PRMT1 regulates glioblastoma stemness and immunosuppression via nitric oxide metabolism: Multi-cohort analysis and experimental validation.

[BACKGROUND] Glioblastoma is the most common primary malignant brain tumor with poor prognosis. The immunosuppressive microenvironment and cancer stem cells (CSCs) drive therapeutic resistance. The role of nitric oxide (NO) metabolism in coordinating glioma stemness and immune evasion remains unclear.

[METHODS] We performed multi-omics analysis using CGGA, TCGA, and Rembrandt datasets (n = 1500) and single-cell RNA sequencing (n = 65,655 cells). PRMT1 was identified as a key NO metabolism-associated prognostic gene through Cox regression and LASSO modeling. Validation used glioma cell lines, patient-derived GSCs, and orthotopic mouse models.

[RESULTS] NO metabolism activity increased with glioma grade and correlated with poor survival (p < 0.001). Single-cell analysis showed positive correlation between NO metabolism and stemness (R = 0.35, p < 0.001). High-NO metabolism tumors showed M0 macrophage enrichment (p < 0.001) and M1 depletion (p < 0.05). PRMT1 expression was elevated in high-grade gliomas and correlated with NOS2 (R = 0.26-0.46, p < 0.001). PRMT1 knockdown reduced proliferation (76%), colony formation (75%), and CD133+ cells (11.74% to 3.11%). NO donor treatment rescued knockdown effects. In vivo PRMT1 silencing reduced tumor growth to 35% of controls (p < 0.001) and decreased SOX2 and PD-L1 expression.

[CONCLUSIONS] PRMT1 links NO metabolism to glioma stemness and immunosuppression by regulating stemness factors (OCT4, SOX2) and immune checkpoints (PD-L1) through NO-dependent mechanisms. PRMT1 represents a therapeutic target that could disrupt stem cell populations and remodel the immunosuppressive microenvironment.