Downregulation of eIF4G by microRNA-503 enhances drug sensitivity of MCF-7/ADR cells through suppressing the expression of ABC transport proteins.
Downregulation of eIF4G by microRNA-503 enhances drug sensitivity of MCF-7/ADR cells through suppressing the expression of ABC transport proteins.
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microRNA-503 下调 eIF4G 通过抑制 ABC 转运蛋白的表达增强 MCF-7/ADR 细胞的药物敏感性
DOI：
10.3892/ol.2017.6049
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发表时间：
2017-06
期刊：
影响因子：
2.9
通讯作者：
Lei X
中科院分区：
文献类型：
--
作者：
Pan X;Yang X;Zang J;Zhang S;Huang N;Guan X;Zhang J;Wang Z;Li X;Lei X
三磷酸腺苷结合盒（ABC）转运蛋白的过表达正在成为抗癌药物耐药性的关键因素。真核生物翻译起始因子（eIF）4F复合物是mRNA翻译的关键调控因子，在肿瘤耐药中受磷酸肌醇3-激酶-AKT-哺乳动物雷帕霉素靶蛋白通路的调控。本研究证实了ABC翻译蛋白改变在MCF-7人乳腺细胞获得阿霉素（ADM）耐药表型中的作用。分别采用定量聚合酶链反应和蛋白质印迹分析来检测mRNA和蛋白质水平的差异。结果发现，在MCF-7/ADR细胞中，ABC亚家族B成员1、ABC亚家族C成员1和ABC亚家族G成员2转运蛋白的表达上调。MTT法检测MCF-7/ADR细胞对阿霉素（ADM）、三苯氧胺（TAM）和紫杉醇（TAX）的敏感性。我们通过计算程序预测真核生物翻译起始因子4-γ 1（eIF 4G）的3′-非翻译区可能含有microRNA（miR）-503的结合位点。这些结合位点通过荧光素酶报告基因测定来证实。在用miR-503模拟物转染的细胞中，eIF 4G mRNA降解加速。此外，证明了在用miR-503转染后，MCF-7/ADR细胞中eIF 4G和ABC翻译蛋白显著下调。发现miR-503模拟物可以使细胞对ADM、TAM和TAX处理敏感。这些发现首次证明eIF 4G在MCF-7/ADR细胞中起关键作用，并可能是预防和逆转乳腺癌多药耐药的有效药物。
Overexpression of adenosine triphosphate-binding cassette (ABC) transport protein is emerging as a critical contributor to anticancer drug resistance. The eukaryotic translation initiation factor (eIF) 4F complex, the key modulator of mRNA translation, is regulated by the phosphoinositide 3-kinase-AKT-mammalian target of rapamycin pathway in anticancer drug-resistant tumors. The present study demonstrated the roles of ABC translation protein alterations in the acquisition of the Adriamycin (ADM)-resistant phenotype of MCF-7 human breast cells. Quantitative polymerase chain reaction and western blot analysis were applied to examine the differences in mRNA and protein levels, respectively. It was found that the expression of the ABC sub-family B member 1, ABC sub-family C member 1 and ABC sub-family G member 2 transport proteins were upregulated in MCF-7/ADR cells. An MTT assay was used to detect the cell viability, from the results MCF-7/ADR cells were less sensitive to ADM, tamoxifen (TAM) and taxol (TAX) treatment compared with MCF-7 cells. We predicted that the 3′-untranslated region of eukaryotic translation initiation factor 4-γ 1 (eIF4G) contains a potential miRNA binding site for microRNA (miR)-503 through using computational programs. These binding sites were confirmed by luciferase reporter assays. eIF4G mRNA degradation was accelerated in cells transfected with miR-503 mimics. Furthermore, it was demonstrated that eIF4G and ABC translation proteins were significantly downregulated in MCF-7/ADR cells after transfection with miR-503. It was found that miR-503 mimics could sensitize the cells to treatment with ADM, TAM and TAX. These findings demonstrated for the first time that eIF4G acted as a key factor in MCF-7/ADR cells, and may be an efficient agent for preventing and reversing multi-drug resistance in breast cancer.