UDP-glucose ceramide glucosyltransferase promotes radioresistance via membrane reorganization to maintain redox balance in glioblastoma.

Background: Glioblastoma (GBM) is an aggressive brain tumor characterized by a poor prognosis and resistance to radiotherapy. Although multiple mechanisms of radioresistance have been proposed, the contribution of membrane-driven metabolic adaptations to radioresistance remains poorly understood.

Methods: The role of UDP-glucose ceramide glucosyltransferase (UGCG) was investigated using radioresistant GBM cell lines and in vivo xenograft models. After inhibiting UGCG function through genetic or pharmacological (miglustat) approaches, we assessed the effects on lipid raft integrity, localization of the ASCT2 transporter, glutamine uptake, oxidative stress, and radiosensitivity.

Results: UGCG was upregulated in radioresistant GBM cells and promoted lipid raft stabilization. This facilitated the membrane recruitment of the glutamine transporter ASCT2 (SLC1A5), thereby sustaining redox homeostasis under radiation stress. Genetic or pharmacological inhibition of UGCG disrupted lipid raft integrity, impaired ASCT2 localization, reduced glutamine uptake, and increased oxidative stress, leading to enhanced radiosensitivity. In GBM xenograft models, UGCG inhibition combined with radiotherapy significantly suppressed tumor growth and extended survival.

Conclusions: These findings reveal a previously underexplored, membrane-centric mechanism of radioresistance in which UGCG orchestrates lipid raft remodeling to facilitate glutamine-dependent redox balance. This highlights UGCG as a potential therapeutic target to enhance the efficacy of radiotherapy in GBM.