C16:0 ceramide effect on melanoma malignant behavior and glycolysis depends on its intracellular or exogenous location

To investigate the role of C16:0 ceramide in melanoma metastatic behavior and glycolysis, five common long-chain ceramides (C16:0, C18:0, C20:0, C22:0, C24:0) were tested in melanocyte and melanoma cell lines by LC-MS. We then treated non-metastatic and metastatic melanoma cells with PDMP and exogenous C16:0 to explore their effects on proliferation, migration, and glycolysis. The long-chain ceramide was also analyzed by LC-MS after treatment. C16:0 ceramide showed the highest levels in melanocyte and melanoma cells, with all melanomas higher than melanocytes. PDMP inhibited malignant behavior and glycolysis in melanoma, and caused the accumulation of intracellular C16:0. Exogenous C16:0 promoted melanoma glycolysis, but not malignant behavior, and decreased intracellular C16:0. Finally, pyruvate kinase (PK), hexokinase (HK), and lactic acid dehydrogenase (LDH) activity, key enzymes in glycolysis, were altered after treatment with PDMP and exogenous C16:0.