CNSC-19. ISCHEMIC STROKE DRIVES GLIOMA PROGRESSION BY REMODELING TUMOR-ASSOCIATED ASTROCYTES

Abstract Ischemic stroke and glioma are two deadly neurological disorders worldwide. Recent epidemiological studies reveal an increased risk of brain tumors, notably glioma, in patients with a history of stroke, resulting in a 10% co-occurrence. Comparative transcriptome analyses of brain samples collected from patients with common neurological disorders show that glioma is particularly enriched with stroke-associated gene signatures, especially in pathways related to their shared pathological features. These findings suggest a stroke-glioma interrelationship; however, it remains unknown how stroke alters the brain microenvironment to drive tumor progression. Here, we induced photothrombotic stroke in three mouse glioma models recapitulating multiple aspects of human glioma. Across all glioma models, we consistently observed that stroke increases tumor proliferation and infiltration towards stroke-affected regions, accompanied by reduced survival compared to sham control groups. Further analyses using single-cell RNA sequencing and spatial transcriptomic profiling in our stroke-glioma models reveal pronounced stroke-induced glioma microenvironment changes, among which tumor-associated astrocytes (TAAs) are most dramatically remodeled. Remarkably, we identified a unique stroke-induced astrocyte (SAA) at the tumor leading edge of the stroke-glioma group, characterized by diminished physiological astrocyte signatures and increased chromosomal and metabolic reprogramming. Among the top differentially expressed genes in SAA compared with TAA, the sodium-bicarbonate cotransporter Slc4a4 is interesting due to its enriched expression in TAA in both human and mouse gliomas, and it is significantly down-regulated at the infiltrating tumor edge. Consequently, we examine whether restoring astrocytic Slc4a4 expression rescues stroke-induced glioma progression. We found that astrocytic Slc4a4 overexpression reduces glioma growth and infiltration, accompanied by extended astroglial scar formation. Collectively, our study demonstrates that a subset of TAAs induced by stroke exacerbates glioma pathology, highlighting an indispensable astrocytic contribution to the stroke-glioma interaction.