ATGL deletion in castration-resistant prostate cancer cell line
Lipid metabolism plays a central role in prostate cancer. To date, the major focus on prostate cancer lipid metabolism has centered on the roles of de novo lipogenesis and lipid uptake with little consideration for how cancer cells access these lipids once they are created or taken up and stored. Analysis of patient-derived phosphoproteomics data identified adipose triglyceride lipase (ATGL), a rate-limiting enzyme in the breakdown of triglycerides and previously suspected tumor suppressor, as a target of calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2)-AMP-dependent protein kinase (AMPK) signaling that, conversely, promotes castration-resistant prostate cancer (CRPC) progression. Phosphorylation of ATGL by CAMKK2-AMPK signaling increased ATGL's lipase activity, cancer cell proliferation, migration, and invasion. Shotgun lipidomics and imaging mass spectrometry demonstrated ATGL's profound regulation of prostate cancer lipid metabolism in vitro and in vivo, remodeling membrane composition. Targeting ATGL using molecular, genetic, and/or pharmacological approaches impaired the growth of human and murine prostate cancer cells in culture and xenograft mouse models of CRPC as well as organoid models. The efficacy of ATGL inhibition occurs in a glucose concentration-dependent manner. Accordingly, pharmacological inhibition or depletion of ATGL induced metabolic plasticity with a shift towards glycolysis, which could be exploited therapeutically by co-targeting both metabolic pathways. Together, these data nominate ATGL and intracellular lipolysis as a potential therapeutic target for the treatment of CRPC and provide insights for future combination therapies. Overall design: Comparative gene expression profiling analysis of RNA-seq data in isogenic ATGL knockout and addback cell lines, including wild type ATGL, a S404A mutant and a lipolytic-inactive S47A mutant. Cells were plated in RPMI1640 no glucose supplemented with 5mM glucose and 5% dialyzed FBS before harvesting for RNA sequencing. Three replicates per cell line were used.