Coevolution of neoplastic and non-neoplastic reactive astrocyte states converges on mesenchymal-like and injury-response programs during murine glioblastoma progression and post-radiotherapy recurrence

Glioblastomas initially respond to radiotherapy but invariably recur, often within high-dose radiation treatment fields. Although stromal radiation responses are incompletely understood, evidence suggests that the tumor microenvironment becomes tumor-supportive after therapy. Using a genetically engineered glioblastoma mouse model, we profiled healthy brain, primary tumors, and post-radiotherapy recurrences with single-cell and spatial transcriptomics and immunohistochemistry. Across 13 non-neoplastic cell types and 10 tumor cell states, we mapped transcriptional adaptations accompanying progression from healthy brain to primary and recurrent glioblastoma. We identified distinct astrocyte states linked to disease stage, including reactive non-neoplastic astrocytes and tumor cells adopting reactive astrocyte-like phenotypes. Reactive astrocyte-like tumor cells with mesenchymal and injury-response signatures were enriched after radiotherapy and persisted in recurrent tumors. Receptor–ligand interactions between reactive astrocytes and tumor cells included known and putative drivers of aggressiveness. These findings highlight convergent reactive astrocyte programs in astrocytes and tumor cells as potential mediators of glioblastoma radioresistance.