Metabolic crosstalk between fatty acid oxidation and glycolysis underlies glioblastoma viability

Metabolic rewiring supports glioblastoma (GB) progression, yet the contribution of fatty acid oxidation (FAO) to GB metabolic plasticity remains poorly defined. GB tumors display elevated expression of FAO-related genes, including carnitine palmitoyltransferase 1A (CPT1A), suggesting a potential reliance on this pathway. Here, we evaluated the functional relevance of FAO in U251 GB cells using etomoxir (ETO), a CPT1A inhibitor. ETO markedly reduced cell viability in monolayers (5-day exposure) and 3D spheroids (9-day exposure; IC50=118 µM) and rapidly disrupted spheroid architecture within 48 hours. Short-term treatment with 200 µM ETO did not alter cell size or granularity, but FAO inhibition induced a clear metabolic shift characterized by increased glucose consumption, elevated lactate release, and enhanced extracellular acidification, consistent with compensatory glycolytic upregulation. To test whether this adaptive response creates a metabolic vulnerability, we inhibited glycolysis with 2-deoxyglucose (2DG). Combined ETO+2DG treatment significantly potentiated cytotoxicity compared with either agent alone after 72 hours. These findings indicate that FAO serves as a relevant energy source in GB cells and that its inhibition triggers increased glycolytic flux as a compensatory mechanism. Together, our data reveal a targetable FAO-glycolysis crosstalk in GB and support the therapeutic potential of dual metabolic pathway inhibition to exploit GB metabolic flexibility.