Abstract: The study aims to investigate the role of glutamine synthetase (GS) in radiotherapy-induced ferroptosis in glioma. The glioma cells GL261 were treated using Ionizing radiation (IR) and GS inhibitor (L-methionine sulfoximine, MSO). The levels of reactive oxygen species (ROS) was detected with the DCFH-DA fluorescent probe. The changes in glutathione (GSH) content were measured using a GSH assay kit. Cellular lipid peroxidation levels were investigated with the C11-BODIPY 581/591 fluorescent probe. The expression of the ferroptosis marker PTGS2 was detected by RT-qPCR. Cell proliferation rate and cell viability were assessed using CCK-8 assay. The effects of MSO and RT on growth inhibition of tumors were further investigate by establishing murine orthotopic glioma model. The results showed that inhibiting the activity of GS promoted the production of ROS and GSH depletion in cells after radiotherapy, enhanced lipid peroxidation, up-regulated the expression of PTGS2, and significantly inhibited cell proliferation and viability. Animal experiments confirmed that the combination of MSO and radiotherapy showed a stronger tumor suppression effect compared to conventional radiotherapy. In conclusion, inhibiting glutamine synthetase can significantly enhance the induction of ferroptosis in glioma cells by radiotherapy. This approach increases the sensitivity of tumor cells to radiotherapy and provides new strategies and targets for clinical treatment.

Key words: glioma, glutamine synthetase, L-methionine sulfoximine；radiotherapy, ferroptosis