Inhibition of the PI3K-Akt signaling pathway disrupts ABCG2-rich extracellular vesicles and overcomes multidrug resistance in breast cancer cells
Inhibition of the PI3K-Akt signaling pathway disrupts ABCG2-rich extracellular vesicles and overcomes multidrug resistance in breast cancer cells
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DOI：
10.1016/j.bcp.2012.01.033
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发表时间：
2012-05-15
影响因子：
5.8
通讯作者：
Assaraf, Yehuda G.
中科院分区：
文献类型：
--
作者：
Goler-Baron, Vicky;Sladkevich, Irina;Assaraf, Yehuda G.
我们最近发现，富含ABCG 2的细胞外囊泡（EV）在相邻的乳腺癌细胞之间形成，并积极集中各种化疗药物，导致多药耐药（MDR）。在这里，我们研究了调节ABCG 2靶向EV的信号通路，因为其抑制将克服MDR。PI 3 K-Akt信号通路可能与ABCG 2的亚细胞定位有关;因此，我们在此表明，Akt信号的药理学抑制导致ABCG 2从EV膜逐渐重新定位到细胞质。包括β-肌动蛋白和紧密连接蛋白ZO-1在内的细胞骨架标志物，沿着EV标志物ABCG 2和Ezrin-Radixin-Moesin揭示了这种细胞内ABCG 2保留导致EV大小和数量的逐渐减少，导致EV消除和MDR的完全逆转。Akt信号的抑制恢复了药物对米托蒽醌和托泊替康（真正的ABCG 2转运底物）的敏感性，因此相当于ABCG 2转运抑制剂Ko 143实现的MDR逆转。值得注意的是，除了ABCG 2转运活性的丧失，用Ko 143处理MCF-7/MR细胞导致ABCG 2的细胞质重定位，类似于Akt抑制后观察到的表型。我们的结论是PI 3 K-Akt信号通路是ABCG 2亚细胞定位、EV生物发生和功能性MDR的关键调节因子。此外，ABCG 2的正确折叠及其靶向EV膜是EV生物发生及其MDR功能的关键组成部分。我们提出，破坏ABCG 2靶向和EV生物发生的Akt信号传导抑制剂可以容易地克服MDR，从而用这些有前途的药物组合进行体内研究。(C)2012 Elsevier Inc. All rights reserved.
We have recently shown that ABCG2-rich extracellular vesicles (EVs) form between neighbor breast cancer cells and actively concentrate various chemotherapeutics, resulting in multidrug resistance (MDR). Here we studied the signaling pathway regulating ABCG2 targeting to EVs as its inhibition would overcome MDR. The PI3K-Akt signaling pathway was possibly implicated in subcellular localization of ABCG2; we accordingly show here that pharmacological inhibition of Akt signaling results in gradual relocalization of ABCG2 from the EVs membrane to the cytoplasm. Cytoskeletal markers including beta-actin and the tight junction protein ZO-1, along with the EVs markers ABCG2 and Ezrin-Radixin-Moesin revealed that this intracellular ABCG2 retention leads to gradual decrease in the size and number of EVs, resulting in EVs elimination and complete reversal of MDR. Inhibition of Akt signaling restored drug sensitivity to mitoxantrone and topotecan, bona fide ABCG2 transport substrates, hence being equivalent to MDR reversal achieved with the ABCG2 transport inhibitor Ko143. Remarkably, apart from loss of ABCG2 transport activity, treatment of MCF-7/MR cells with Ko143 resulted in cytoplasmic relocalization of ABCG2, similarly to the phenotype observed after Akt inhibition. We conclude that the PI3K-Akt signaling pathway is a key regulator of subcellular localization of ABCG2, EVs biogenesis and functional MDR. Furthermore, proper folding of ABCG2 and its targeting to the EVs membrane are crucial components of the biogenesis of EVs and their MDR function. We propose that Akt signaling inhibitors which disrupt ABCG2 targeting and EVs biogenesis may readily overcome MDR thus warranting in vivo studies with these promising drug combinations. (C) 2012 Elsevier Inc. All rights reserved.