Fatty acid binding protein 1 (FABP1) depletion promotes an oxidative metabolic shift in Caco-2 colorectal cancer cells.

Lipid metabolism reprogramming is a well-established hallmark of many cancer types, including colorectal cancer (CRC). Nevertheless, a clear understanding on how fatty acid (FA) metabolism is fine-tuned during CRC development and progression is still missing. Given that CRC is the second leading cause of cancer-related death, addressing these critical aspects may provide the rationale for new therapeutic approaches and early biomarker identification. Fatty acid binding protein 1 (FABP1) is a small protein that binds FA and other lipophilic compounds, acting as a lipid transporter in the intestine. Little is currently known about the function of FABP1 in CRC. Here we show that the knockdown of FABP1 in CRC cells impairs de novo FA and cholesterol synthesis, specifically, via altering the transcriptional regulation of lipid metabolism genes. FABP1 depletion suppresses the expression of FA and cholesterol synthesis-associated genes while promoting that of FA oxidation genes and mitochondrial oxidative pathways. The latter is associated with increased oxygen consumption rate and activation of the energy sensor 5' AMP-activated kinase (AMPK). Taken together, our results show that FABP1 orchestrates the balance between FA synthesis and oxidation, most likely to prevent the cytotoxic effects of circulating unbound free fatty acids. Thus, targeting FABP1 function may represent a potential therapeutic strategy in advanced CRC.