Methods for malignant glioma diagnosis/prognosis using miR-138 as a prognostic biomarker and methods for treating malignant glioma and inhibiting glioma stem cell growth by suppressing miR-138. Also disclosed herein are pharmaceutical compositions for use in treating malignant glioma, prolonging survival of malignant glioma patients, or eliminating GSCs and in turn tumor growth, the pharmaceutical composition comprising an oligonucleotide that targets miR-138.
