Abstract
miRNAs are implicated in regulating cancer progression and metastasis. Here, we show that miR-720 is positively associated with renal cell carcinoma (RCC). Elevated levels of miR-720 were observed in a panel of RCC cell lines and clinical tissues compared with nonmalignant cell line and normal samples. Loss of miR-720 function inhibited proliferation, migration, and invasion and induced apoptosis in RCC cell lines in vitro and repressed tumor growth in xenograft mouse models. Conversely, gain of miR-720 function in nonmalignant HK-2 cells induced procancerous characteristics. Silencing of miR-720 caused a marked induction in the levels of endogenous αE-catenin and E-cadherin protein levels in anti720 transfected cells compared with control, whereas miR-720 overexpression in RCC cell lines reduced activity of a luciferase reporter gene fused to the wild-type αE-catenin or E-cadherin 3'UTR compared with nonspecific 3'UTR control, indicating that αE-catenin-E-cadherin complex is a direct and functional target of miR-720 in RCC. We also observed attenuation of β-catenin, CD44, and Akt expression in RCC cells transfected with miR-720 inhibitor compared with control. Furthermore, miR-720 exhibited clinical significance in RCC. Expression of miR-720 significantly distinguished malignant from normal samples. Elevated miR-720 levels positively correlated with higher Fuhrman grade, pathologic stage, and poor overall survival of RCC patients. These findings uncover a new regulatory network in RCC involving metastasis-promoting miR-720 that directly targets expression of key metastasis-suppressing proteins E-cadherin and αE-catenin complex. These results suggest that therapeutic regulation of miR-720 may provide an opportunity to regulate EMT and metastasis in RCC. Mol Cancer Ther; 16(12); 2840-8. ©2017 AACR.