Department of Chemical and Material Engineering, Faculty of Engineering, University of Alberta, Edmonton, Alberta, Canada.
Cancer Gene Ther. 2013 Mar;20(3):169-77. doi: 10.1038/cgt.2013.8. Epub 2013 Mar 1.
Enhanced survival mechanisms of malignant cells in combination with elevated levels of drug transporters can sustain an undesirable resistance against drug therapy. Short interfering RNA (siRNA) delivery against targets involved in aberrant mechanisms is a promising approach and we hypothesize that simultaneous silencing of multiple targets could prove more advantageous than common approach to silence individual targets. To explore this approach, we targeted anti-apoptotic proteins myeloid cell leukemia 1 (Mcl-1) and survivin along with the efflux pump P-glycoprotein (P-gp) in drug-resistant breast cancer cells. Polymeric siRNA delivery was employed for this purpose by using small polyethylenimine (PEI) substituted with lipids. While silencing Mcl-1 caused ∼90% cell death in wild-type cells, this effect was less significant in P-gp over-expressing cells. An additive effect for Mcl-1 and P-gp silencing was evident in the latter cells, where simultaneous silencing of these targets created a significantly higher effect compared with silencing each individual target. Prolonged exposure of wild-type cells to doxorubicin (DOX) resulted in upregulation of P-gp, breast cancer resistance protein, survivin and Mcl-1. Dual silencing of P-gp and Mcl-1 again resulted in an additive effect in resistance-induced cells, which displayed an increased dependency on Mcl-1 for survival. Cytotoxic effect of DOX was also enhanced in resistance-induced cells after silencing Mcl-1. We conclude that polymer-mediated siRNA delivery can silence multiple targets simultaneously and reverse drug resistance.
恶性细胞增强的生存机制与药物转运体水平升高相结合，可以维持对药物治疗的不良耐药性。针对异常机制相关靶点的短干扰 RNA（siRNA）递送是一种很有前途的方法，我们假设同时沉默多个靶点可能比单独针对单个靶点的常见方法更有利。为了探索这种方法，我们针对耐药乳腺癌细胞中的抗凋亡蛋白髓样细胞白血病 1（Mcl-1）和生存素以及外排泵 P-糖蛋白（P-gp）。为此，我们使用带有脂质的小聚乙烯亚胺（PEI）来进行聚合物 siRNA 递送。虽然沉默 Mcl-1 会导致野生型细胞约 90%的细胞死亡，但在 P-gp 过表达的细胞中这种效果不那么明显。在后者的细胞中，Mcl-1 和 P-gp 沉默的协同作用是明显的，同时沉默这些靶点会产生比单独沉默每个靶点更高的效果。野生型细胞长时间暴露于阿霉素（DOX）会导致 P-gp、乳腺癌耐药蛋白、生存素和 Mcl-1 的上调。在耐药诱导的细胞中，P-gp 和 Mcl-1 的双重沉默再次产生协同作用，这些细胞对 Mcl-1 的生存依赖性增加。沉默 Mcl-1 后，耐药诱导细胞中 DOX 的细胞毒性作用也增强。我们得出结论，聚合物介导的 siRNA 递送可以同时沉默多个靶点并逆转耐药性。
