Beta-Hydroxybutyrate Promotes Proliferation, Migration and Stemness in a Subpopulation of 5FU Treated SW480 Cells: Evidence for Metabolic Plasticity in Colon Cancer

Abstract

Background: Beta-hydroxybutyrate (BHB) as a ketone body is the metabolic fuel in oxidative phosphorylation<br />pathway. So far the effects of BHB on the biology of tumor cells is contradictory. Therefore, we investigated the effect of<br />BHB on viability, metabolism, proliferation and migration of 5FU treated SW480 colon cancer cell line. Methods: we<br />treated the SW480 cells with IC50 dose of 5-fluorouracil (5FU) for 72 h to isolate a subpopulation of 5FU treated cells<br />that were resistant to it. Effects of BHB on cell viability was investigated by MTT assay. Measurement of oxygen<br />consumption rate (OCR) in parallel with extracellular acidification rate (ECAR) upon BHB treatment was used for<br />determination of metabolic profile of these cells. Investigating the relationship between metabolic phenotype and<br />the status of differentiation and stemness was done by analyzing the expression of PGC-1α, c-MYC, NANOG, ALPi<br />and KRT20 genes by qRT-PCR. Clonogenic and scratch assay were performed to determine the proliferation and<br />migration abilities of incubated with BHB compared to untreated cells. Results: BHB increased cell viability in SW480<br />and 5FU treated SW480 cells. The results showed a significantly decreased ECAR and increased OCR in both cell<br />types following BHB treatment reflecting the superiority of oxidative phosphorylation profile compared to glycolysis<br />in both cell types. Also, treatment with BHB increases the expression of genes normally associated with stemness<br />and mitochondrial biogenesis and decreases the expression of genes related to glycolytic program and differentiation<br />in 5FU treated cells. Self-renewal and migration potential of BHB treated cells increased significantly. Conclusion:<br />These findings suggest that BHB utilization via oxidative mitochondrial metabolism can fuel proliferation, migration<br />and stemness in 5FU treated SW480 colon cancer cells.