Falkenberg Natalie, Anastasov Nataša, Schaub Annalisa, Radulovic Vanja, Schmitt Manfred, Magdolen Viktor, Aubele Michaela
Institute of Pathology, German Research Center for Environmental Health, Neuherberg, Germany.
Institute of Radiation Biology, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany.
Oncotarget. 2015 Apr 10;6(10):8103-14. doi: 10.18632/oncotarget.3516.
miR-221/-222 and components of the urokinase-type plasminogen activator system (uPAS) are associated with metastasis and poor prognosis in breast cancer, including the triple-negative subtype (TNBC). Modification of components of uPAS and involved miRNAs may contribute to targeted therapy for breast cancer patients. miR-221-/-222-overexpressing or miR-221-depleted cells were employed for qRT-PCR and Western blots to show associations of uPAR with miR-221/-222. To substantiate direct targeting of miR-221/-222 within 3' UTR of the uPAR isoform 2, in silico analysesand in vitro assays were conducted. Significant associations between miR-221 and uPAR isoform 2 expressions were observed at the mRNA and protein levels in breast cancer cells representing TNBC. For the first time, the uPAR isoform 2 was demonstrated as direct target for miR-221/-222. Inhibition of miR-221 reduced uPAR protein expression and expression of the tumor cell invasion markers vimentin and RHOC. These results demonstrate a direct and positive regulation of the secreted uPAR isoform 2 by miR-221, increasing its protein expression, a prerequisite for malignancy, while the other uPAR isoforms (1, 3 and 4) are indirectly regulated through miR-10b and miR-221/-222. By targeting uPAR isoforms and/or miRNA-221/-222, the diagnosis and therapy of breast cancer, in particular in TNBC, could be significantly improved.
微小RNA-221/-222与尿激酶型纤溶酶原激活系统（uPAS）的组分与乳腺癌转移及预后不良相关，包括三阴性亚型（TNBC）。对uPAS组分及相关微小RNA进行修饰可能有助于乳腺癌患者的靶向治疗。采用过表达微小RNA-221/-222或缺失微小RNA-221的细胞进行定量逆转录聚合酶链反应（qRT-PCR）和蛋白质免疫印迹，以显示尿激酶型纤溶酶原激活物受体（uPAR）与微小RNA-221/-222的关联。为证实微小RNA-221/-222对uPAR同工型2的3'非翻译区（UTR）的直接靶向作用，进行了计算机分析和体外试验。在代表TNBC的乳腺癌细胞的mRNA和蛋白质水平上，观察到微小RNA-221与uPAR同工型2表达之间存在显著关联。首次证明uPAR同工型2是微小RNA-221/-222的直接靶点。抑制微小RNA-221可降低uPAR蛋白表达以及肿瘤细胞侵袭标志物波形蛋白和RhoC的表达。这些结果表明，微小RNA-221对分泌型uPAR同工型2具有直接的正向调节作用，增加其蛋白表达，这是恶性肿瘤的一个先决条件，而其他uPAR同工型（1、3和4）则通过微小RNA-10b和微小RNA-221/-222受到间接调节。通过靶向uPAR同工型和/或微小RNA-221/-222，可显著改善乳腺癌尤其是TNBC的诊断和治疗。
