Abstract 4685: Targeting fatty acid oxidation improves radiation sensitivity in glioblastoma

Background: Glioblastoma (GBM) is the most aggressive primary brain tumor, with a median survival of less than two years. A significant barrier to effective treatment is GBM's resistance to standard therapies, including radiation. This resistance is partially attributed to glioblastoma cancer stem cells (GSCs), a subpopulation with self-renewal capacity and the ability to regenerate all tumor components. Alterations in metabolic pathways, including fatty acid metabolism, are critical to GSC-mediated resistance. While fatty acid metabolism is known to be upregulated in GBM, its specific role in radiation-resistant GSCs remains poorly understood. Here, we investigated the impact of fatty acid metabolism inhibition on GSC radiation sensitivity. Methods: Two human GBM cell lines were treated for 72 hours with perhexiline, a carnitine acyltransferase 1a/b inhibitor, or vehicle control. The IC25 was determined using the SRB assay and validated with cell counts. Cells were subsequently treated with the IC25 concentration of perhexiline and irradiated with a single dose of either 0 Gy or 8 Gy. Sphere formation assays and immunoblotting for stemness markers were performed. All experiments were conducted in triplicate for statistical rigor. Results: The IC25 for perhexiline was determined to be 3 μM. Sphere formation assays using 3μM perhexiline combined with radiation revealed a significant reduction in both sphere number (p < 0.0001) and sphere size (350 μm vs. 125 μm). Immunoblotting demonstrated a decrease in stemness markers CD44 and nestin following drug treatment compared to vehicle control. Conclusion: These findings suggest that perhexiline, an FDA-approved drug, enhances radiation sensitivity in GBM by targeting GSCs. The observed reduction in sphere formation and stemness marker expression highlights its potential as a GSC-directed therapy. Further studies are warranted to explore the therapeutic potential of perhexiline in overcoming radiation resistance and improving outcomes for GBM patients. Citation Format: Tingting Huang, Kenneth Austin, Todd W. Miller, Kelli B. Pointer. Targeting fatty acid oxidation improves radiation sensitivity in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4685.