Targeting miR-9 in Glioma Stem Cell-Derived Extracellular Vesicles: A Novel Diagnostic and Therapeutic Biomarker

Background: Glioblastoma (GBM) is a lethal brain tumor with no effective strategies in early diagnosis and treatment. This study was aimed to assess the miRNA expression profiles in EVs from CSF and tissue of glioblastoma patients to identify significantly upregulated miRNAs and investigate the underlying neoplastic mechanisms. Methods: EVs were measured by TEM and NTA assays. Differentially regulated miRNAs were measured using RNA sequencing in GBM CSF EVs and in GBM tissues compared with controls. RT-qPCR was employed to analyze miRNA and gene expression. Luciferase report assay was used to investigate gene target of miR-9. The proliferation ability was detected by EdU and CCK-8 experiment while cell migration was measured by transwell and wound healing assay. Results: The expression level of miR-9 was significantly higher in GBM CSF EVs and tissues than controls (p = 0.038). The area under curve for CSF EV miR-9 was 0.800 (95% CI: 0.583–1.000, p = 0.033). The expression of miR-9 was significantly higher in Glioma stem cells (GSCs) and GSC-derived EVs than in glioblastoma cells. GSC-derives EVs could promote GBM growth and migration Moreover, inhibition of miR-9 in GSCs showed the reverse anti-tumor effects through secreted EVs. MiR-9 could bind to the 3’UTR region of DACT3 and suppress its expression. The miR-9/DACT3 axis might attribute to GBM malignant phenotype. Conclusion: MiR-9 in CSF EVs may act as a novel diagnostic biomarker for GBM and targeting miR-9 by GSC-derived EVs may be a specific and efficient strategy for GBM biotherapy.