Abstract 6672: Lipid droplet accumulation after metformin and 6 aminonicotinamide combinatory treatment of glioblastoma cells

Abstract Glioblastoma (GBM) has the worst prognosis among primary brain cancers. As in many tumors, GBM proliferation is supported by glycolysis and the pentose phosphate pathway (PPP). The PPP enables cancer cells to adapt to anabolic demands, including lipid synthesis, and to restore antioxidant defenses. Metformin (MET), a worldwide prescribed drug for type-two diabetes, impairs the progression of different malignancies by indirectly inhibiting the mammalian target of rapamycin (mTOR). Our previous results showed that the combination of MET and 6-aminonicotinamide (6AN), a PPP inhibitor, strongly potentiates their individual cytotoxic effects on different tumor cells. Thus, the present work aimed to study the effect of MET alone or in combination with 6AN on the mTOR pathway as well as on the activity of acetyl-CoA carboxylase, a key enzyme in lipid synthesis, in the human GBM cell line U251. Results showed that MET (5 mM) alone or in combination with 6AN (25 µM) decreased the mTOR effector, pS6, and increased the presence of the phosphorylated form of acetyl-CoA carboxylase (24 h of treatment, determined by western blot and immunofluorescence, p<0.05). Controversially, we also found an increase in the total cell lipid content (BODIPY and oil red staining, analyzed by flow cytometry (FC), p<0.01) of MET/6AN-treated cells, which was accompanied by a mild increase in the content of the lipid transporter CD36 (FC, p<0.01). In addition, by fluorescence microscopy, we observed an increase in the number and size of lipid droplets of MET/6AN-treated cells. Finally, we also found that MET/6AN promoted a decrease in mitochondrial potential and an increase in oxidative stress and lipid peroxidation (TMRE, DCF and C11-BODIPY respectively, FC, p<0.01). Preliminary results indicated that accumulation of lipids inside lipid droplets may prevent lipid peroxidation. These results deserve to be further investigated to better understand the mechanisms involved in the effectiveness of the combination of MET/6AN as a potential strategy to treat GBM. Citation Format: Cecilia Gasco, Ivan Macharashvilli, Daniela Perez Visñuk, Marina Perona, J. Silvio Gutkind, Marcela Solange Villaverde. Lipid droplet accumulation after metformin and 6 aminonicotinamide combinatory treatment of glioblastoma cells [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 6672.