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.
385 Background: miRNAs play a crucial rule in tumor progression and metastasis. We previously identified miR-192, miR-194 and miR-215 to be down-regulated in metastatic compared to primary clear cell renal cell carcinoma (ccRCC). In this work, we examine the role of miR-192, miR-194, and miR-215 in RCC progression and aggressiveness. Methods: We examined the role of these three miRNAs on tumor cell migration and invasion abilities using RCC cell line models. We performed target prediction analysis and experimentally validated the targets using independent approaches. In addition, we examined the clinical utility of miR-215 as a potential prognostic marker in RCC by measuring miR-215 expression using qRT-PCR in 61 formalin-fixed paraffin-embedded tissues from primary ccRCC and correlated the expression levels with clinical outcome. Results: Restoration of miR-192, miR-194, and miR-215 expression decreased cell migration and invasion in RCC cell lines. Target prediction analysis identified three potential targets of these miRNAs; MDM2, TYMS, and SIP1/ZEB2. We validated the miRNA-target interaction experimentally using three approaches. First by measuring the effect of miRNA overexpression on mRNA and protein levels of the predicted target, then by measuring the effect of miRNA overexpression on a luciferase signal of a vector containing the 3’UTR of the predicted target, and finally, by validating these interactions in vivoby examining the presence of an inverse correlation between miRNA changes and the expression levels of their targets on clinical specimens. In 61 patients with resected ccRCC tumors, we found that low miR-215 expression in the primary was associated with a significantly reduced recurrence-free survival. (26.4 vs. 49.2 months, respectively, p = 0.0320). Conclusions: Our analysis showed that miR-192, miR-194, and miR-215 are involved in RCC metastasis and that miR-215 predicts for recurrence in patients with resected RCC. Our findings pave the way to the clinical use of miRNAs as prognostic markers and potential therapeutic targets.
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