Tianqi Lin1, Yun Yang2, Xiaohong Ye2, Jiayue Yao2, Hu Zhou2. 1. Department of Urology, Zhangzhou Affiliated Hospital of Fujian Medical University Zhangzhou, Fujian, China. 2. School of Pharmaceutical Sciences, Fujian Provincial Key Laboratory of Innovative Drug Target Research, High Throughput Drug Screening Platform, Xiamen University Xiamen, Fujian, China.
Abstract
OBJECTIVE: Dysfunctions of microRNAs have been implicated in the progression of clear cell renal cell carcinoma (ccRCC). Here, we investigated the roles of miR-99b and miR-99b* in ccRCC development. METHODS: The expression levels of miR-99b and miR-99b* in tumor and tumor-adjacent tissues from ccRCC patients were quantified by quantitative Real-Time PCR (qRT-PCR). MicroRNA mimics and inhibitors were employed to evaluate the functions of miR-99b and miR-99b*. The effects of miR-99b on the proliferation and migration of ccRCC cells were analyzed by MTT and wound-healing assays, respectively. The effect of miR-99b on the expression of its target gene IGF1R and mTOR was determined by western blotting and qRT-PCR. RESULTS: The abundances of miR-99b and miR-99b* were lower in ccRCC tissues than in the tumor-adjacent tissues from patients. Similarly, the expression of these two microRNAs was higher in the normal kidney HK-2 cells than in the ccRCC cell lines. Moreover, miR-99b and miR-99b* inhibited the proliferation and migration of ccRCC cells. MiR-99b was found to down-regulate IGF1R and mTOR expression, likely through targeting their mRNAs to induce degradation. Consistently, the mRNA levels of IGF1R and mTOR were higher in ccRCC tissues than in the tumor-adjacent tissues, and Akt, a downstream factor of IGF1R, was highly activated correspondingly in ccRCC tissues. CONCLUSION: The low expression of miR-99b and miR-99b* contributes to ccRCC development and miR-99b acts as an onco-suppressor by suppressing IGF1R and mTOR expression to down-regulate IGF1R/AKT/mTOR signaling. IJCEP
OBJECTIVE: Dysfunctions of microRNAs have been implicated in the progression of clear cell renal cell carcinoma (ccRCC). Here, we investigated the roles of miR-99b and miR-99b* in ccRCC development. METHODS: The expression levels of miR-99b and miR-99b* in tumor and tumor-adjacent tissues from ccRCC patients were quantified by quantitative Real-Time PCR (qRT-PCR). MicroRNA mimics and inhibitors were employed to evaluate the functions of miR-99b and miR-99b*. The effects of miR-99b on the proliferation and migration of ccRCC cells were analyzed by MTT and wound-healing assays, respectively. The effect of miR-99b on the expression of its target gene IGF1R and mTOR was determined by western blotting and qRT-PCR. RESULTS: The abundances of miR-99b and miR-99b* were lower in ccRCC tissues than in the tumor-adjacent tissues from patients. Similarly, the expression of these two microRNAs was higher in the normal kidney HK-2 cells than in the ccRCC cell lines. Moreover, miR-99b and miR-99b* inhibited the proliferation and migration of ccRCC cells. MiR-99b was found to down-regulate IGF1R and mTOR expression, likely through targeting their mRNAs to induce degradation. Consistently, the mRNA levels of IGF1R and mTOR were higher in ccRCC tissues than in the tumor-adjacent tissues, and Akt, a downstream factor of IGF1R, was highly activated correspondingly in ccRCC tissues. CONCLUSION: The low expression of miR-99b and miR-99b* contributes to ccRCC development and miR-99b acts as an onco-suppressor by suppressing IGF1R and mTOR expression to down-regulate IGF1R/AKT/mTOR signaling. IJCEP