P10.36.B ROLE OF AMPK IN GLIOBLASTOMA BIOENERGETICS

Abstract BACKGROUND Glioblastoma is the most prevalent and aggressive primary brain tumor. AMP-activated kinase (AMPK), the main energy sensor of the cell, has been previously described by our group as a key factor in glioblastoma oncogenesis and proliferation and is known for taking part in tumoral metabolic transformation. Our group has also formerly reported how AMPK regulates the expression of lipoprotein receptors and alters lipid reliance of glioblastoma cells, suggesting AMPK orchestrates nutrient dependency and flexibility on glioblastoma. Overall, this evidence positions AMPK inhibition as a promising antitumoral therapy for glioblastoma. MATERIAL AND METHODS To further study the role of AMPK in glioblastoma bioenergetics, we used the human glioblastoma cell lines U87 and U373 and silenced AMPK by transfecting the cells with a siRNA for AMPKα1/2. To assess mitochondrial function (OCR), fuel oxidation, and glycolytic parameters (ECAR), we carried out Seahorse metabolic analyses. This technology provides non-invasive and real-time monitoring of glycolytic and mitochondrial metabolic profiles. The expression of genes related to mitochondrial energetics (CPT1C, PPARGC1A, and PPARA) in these cells was studied using RT-qPCR. We are also currently studying lactate dehydrogenase (LDH) function and expression, as well as glutamine metabolism. RESULTS Our data show that silencing of AMPKα1/2 reduces basal and maximum mitochondrial respiration, as well as decreases the expression of CPT1C, PPARGC1A, and PPARA. Altogether, these results suggest alterations in mitochondrial energetic pathways. Our results do not reveal a significant effect of AMPK on the glycolytic activity of these glioblastoma cell lines. Finally, we found a great capacity of these cells to use glucose, but also fatty acids and glutamine as energy substrates, although with a very high dependency on glucose. CONCLUSION Even though in glioblastoma cells there is an increment in aerobic glycolysis (Warburg effect), these tumoral cells still maintain an elevated mitochondrial activity and a great capacity to use lipids as a fuel. AMPK plays an important role in regulating glioblastoma mitochondrial activity and bioenergetics. The authors would like to acknowledge the Funding for the Consolidation of Competitive Groups of Research (ED431B 2020/26, Xunta de Galicia, 2020-2022).