In vitro and in vivo reversal of P-glycoprotein-mediated multidrug resistance by a novel potent modulator, XR9576.
In vitro and in vivo reversal of P-glycoprotein-mediated multidrug resistance by a novel potent modulator, XR9576.
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发表时间：
2001
期刊：
影响因子：
11.2
通讯作者：
P. Mistry;A. Stewart;Wendy Dangerfield;S. Okiji;C. Liddle;D. Bootle;J. Plumb;D. Templeton;P. Charlton
中科院分区：
文献类型：
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作者：
P. Mistry;A. Stewart;Wendy Dangerfield;S. Okiji;C. Liddle;D. Bootle;J. Plumb;D. Templeton;P. Charlton
肿瘤细胞表面P-糖蛋白（P-gp）的过度表达可导致肿瘤细胞产生多药耐药（MDR）。这种蛋白质作为能量依赖性药物外排泵，降低结构无关药物的细胞内浓度。P-gp功能调节剂可以恢复MDR细胞对此类药物的敏感性。XR 9576是一种新型的邻氨基苯甲酸衍生物，开发为P-gp的有效和特异性抑制剂，在本研究中，我们评估了该化合物的体外和体内调节活性。使用一组人（H69/LX4，2780AD）和鼠（EMT6 AR1.0，MC26）MDR细胞系评价XR 9576的体外活性。XR 9576增强了多柔比星、紫杉醇、依托泊苷和长春新碱等几种药物的细胞毒性;在25 - 80 nM XR 9576存在下实现了完全逆转耐药性。与其他调节剂的直接比较研究表明，XR 9576是迄今为止描述的最有效的调节剂之一。P-gp底物[3H]柔红霉素和罗丹明123的蓄积和外排研究表明，XR 9576可抑制P-gp介导的药物外排。P-gp功能的抑制是可逆的，但从孵育培养基中去除调节剂后，该作用持续> 22小时。这与P-gp底物（如环孢菌素A和维拉帕米）相反，后者在60分钟内失去活性，表明XR 9576不由P-gp转运。此外，XR 9576是[3H]叠氮平对P-gp光亲和标记的强效抑制剂，这意味着与蛋白质直接相互作用。在携带固有耐药MC26结肠肿瘤的小鼠中，同时给予XR 9576可增强多柔比星的抗肿瘤活性，而毒性无显著增加;在2.5 - 4.0 mg/kg剂量下观察到最大增强作用，无论是i.v.还是p.o.此外，共施用XR 9576（6 - 12 mg/kg p.o.）完全恢复紫杉醇、依托泊苷和长春新碱对两种高度耐药的人肿瘤异种移植物（2780AD，H69/LX4）在裸鼠中的抗肿瘤活性。重要的是，所有有效的组合方案似乎耐受良好。此外，静脉内同时给予XR 9576不会改变紫杉醇的血浆药代动力学。这些结果表明，XR 9576是一种非常强效、选择性和有效的调节剂，作用持续时间长。它的静脉注射和口服都很有效。活性而不明显增强紫杉醇的血浆药代动力学或联合给药药物的毒性。因此，XR9576在治疗P-gp介导的MDR癌症方面具有很大的前景。
The overexpression of P-glycoprotein (P-gp) on the surface of tumor cells causes multidrug resistance (MDR). This protein acts as an energy-dependent drug efflux pump reducing the intracellular concentration of structurally unrelated drugs. Modulators of P-gp function can restore the sensitivity of MDR cells to such drugs. XR9576 is a novel anthranilic acid derivative developed as a potent and specific inhibitor of P-gp, and in this study we evaluate the in vitro and in vivo modulatory activity of this compound. The in vitro activity of XR9576 was evaluated using a panel of human (H69/LX4, 2780AD) and murine (EMT6 AR1.0, MC26) MDR cell lines. XR9576 potentiated the cytotoxicity of several drugs including doxorubicin, paclitaxel, etoposide, and vincristine; complete reversal of resistance was achieved in the presence of 25-80 nM XR9576. Direct comparative studies with other modulators indicated that XR9576 was one of the most potent modulators described to date. Accumulation and efflux studies with the P-gp substrates, [3H]daunorubicin and rhodamine 123, demonstrated that XR9576 inhibited P-gp-mediated drug efflux. The inhibition of P-gp function was reversible, but the effects persisted for >22 h after removal of the modulator from the incubation medium. This is in contrast to P-gp substrates such as cyclosporin A and verapamil, which lose their activity within 60 min, suggesting that XR9576 is not transported by P-gp. Also, XR9576 was a potent inhibitor of photoaffinity labeling of P-gp by [3H]azidopine implying a direct interaction with the protein. In mice bearing the intrinsically resistant MC26 colon tumors, coadministration of XR9576 potentiated the antitumor activity of doxorubicin without a significant increase in toxicity; maximum potentiation was observed at 2.5-4.0 mg/kg dosed either i.v. or p.o. In addition, coadministration of XR9576 (6-12 mg/kg p.o.) fully restored the antitumor activity of paclitaxel, etoposide, and vincristine against two highly resistant MDR human tumor xenografts (2780AD, H69/LX4) in nude mice. Importantly all of the efficacious combination schedules appeared to be well tolerated. Furthermore, i.v. coadministration of XR9576 did not alter the plasma pharmacokinetics of paclitaxel. These results demonstrate that XR9576 is an extremely potent, selective, and effective modulator with a long duration of action. It exhibits potent i.v. and p.o. activity without apparently enhancing the plasma pharmacokinetics of paclitaxel or the toxicity of coadministered drugs. Hence, XR9576 holds great promise for the treatment of P-gp-mediated MDR cancers.