ECM2-associated ITGB1/FAK-EGFR/ERK adhesion signaling promotes irradiation-stress adaptation in glioblastoma

Glioblastoma (GBM) recurrence after radiotherapy is shaped by adaptive malignant states, extracellular matrix (ECM) remodeling, and adhesion-dependent survival signaling. However, ECM-associated mediators that participate in irradiation-stress adaptation remain incompletely defined. We integrated bulk transcriptomic analysis of GSE253464, longitudinal single-cell RNA sequencing analysis of GSE253648, TCGA glioma survival analysis, inferred ligand-receptor analysis, hypothesis-generating virtual perturbation, transcription-factor activity analysis, and experimental studies in GBM cell and xenograft models. Functional assays, co-immunoprecipitation, Western blotting, irradiation-response assays, clonogenic survival assays, and subcutaneous GSC20 xenografts were used to examine ECM2-associated adhesion signaling. Bulk transcriptomic analysis identified ECM2 as a therapy-associated ECM/adhesion candidate in GBM. Longitudinal scRNA-seq showed that ECM2-positive malignant states were enriched for ECM, focal adhesion, mechanotransduction, and irradiation-stress programs. Inferred ligand-receptor analysis and virtual perturbation nominated an ECM2-associated ITGB1/FAK-EGFR/ERK transcriptional axis involving TEAD, AP-1, STAT, and ETS/ELK activity. Co-immunoprecipitation detected ECM2 in ITGB1-containing immunoprecipitates. ECM2 depletion altered adhesion-associated cytoskeletal organization, reduced YAP/TAZ nuclear localization, attenuated basal and EGF-induced FAK/EGFR/ERK signaling, and enhanced irradiation-associated γ-H2AX, p21, and cleaved caspase-3 responses. ITGB1 re-expression restored FAK/Paxillin/ERK phosphorylation and partially alleviated irradiation-associated responses, supporting an ITGB1-associated adhesion signaling mechanism. In an ectopic subcutaneous GSC20 xenograft model, ECM2 depletion was associated with reduced tumor growth in the context of combined TMZ plus local irradiation. These findings identify ECM2-associated ITGB1/FAK–EGFR/ERK adhesion signaling as an experimentally supported mechanism associated with GBM irradiation-stress adaptation. This study supports an ECM/adhesion-centered model in which ECM2 helps sustain pro-survival adhesion and growth-factor signaling under irradiation stress, providing a potential molecular framework for understanding therapy-adaptive GBM states. The ectopic xenograft findings provide in vivo support for ECM2-associated tumor growth. Not applicable.