Project Abstract Lethal small molecules are powerful tools to discover and characterize new cell death mechanisms that may be useful for cancer treatment. Using small molecules, we have identified an unconventional form of non-apoptotic cell death that is distinct from apoptosis, ferroptosis, and other known forms of cell death. This lethal mechanism requires protein palmitoylation and involves the disruption of protein trafficking. In this research we propose to test the role of lipid metabolic enzymes that may positively or negatively regulate palmoptosis. One Aim of this research will focus on the lipid metabolic enzyme TECR (trans-2,3-enoyl-CoA reductase). We will test the hypothesis that TECR synthesizes palmitate that is used by protein palmitoylation enzymes to drive cell death via altered protein trafficking. A second Aim of this research will test the hypothesis that cell death is triggered by the disruption of phosphatidylcholine metabolism, which alters protein trafficking. A third Aim of this research will test the hypothesis that this new cell death mechanism can be activated in genetically engineered mouse models of cancer by a clinical drug candidate. While this cell death mechanism can be activated in diverse cancers, a major focus of the proposed studies is on sarcoma, which is highly sensitive to this lethal mechanism and for which new treatments are urgently needed. Together, these studies will define a new form of cell death and associated biochemical mechanisms that may be exploited for the treatment of sarcoma and other cancers.