Exploring CSF microRNA signatures as diagnostic biomarkers in adult-type diffuse gliomas

Mutations in isocitrate dehydrogenase (IDH) genes, specifically IDH1 and IDH2, are frequently observed in diffuse gliomas (DG) and define distinct molecular subtypes, namely IDH-wildtype and IDH-mutant. Abnormal expression of extracellular vesicle-derived microRNAs (EV-miRNAs) in the cerebrospinal fluid (CSF) of DG patients may serve as minimally invasive diagnostic and prognostic biomarkers. To investigate this potential, we employed miRNA-sequencing (miRNA-seq), quantitative real-time PCR (qRT-PCR), and multivariable logistic regression (MLR) to identify differentially expressed microRNAs (DE-miRNAs) in CSF samples from DG patients. qRT-PCR analysis demonstrated that EV-miR-21-5p effectively differentiated CSF from glioblastoma (GBM) patients versus controls (p = 0.012, AUC = 0.84) and IDH-mutant gliomas versus controls (p = 0.003, AUC = 0.93). MLR identified five miRNAs (miR-150-5p, miR-142-3p, miR-19b-3p, miR-99a-5p, and miR-27b-3p) that accurately distinguished IDH-wildtype from IDH-mutant gliomas (AUC = 1.00), while GBM CSF was reliably separated from controls (AUC = 1.00) based on significantly reduced levels of nine miRNAs, including miR-1298-5p, miR-1911-5p, miR-195-5p, miR-196a-5p, miR-26a-5p, miR-26b-5p, miR-30a-3p, miR-30a-5p, and miR-30e-5p. Notably, miR-142-3p alone achieved complete discrimination of IDH-mutant gliomas from controls (AUC = 1.00). Ingenuity Pathway Analysis (IPA) revealed that miR-16-5p and other miRNAs with seed AGCAGCA formed the largest interaction network in GBM, while disease enrichment analysis using Database for Annotation, Visualization, and Integrated Discovery (DAVID) confirmed that the 1000 predicted mRNA targets of DE-miRNAs in GBM were disease relevant. Collectively, these findings identify a robust panel of CSF-derived miRNAs capable of distinguishing IDH-mutant gliomas, GBM, and non-tumor states, supporting the potential of EV-miRNAs as minimally invasive biomarkers for the molecular characterization of diffuse gliomas.