DDRE-23. A COMPREHENSIVE CHARACTERIZATION OF THE GBM LIPIDOME REVEALS A MOLECULARLY-DEFINED SUB-GROUP WITH HEIGHTENED SENSITIVITY TO LIPID PEROXIDATION INDUCED CELL DEATH

Cancers, including the universally lethal glioblastoma (GBM), have reprogrammed lipid metabolism to fuel tumor growth and promote survival. However, the full extent to which lipid content is altered across molecularly heterogeneous patient tumors has yet to be fully elucidated. Additionally, the molecular alterations responsible for aberrant lipid metabolism, and the potential for identifying new therapeutic opportunities are not fully understood. To systematically investigate the GBM lipidome, we performed integrated transcriptomic, genomic and shotgun lipidomic analysis of an extensive library of molecularly diverse patient-derived GBM tumors across tumor microenvironments both in vivo (n=23) and in vitro (n=30). Using this comprehensive approach, we discovered two GBM sub-groups defined by their combined molecular and lipidomic profile. Triacylglycerides (TAGs) enriched in polyunsaturated fatty acids (PUFAs) were among the most significantly altered lipids between the two groups of GBM tumors. TAGs are the main components of lipid droplets, which have been shown to sequester PUFAs away from membrane phospholipids where their sensitivity to peroxidation leads to cell death. The GBM subgroup with a depletion of PUFA TAGs showed heightened sensitivity to lipid peroxidation both under basal conditions and in response to pro-oxidant compounds in vitro. Our findings suggest a novel association between specific molecular signatures of GBM, lipid metabolism and lipid peroxidation-induced cell death. This relationship may present a new therapeutic opportunity to target reprogrammed lipid metabolism in a molecularly-defined subset of GBMs.