Hypoxia-induced circSPECC1 drives temozolomide resistance in glioblastoma via IGF2BP2-mediated PGK1 mRNA stabilization

Glioblastoma (GBM) is a notoriously lethal brain tumor, primarily owing to its inevitable resistance to temozolomide (TMZ), a frontline chemotherapy. Hypoxia-driven metabolic adaptations have been implicated in therapeutic failure; however, the role of circular RNAs remains largely underexplored. By integrating multiomics profiling with functional assays in patient-derived GBM cells, orthotopic xenografts, and clinical specimens, this study aimed to elucidate the role of hypoxia-induced hsa_circ_0000745 (circSPECC1) in mediating TMZ resistance. Mechanistic investigation included RNA pulldown, RIP, glycolysis flux analysis, and DNA damage assessment. The circSPECC1 is overexpressed in GBM and correlates with poor prognosis. Hypoxia triggers HIF-1α-mediated transcriptional upregulation of circSPECC1, which scaffolds insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) to stabilize phosphoglycerate kinase 1 (PGK1) mRNA. Importantly, circSPECC1/PGK1 axis activation enhances glycolytic flux, blunts TMZ-induced DNA damage, and confers chemoresistance. Targeting circSPECC1 disrupts PGK1-driven glycolysis, restores TMZ sensitivity, and synergizes with TMZ to extend survival in orthotopic GBM models. In conclusion, this study identifies a previously uncharacterized HIF-1α/circSPECC1/IGF2BP2/PGK1 axis that drives metabolic adaptation and TMZ resistance in GBM. Targeting this axis overcomes acquired chemoresistance, positioning circSPECC1 as both a prognostic biomarker and a therapeutic vulnerability in hypoxic GBM niches.