Bivalent probes of the human multidrug transporter P-glycoprotein
Bivalent probes of the human multidrug transporter P-glycoprotein
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DOI：
10.1021/bi0608109
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发表时间：
2006-09-26
期刊：
影响因子：
2.9
通讯作者：
Chmielewski, Jean
中科院分区：
文献类型：
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作者：
Pires, Marcos M.;Hrycyna, Christine A.;Chmielewski, Jean
设计了一个小的二价试剂库，用于探测人多药转运蛋白P-糖蛋白（P-gp）的底物结合位点。二价试剂由两个拷贝的P-gp底物embryos组成，通过不同组成的系链连接。发现大约10埃的发射分子之间的最佳距离对于阻挡已知荧光底物罗丹明123的传输是必要的。此外，确定疏水系链对于桥接二价化合物是最佳的;系链内的亲水或阳离子部分对转运抑制具有不利影响。除了作为P-gp药物结合位点的探针外，这些药物也是P-gp的有效抑制剂。一种药物EmeC 5抑制罗丹明123转运的IC 50值为2.9 μ M，抑制已知P-gp底物[I-125]-碘芳基叠氮吡唑嗪结合的IC 50值约为5 nM。虽然EmeC 5是P-gp的抑制剂，并显示直接与P-gp在一个或多个底物结合位点相互作用，我们的数据表明，它不是P-gp转运底物本身或穷人。最重要的是，当与细胞毒性剂如阿霉素共同给药时，EmeC 5显示出逆转MCF-7/DX 1细胞的MDR表型。
A small library of bivalent agents was designed to probe the substrate binding sites of the human multidrug transporter P-glycoprotein (P-gp). The bivalent agents were composed of two copies of the P-gp substrate emetine, linked by tethers of varied composition. An optimum distance between the emetine molecules of approximately 10 angstrom was found to be necessary for blocking transport of the known fluorescent substrate rhodamine 123. Additionally, it was determined that hydrophobic tethers were optimal for bridging the bivalent compounds; hydrophilic or cationic moieties within the tether had a detrimental effect on inhibition of transport. In addition to acting as probes of P-gp's drug binding sites, these agents were also potent inhibitors of P-gp. One agent, EmeC5, had IC50 values of 2.9 mu M for inhibiting transport of rhodamine 123 and approximately 5 nM for inhibiting the binding of a known P-gp substrate, [I-125]-iodoarylazidoprazosin. Although EmeC5 is an inhibitor of P-gp and was shown to interact directly with P-gp in one or more of the substrate binding sites, our data suggest that it is either not a P-gp transport substrate itself or a poor one. Most significantly, EmeC5 was shown to reverse the MDR phenotype of MCF-7/DX1 cells when co-administered with a cytotoxic agent, such as doxorubicin.