Integrated analysis identifies microRNA-188-5p as a suppressor of AKT/mTOR pathway in renal cancer

Many current microRNA (miRNA) expression datasets for renal cell carcinoma (RCC) often show inconsistent analysis results, so a shift to comprehensive analysis of multiple datasets can effectively accelerate molecular screening for precision medicine and translational medicine research. MicroRNA (miR)-188-5p is a clinically noteworthy miRNA whose aberrant expression was previously observed in a variety of cancers, but its role in RCC is unclear. In this study, we undertook a comprehensive analysis of four RCC miRNA expression datasets and validated the results using The Cancer Genome Atlas (TCGA) dataset and a cohort of collected clinical samples. Fifteen miRNAs were identified as potential diagnostic markers by the analysis of four RCC miRNAs datasets. Analysis of the TCGA kidney renal clear cell carcinoma dataset showed significantly shorter survival in RCC patients with reduced miR-188-5p expression levels, and our collection of RCC clinical samples showed low miR-188-5p expression in the tumors. Overexpression of miR-188-5p in Caki-1 and 786-O cells inhibited cell growth, colony formation, invasion, and migration. In contrast, miR-188-5p inhibitors reversed these cell phenotypes. We identified a binding site for miR-188-5p in the 3'-UTR region of myristoylated alanine-rich C-kinase substrate (MARCKS) mRNA and demonstrated an interaction between these two molecules. Quantitative RT-PCR and western blot analysis revealed that miR-188-5p could regulate the AKT/mTOR signaling pathway through MARCKS. Mouse transplantation tumor assay indicated that miR-188-5p reduced the tumorigenicity of RCC in vivo. MicroRNA-188-5p could be a valuable new molecule for RCC diagnosis and prognosis.