The molecular interaction of the high affinity reversal agent XR9576 with P-glycoprotein
The molecular interaction of the high affinity reversal agent XR9576 with P-glycoprotein
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DOI：
10.1038/sj.bjp.0702807
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发表时间：
1999-09-01
影响因子：
7.3
通讯作者：
Callaghan, R
中科院分区：
文献类型：
--
作者：
Martin, C;Berridge, G;Callaghan, R
1 平衡结合的动力学和性质用于表征邻氨基苯甲酸衍生物 [H-3]-XR9576 与多药耐药性 P-糖蛋白 (P-gp) 的分子相互作用。 XR9576 显示出与 P-gp 的特异性高亲和力结合（B-max=275 pmol mg(-1)，K-d=5.1 nM）。转运底物[H-3]-长春花碱和[H-3]-紫杉醇对P-gp的亲和力分别低4倍和20倍。与长春碱相比，XR9576 与 P-gp 的作用持续时间更长，长春碱表现出较慢的缔合速率和较快的解离速率。2 通过置换药物平衡结合测定确定了几种调节剂和转运底物与 P-gp 相互作用的相对亲和力。长春碱和紫杉醇只能部分取代 [H-3]-XR9576 结合，显示出的 K-i 值与其测量的 K-d 值显着不同。这表明 XR9576 与 P-gp 底物长春碱和紫杉醇之间存在非竞争性相互作用。3 XR9576 被证明是 P-gp 介导的 [H-3]-长春碱和 [H-3]-紫杉醇转运的有效调节剂，因为它使 CH(r)B30 细胞中这些细胞毒素的稳态积累增加到在非 P-gp 表达中观察到的水平AuxB1 细胞 (EC50= 487+/-50 nM)。这种药物转运的抑制不是通过转运竞争介导的，因为 [H-3]-XR9576 积累不受 P-gp 表达或功能的影响。 4 这些结果表明，与任何其他报道的调节剂相比，P-gp 调节剂 XR9576 表现出更高的选择性、抑制持续时间以及与该转运蛋白的相互作用效力。多项证据表明，XR9576 通过在不同于转运底物相互作用位点的位点结合来抑制 P-gp 功能。这两个站点可被分类为提供调制或传输功能。
1 The kinetics and nature of equilibrium binding were used to characterize the molecular interaction of the anthranilic acid derivative [H-3]-XR9576 with the multidrug resistance P-glycoprotein (P-gp). XR9576 displayed specific high-affinity binding to P-gp (B-max=275 pmol mg(-1), K-d=5.1 nM). The transport substrates [H-3]-vinblastine and [H-3]-paclitaxel displayed 4 fold and 20 fold lower affinity respectively for P-gp. The duration of action of XR9576 with P-gp was increased in comparison to that of vinblastine which displayed a slower rate of association and a faster dissociation rate.2 The relative affinities of several modulators and transport substrates to interact with P-gp were determined from displacement drug equilibrium binding assays. Vinblastine and paclitaxel could only fractionally displace [H-3]-XR9576 binding, displaying K-i values significantly different from their measured K-d values. This suggests a non-competitive interaction between XR9576 and the P-gp substrates vinblastine and paclitaxel.3 XR9576 was shown to be a potent modulator of P-gp mediated [H-3]-vinblastine and [H-3]- paclitaxel transport as it increased the steady-state accumulation of these cytotoxics in CH(r)B30 cells to levels observed in non-P-gp-expressing AuxB1 cells (EC50= 487+/-50 nM). This inhibition of drug transport is not mediated through competition for transport since [H-3]-XR9576 accumulation was not influenced by P-gp expression or function.4 These results demonstrate that the P-gp modulator XR9576 exhibits greater selectivity, duration of inhibition and potency of interaction with this transporter than any other reported modulators. Several lines of evidence suggest that XR9576 inhibits P-gp function by binding at a site which is distinct from the site of interaction of transport substrates. The two sites may be classified as serving modulatory or transport functions.