Single-cell transcriptomics reveal PRRC1 as a malignant cell enriched driver of DNA repair and therapy resistance in glioblastoma.

Glioblastoma (GBM) is the most aggressive primary brain tumor and remains largely refractory to radiotherapy and temozolomide-based therapy. Although these treatments induce DNA damage, GBM cells frequently survive by activating DNA damage response (DDR) signaling, checkpoint pathways, and stress-adaptive programs. While core DNA repair enzymes are well characterized, regulatory factors that modulate DDR-associated cellular states in malignant GBM cells remain incompletely understood. We performed unbiased multi-omics analyses integrating single-cell RNA sequencing, bulk transcriptomic cohorts, and TCGA DNA methylation data, which identified proline-rich coiled-coil 1 (PRRC1) as a top candidate gene. PRRC1 is poorly characterized in cancer, and its role in GBM has not been defined. Functional annotation using Gene Ontology, MetaCore pathway enrichment, and gene set enrichment analysis revealed strong associations with chromatin organization, cell-cycle regulation, and DDR-related programs, including homologous recombination and checkpoint signaling. Pharmacogenomic correlations were evaluated using GDSC datasets, and exploratory molecular docking was performed using an AlphaFold-predicted PRRC1 structure. PRRC1 expression was significantly elevated in GBM compared with normal brain tissue, increased with glioma grade, and correlated with reduced patient survival. Single-cell analysis demonstrated preferential enrichment of PRRC1 in malignant tumor populations with minimal expression in non-malignant cells. Functional validation using shRNA-mediated knockdown in U87 and patient-derived GBM cells showed marked reductions in proliferation, clonogenic survival, anchorage-independent growth, and three-dimensional spheroid formation. Under genotoxic stress, PRRC1-deficient cells exhibited enhanced γ-H2AX accumulation, indicating increased DNA damage signaling burden and reduced stress tolerance. Collectively, these findings indicate that PRRC1 supports proliferative and stress-adaptive transcriptional states in GBM, and its suppression compromises tumor cell fitness, highlighting PRRC1 as a potential therapeutic vulnerability in glioblastoma.