RETRACTED: MicroRNA-186 targets IGF-1R and exerts tumor-suppressing functions in glioma (Retracted article. See vol. 26, 2022)

Glioma is the most common malignant brain tumor in adults and represents one of the most aggressive and life-threatening types of cancer in humans. Increasing studies have revealed that microRNAs are abnormally expressed in various types of human cancer, and have oncogenic or tumor suppressive roles, which depend primarily on the type of cancer. The present study aimed to investigate the expression level and effects of microRNA-186 (miR-186) on glioma, and its underlying molecular mechanism. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis was performed to detect the expression of miR-186 in glioma tissues and cell lines. Cell proliferation and invasion were assessed using MTT and cell invasion assays, respectively. Bioinformatics analysis and a luciferase reporter assay were performed to identify insulin-like growth factor 1 receptor (IGF-1R) as a novel target gene of miR-186. The mRNA expression level of IGF-1R was also measured using RT-qPCR analysis. The association between miR-186 and the expression of IGF-1R was evaluated using Spearman's correlation analysis. Furthermore, the regulatory effects of miR-186 on the mRNA and protein expression of IGF-1R were determined using RT-qPCR and western blot analyses. Finally, the biological effects of the underexpression IGF-1R on glioma cells were investigated. The results showed that miR-186 was significantly downregulated in glioma tissues and cell lines. Inducing the expression of miR-186 suppressed glioma cell proliferation and invasion. IGF-1R was confirmed as a direct target gene of miR-186. In addition, the mRNA expression of IGF-1R was upregulated and inversely correlated with that of miR-186 in glioma tissues. The effects of IGF-1R-knockdown effects induced by the overexpression of miR-186. These findings demonstrated that miR-186 acted as a tumor suppressor by targeting IGF-1R in glioma, suggesting miR-186 may be a potential therapeutic target for the treatment of this disease.