MicroRNA-575 acts as a novel oncogene via targeting multiple signaling pathways in glioblastoma.

PURPOSE: Glioblastoma (GBM) patients currently face poor survival outcomes with an average survival period of <15 months, while only 3-5% of patients survive longer than 36 months. Although the mechanisms of tumorigenesis are still being elucidated, miRNAs are promising candidates to explore as novel and prognostic biomarkers in GBM. In this study, we identified the association between miR-575 expression and overall survival (OS) of primary GBM patients and undertook functional studies to discern the contribution of miR-575 to GBM tumorigenesis. METHODS: Total RNAs were isolated from 254 FFPE GBM tumor samples and miR expression was assayed (simultaneously) using NanoString Technologies. To determine the association between miR-575 and patients' prognosis, Kaplan-Meier, univariable and multivariable Cox regression analyses were performed. Cell proliferation, colony formation, migration assays were conducted to investigate the function of miR-575 in vitro and in vivo. In silico target gene network analysis was performed to identify the putative targets of miR-575 in GBM, which were further verified by luciferase reporter assay, as well as qPCR and immunoblotting. RESULTS: Our clinical data (n = 254) show that miR-575 is associated with worse GBM OS by univariable analysis (UVA, HR = 1.27, p-value<0.001) and multivariable (MVA, HR = 1.23, p = 0.007) analysis incorporating critical clinical variables. Functional studies indicated that overexpression of miR-575 significantly increased cell proliferation and migration of GBM cells in vitro, as well as tumor growth in vivo. Subsequent in silico target gene network and mechanistic studies identified CDKN1B/p27 and PTEN, as potential targets of miR-575 in GBM. MicroRNA-575 can also regulate the activity of AKT and ERK pathways in GBM. CONCLUSION: miR-575 has prognostic value in GBM, with higher expression associating with worse OS of patients, and contributes to GBM tumorigenesis by regulating multiple signaling pathways in GBM.