Overexpression of miR-770 indicates a favorable prognosis and suppresses tumorigenesis by modulating PI3K-AKT pathway in glioma.

OBJECTIVE: Previous studies showed that miR-770 expression was deregulated in many tumors. However, the effect of miR-770 function on glioma remains as a mystery. The present study aimed to explore its expression, cellular function and clinic features in glioma. PATIENTS AND METHODS: We analyzed RNA sequencing data to explore abnormally expressed miRNAs in glioma. Glioma tissue specimens and their matched normal tissues were collected to test miR-770 expression using quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) analysis. The correlation between miR-770 and the clinicopathological factors and the prognostic value of miR-770 was statistically analyzed. We then investigated alterations in a series of cancer-related phenotypes, including cell viability, apoptosis, colony formation and metastasis capacities. Western blot analysis was performed to examine the expression changes of EMT-related proteins and PI3K/Akt signaling pathway proteins. RESULTS: We identified a novel glioma-related miRNA miR-770, which was significantly down-regulated in human glioma tissues. The results of RT-PCR further showed that miR-770 expression was significantly down-regulated in both glioma tissues and cell lines. Furthermore, decreased miR-770 expression was significantly associated with advanced WHO grade, KPS score and shorter five-year overall survival. Then, functional assays indicated that overexpression of miR-770 suppressed proliferation, migration, invasion and EMT pathway, and induced the apoptosis of glioma cells in vitro. Moreover, we further illustrated that the up-regulation of miR-770 suppressed the PI3K-AKT signaling pathway. CONCLUSIONS: Our present findings firstly reported the roles and mechanisms associated with miR-770 in glioma progression, highlighting miR-770 as a potential therapeutic target for glioma patients.