P-Glycoprotein-mediated resistance to Hsp90-directed therapy is eclipsed by the heat shock response.
P-Glycoprotein-mediated resistance to Hsp90-directed therapy is eclipsed by the heat shock response.
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DOI：
10.1158/0008-5472.can-07-5175
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发表时间：
2008-09-15
期刊：
影响因子：
11.2
通讯作者：
Erlichman C
中科院分区：
文献类型：
--
作者：
McCollum AK;TenEyck CJ;Stensgard B;Morlan BW;Ballman KV;Jenkins RB;Toft DO;Erlichman C
尽管研究证明了 Hsp90 抑制剂（例如格尔德霉素 (GA) 及其衍生物 17-烯丙氨基-去甲氧基格尔德霉素 (17-AAG)）的抗肿瘤活性，但最近的报告表明这些抑制剂缺乏显着的单药临床活性。对 Hsp90 抑制剂的耐药性先前已被认为与 P-糖蛋白 (P-gp) 的表达和多重耐药 (MDR) 表型有关。然而，GA 治疗引起的应激反应也会导致对 Hsp90 靶向治疗的耐药性。因此，我们选择进一步研究 P-gp 和应激反应在 17-AAG 抗性中的相对重要性。集落形成测定表明，与亲代细胞相比，P-gp 的高表达可使转染 P-gp 的细胞中的 17-AAG IC50 增加 6 倍。选择对 GA 产生耐药性的 A549 细胞过表达 P-gp，但维拉帕米 (VP) 并未逆转这种耐药性。这些细胞还过度表达 Hsp27，并用 17-AAG 处理诱导 Hsp70。当用Hsp27和/或Hsp70 siRNA转染GA和17-AAG抗性细胞时，与对照转染细胞相比，17-AAG IC50降低10倍。用针对 Hsp27、Hsp70 或 Hsp27 和 Hsp70 的 siRNA 转染也增加了对 EC78 的敏感性，EC78 是一种基于嘌呤支架的 Hsp90 抑制剂，不是 P-gp 底物。我们得出的结论是，P-gp 可能在一定程度上有助于抵抗 17-AAG，但通过 Hsp90 靶向治疗诱导应激反应蛋白（如 Hsp27 和 Hsp70）发挥着更大的作用。综上所述，我们的结果表明，应利用 Hsp27 和 Hsp70 为靶点来提高 Hsp90 导向疗法的临床疗效。
Despite studies that demonstrate the antitumor activity of Hsp90 inhibitors such as geldanamycin (GA) and its derivative 17-allylamino-demethoxygeldanamycin (17-AAG), recent reports indicate that these inhibitors lack significant single-agent clinical activity. Resistance to Hsp90 inhibitors has been previously linked to expression of P-glycoprotein (P-gp), and the multidrug resistant (MDR) phenotype. However, the stress response induced by GA treatment can also cause resistance to Hsp90-targeted therapy. Therefore we chose to further investigate the relative importance of P-gp and the stress response in 17-AAG resistance. Colony forming assays revealed that high expression of P-gp could increase the 17-AAG IC50 6-fold in cells transfected with P-gp as compared with parent cells. A549 cells selected for resistance to GA overexpressed P-gp, but verapamil (VP) did not reverse the resistance. These cells also overexpressed Hsp27, and Hsp70 was induced with 17-AAG treatment. When the GA and 17-AAG resistant cells were transfected with Hsp27 and/or Hsp70 siRNA, the 17-AAG IC50 decreased 10-fold compared to control transfected cells. Transfection with siRNA directed against Hsp27, Hsp70, or Hsp27 and Hsp70 also increased sensitivity to EC78, a purine scaffold-based Hsp90 inhibitor that is not a P-gp substrate. We conclude that P-gp may contribute, in part, to resistance to 17-AAG, but induction of stress response proteins such as Hsp27 and Hsp70 by Hsp90-targeted therapy plays a larger role. Taken together, our results indicate that targeting of Hsp27 and Hsp70 should be exploited to increase the clinical efficacy of Hsp90-directed therapy.