miR-106b-5p promotes renal cell carcinoma aggressiveness and stem-cell-like phenotype by activating Wnt/β-catenin signalling

// Jun Lu 1, * , Jin-Huan Wei 1, * , Zi-Hao Feng 1, * , Zhen-Hua Chen 1, * , Yong-Qian Wang 2 , Yong Huang 1 , Yong Fang 1 , Yan-Ping Liang 1 , Jun-Jie Cen 1 , Yi-Hui Pan 1 , Bing Liao 3 , Wen-Fang Chen 3 , Wei Chen 1 , Jun-Hang Luo 1 1 Department of Urology, First Affiliated Hospital, Sun Yat-sen University, Guangdong, China 2 Department of Musculoskeletal Oncology, First Affiliated Hospital, Sun Yat-sen University, Guangdong, China 3 Department of Pathology, First Affiliated Hospital, Sun Yat-sen University, Guangdong, China * These authors contributed equally to this work Correspondence to: Jun-Hang Luo, email: luojunh@mail.sysu.edu.cn Keywords: miR-106b-5p, stemness, Wnt signalling, tumorigenesis, renal cell carcinoma Received: October 29, 2016 Accepted: February 06, 2017 Published: February 21, 2017 ABSTRACT Purpose: To examine the role of miR-106b-5p in regulating the cancer stem-cell-like phenotype in clear cell renal cell carcinomas (ccRCC). Experimental Design: Real-time PCR was performed to evaluate miR-106b-5p levels in ccRCC cell lines and patients specimens. A series of in vivo and in vitro assays were performed to confirm the effect of miR-106b-5p on ccRCC stemness phenotype. Results: ccRCC cells and tissues expressed more miR-106b-5p than normal controls. Gain- and loss-of-function studies demonstrated that overexpression of miR-106b-5p in ccRCC cells increased the spheres formation ability and the proportion of side population cells. Ectopic expression of miR-106b-5p in ccRCC cells increased tumour growth rates and the number of metastatic colonies in the lungs by using an orthotopic kidney cancer model and a tail vein injection model, respectively. Mechanistic studies revealed that, miR-106b-5p has an activating effect on Wnt/β-catenin signalling. miR-106p-5p overexpression simultaneously targets multiple negative regulators of the Wnt/β-catenin pathway, namely, LZTFL1, SFRP1 and DKK2. In addition, we also confirmed that miR-106b-5p and its targets expression correlates with the overall-survival of ccRCC patients from TCGA. Conclusions: These findings suggest that miR-106b-5p mediates the constitutive activation of Wnt/β-catenin signalling, likely serving as a potential therapeutic target for ccRCC.