Laboratory of Cell Biology (J.B., M.D.H., M.M.G.), Cancer Therapeutics Branch (R.W.R., S.E.B.), Collaborative Protein Technology Resource (M.A.H., J.-Q.C.), Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
Drug Metab Dispos. 2013 Oct;41(10):1805-12. doi: 10.1124/dmd.113.053140. Epub 2013 Jul 18.
ABCG2 (also known as breast cancer resistance protein) is an ATP-binding cassette (ABC) transporter localized to the plasma membrane where it mediates the efflux of xenobiotics, including potential therapeutics. Studies investigating Abcg2 function at the blood-brain barrier in mouse models are often compared with human ABCG2 function. It is critical to understand the nature of species differences between mouse and human ABCG2, since extrapolations are made from murine data to humans. Two independent drug-selected cell line pairs expressing human or mouse ABCG2 were compared for efflux of fluorescent substrates using flow cytometry. To this end, we developed and characterized a new mouse Abcg2-expressing subline that demonstrated efflux of known fluorescent ABCG2 substrates and increased resistance to mitoxantrone, which is reduced in the presence of the ABCG2 inhibitor Ko143. Our results indicate that the substrate specificity of human and mouse ABCG2 is very similar. We identified a new human and mouse ABCG2 substrate, a porphyrin analog, purpurin-18 (Pp-18), which is not a substrate for P-glycoprotein or multidrug resistance protein 1. The ability of inhibitors to block efflux activity of ABCG2 was assessed using Pp-18. Inhibitors also demonstrated similar effects on human and mouse ABCG2. Chrysin, benzoflavone, and cyclosporin A inhibited Pp-18 efflux in both human and mouse ABCG2. The similarity of the substrate and inhibitor specificity of human and mouse ABCG2 supports interpretation of mouse models in understanding the clinical, pharmacological, and physiologic roles of ABCG2.
ABCG2(也称为乳腺癌耐药蛋白)是一种位于质膜上的 ATP 结合盒(ABC)转运体,可介导包括潜在治疗药物在内的外源性物质的外排。在小鼠模型中研究 ABCG2 在血脑屏障中的功能的研究通常与人类 ABCG2 功能进行比较。了解小鼠和人类 ABCG2 之间物种差异的性质至关重要,因为从鼠类数据推断到人类。使用流式细胞术比较了表达人或鼠 ABCG2 的两个独立的药物选择细胞系对荧光底物的外排作用。为此,我们开发并表征了一个新的表达小鼠 Abcg2 的亚系,该亚系显示出已知荧光 ABCG2 底物的外排作用,并对米托蒽醌(在 ABCG2 抑制剂 Ko143 存在下减少)的耐药性增加。我们的结果表明,人源和鼠源 ABCG2 的底物特异性非常相似。我们鉴定了一种新的人源和鼠源 ABCG2 底物,卟啉类似物,紫红素-18(Pp-18),它不是 P-糖蛋白或多药耐药蛋白 1 的底物。使用 Pp-18 评估抑制剂阻断 ABCG2 外排活性的能力。抑制剂对人源和鼠源 ABCG2 也表现出相似的作用。白杨素、苯并黄酮和环孢菌素 A 抑制人源和鼠源 ABCG2 中的 Pp-18 外排。人源和鼠源 ABCG2 的底物和抑制剂特异性相似,支持在理解 ABCG2 的临床、药理学和生理学作用时,将小鼠模型解释为。