Department of Laboratory Medicine and the Keenan Research Centre, Li Ka Shing Knowledge Institute of St. Michael's Hospital, 30 Bond Street, Toronto, Ontario M5B 1W8, Canada.
Carcinogenesis. 2013 Oct;34(10):2231-9. doi: 10.1093/carcin/bgt184. Epub 2013 May 28.
MicroRNAs (miRNAs) play a crucial role in tumor progression and metastasis. We, and others, recently identified a number of miRNAs that are dysregulated in metastatic renal cell carcinoma compared with primary renal cell carcinoma. Here, we investigated three miRNAs that are significantly downregulated in metastatic tumors: miR-192, miR-194 and miR-215. Gain-of-function analyses showed that restoration of their expression decreases cell migration and invasion in renal cell carcinoma cell line models, whereas knockdown of these miRNAs resulted in enhancing cellular migration and invasion abilities. We identified three targets of these miRNAs with potential role in tumor aggressiveness: murine double minute 2, thymidylate synthase, and Smad Interacting protein 1/zinc finger E-box binding homeobox 2. We observed a convergent effect (the same molecule can be targeted by all three miRNAs) and a divergent effect (the same miRNA can control multiple targets) for these miRNAs. We experimentally validated these miRNA-target interactions using three independent approaches. First, we observed that miRNA overexpression significantly reduces the mRNA and protein levels of their targets. In the second, we observed significant reduction of the luciferase signal of a vector containing the 3'UTR of the target upon miRNA overexpression. Finally, we show the presence of inverse correlation between miRNA changes and the expression levels of their targets in patient specimens. We also examined the prognostic significance of miR-215 in renal cell carcinoma. Lower expression of miR-215 is associated with significantly reduced disease-free survival time. These findings were validated on an independent data set from The Cancer Genome Atlas. These results can pave the way to the clinical use of miRNAs as prognostic markers and therapeutic targets.
微小 RNA（miRNAs）在肿瘤的发生和转移中起着至关重要的作用。我们和其他人最近发现，与原发性肾细胞癌相比，转移性肾细胞癌中有许多 miRNAs 表达失调。在这里，我们研究了三种在转移性肿瘤中明显下调的 miRNAs：miR-192、miR-194 和 miR-215。功能获得分析表明，恢复它们的表达会降低肾细胞癌细胞系模型中的细胞迁移和侵袭，而敲低这些 miRNAs 则会增强细胞迁移和侵袭能力。我们鉴定了这些 miRNAs 的三个靶标，它们在肿瘤侵袭性中具有潜在作用：鼠双微体 2、胸苷酸合成酶和 Smad 相互作用蛋白 1/锌指 E 框结合同源盒 2。我们观察到这些 miRNAs 的趋同效应（同一个分子可以被所有三个 miRNAs 靶向）和发散效应（同一个 miRNA 可以控制多个靶标）。我们使用三种独立的方法验证了这些 miRNA-靶标相互作用。首先，我们观察到 miRNA 的过表达显著降低了其靶标的 mRNA 和蛋白水平。其次，我们观察到在 miRNA 过表达时，包含靶标 3'UTR 的载体的荧光素酶信号显著降低。最后，我们表明在患者标本中 miRNA 变化与靶标表达水平之间存在反比关系。我们还检查了 miR-215 在肾细胞癌中的预后意义。miR-215 的低表达与疾病无进展生存时间明显缩短相关。这些发现得到了来自癌症基因组图谱的独立数据集的验证。这些结果为 miRNA 作为预后标志物和治疗靶点的临床应用铺平了道路。
