Targeting Glioma Stem Cells by Functional Inhibition of a Prosurvival OncomiR-138 in Malignant Gliomas

Malignant gliomas are the most aggressive forms of brain tumors, associated with high rates of morbidity and mortality. Recurrence and tumorigenesis are attributed to a subpopulation of tumor-initiating glioma stem cells (GSCs) that are intrinsically resistant to therapy. Initiation and progression of gliomas have been linked to alterations in microRNA expression. Here, we report the identification of microRNA-138 (miR-138) as a molecular signature of GSCs and demonstrate a vital role for miR-138 in promoting growth and survival of bona fide tumor-initiating cells with self-renewal potential. Sequence-specific functional inhibition of miR-138 prevents tumorsphere formation in vitro and impedes tumorigenesis in vivo. We delineate the components of the miR-138 regulatory network by loss-of-function analysis to identify specific regulators of apoptosis. Finally, the higher expression of miR-138 in GSCs compared to non-neoplastic tissue and association with tumor recurrence and survival highlights the clinical significance of miR-138 as a prognostic biomarker and a therapeutic target for treatment of malignant gliomas. [Display omitted] ► MicroRNA-138 is a molecular signature of glioma stem cells ► Functional inhibition of miR-138 leads to apoptotic death of glioma stem cells ► MicroRNA-138 is a prosurvival oncomiR for glioma stem cells ► MicroRNA-138 is a prognostic biomarker for malignant gliomas Malignant gliomas are the most aggressive forms of brain tumors, associated with high rates of morbidity and mortality. Recurrence and tumorigenesis are attributed to a minor population of tumor-initiating cells that are resistant to therapy. Sampath and colleagues not only report the identification of microRNA-138 as a molecular biomarker for these cells but also demonstrate that microRNA-138 is a potential therapeutic target for the treatment of malignant gliomas.