Single-Cell Multiomic Profiling Uncovers Radiation Dosage-Sensitive, Cluster-Specific Regulatory Dynamics in Glioblastoma

Glioblastoma (GBM) is an aggressive brain tumor that inevitably recurs after chemoradiotherapy, resulting in poor patient outcomes. Given GBM's cellular heterogeneity, we hypothesized that radiation induces sub-population specific alterations to survive and adapt to radiation stress. We performed integrated single-cell RNA-seq and ATAC-seq analyses in Glioma Stem-Like Cultures three hours after they were exposed to clinically relevant radiation doses. Radiation reshaped the cellular landscape, altering both cell type composition and GBM subtype distribution. Cluster-specific and shared transcriptional programs were induced in a dose-dependent manner, with differentially expressed genes enriching distinct biological pathways. Chromatin accessibility analyses revealed parallel cluster-specific remodeling, with both opening and closing of regulatory elements linked to functional pathway shifts. Notably, 2 Gy and 6 Gy exposures elicited conserved transcriptional profiles in RNA clusters across different radiation doses. Together, these results highlight immediate radiation-induced transcriptional and chromatin remodeling programs in GBM at single-cell resolution and identify conserved cluster-specific adaptations that may underlie therapeutic resistance.