Differential microRNA Expression in Glioblastoma Neurospheres and Attached Cells Following Temozolomide and Radiation Treatment

Background Glioblastoma (GBM) remains the most aggressive primary brain tumor, characterized by profound resistance to standard therapy. Treatment failure is attributed to glioblastoma stem cells (GSCs), which exhibit self-renewal capacity and therapeutic resistance. Purpose This study investigated whether temozolomide (TMZ) and ionizing radiation (IR) differentially modulate microRNA (miRNA) expression in neurospheres versus attached cells from primary GBM cultures. Methods Primary cultures from ten IDH1-mutated GBM patients were established and separated into neurospheres (GSC-enriched) and attached cells (differentiated). Following treatment with TMZ (340 µM), IR (14 Gy), or combined TMZ + IR, expression of 47 miRNAs was analyzed by TaqMan Low Density Array with FDR correction. Results Five miRNAs demonstrated differential expression: miR-101, miR-124a, and miR-1275 showed significant upregulation in IR-treated neurospheres (p < 0.05), while miR-138 was upregulated in TMZ-treated attached cells (p < 0.03), and miR-155 was elevated in IR-treated attached cells (p < 0.01). These miRNAs regulate cell cycle, TGF-β signaling, and stem cell pathways. Conclusions Standard GBM therapies induce distinct, cell-type-specific miRNA responses. Upregulation of pro-stemness and radioresistance-associated miRNAs in treatment-resistant populations suggests these molecular changes contribute to therapeutic failure and represent novel therapeutic targets.