HILPDA Repression Induces Methuosis in Breast and Liver Cancer Cells by Dysregulating Lipid Metabolism

Perturbation of macropinocytosis triggers methuosis, a non-apoptotic cell death characterized by cytoplasmic vacuolization. However, the regulatory mechanisms of methuosis remain poorly defined. Lipid metabolism dysregulation is implicated in various cell death pathways, while its role in methuosis has remained elusive. Herein, LXX-8250, an isopropanolamine derivative of β-elemene, induced a vacuolization-associated cell death in breast and liver cancer cell lines. This process was accompanied by massive macropinocytosis, thereby confirming the occurrence of methuosis. Mechanistically, hypoxia-inducible lipid droplet-associated protein (HILPDA), a key regulator that promotes intracellular triacylglycerol (TAG) accumulation, was identified as the direct target of LXX-8250. By suppressing HILPDA, LXX-8250 inhibited diacylglycerol O-acyltransferase 1 (DGAT1) and activated adipose triglyceride lipase (ATGL). Consequently, lipid droplets and cellular TAG levels were reduced, while the subsequent increased diacylglycerol (DAG) stimulated macropinosome formation, leading to methuosis in these cells. In this study, we discover a novel methuosis agonist LXX-8250, and elucidate the critical role of HILPDA repression-dysregulated lipid metabolism in methuosis. Our study highlighted the potential of targeting this pathway as a therapeutic strategy to trigger cancer cell death.