至5倍，在10^(-9) M雌二醇作用下，最大诱导在1天内出现。免疫印迹分析表明，雌二醇诱导一种150 kDa的蛋白质，该蛋白质与针对多药耐药泵P-糖蛋白的抗体发生反应。维拉帕米和环孢菌素（该泵的抑制剂）可阻止由雌二醇引起的罗丹明123保留减少。对雌二醇对罗丹明123作用具有抗性的克隆，其泵的mRNA水平大大降低。雌二醇对罗丹明123保留的影响比对罗丹明110或四甲基罗丹明甲酯的影响更明显。我们得出结论，雌二醇通过诱导多药耐药基因增强罗丹明123的外排。与其他类似物相比，对罗丹明123的特异性可能是由于该泵的可及性差异所致。
