Non-dietary Fructose Metabolism Contributes to the Warburg effect in Cancers

Abstract Fructose metabolism is increasingly recognized as a preferred energy source for cancer cell proliferation. However, dietary fructose rarely enters the bloodstream. Therefore, it remains unclear how cancer cells acquire a sufficient amount of fructose to supplement their energy needs. Here we report that the cancer cells can convert glucose into fructose through intra- and extracellular polyol pathways. The fructose metabolism bypasses normal aerobic respiration’s self-control to supply excessive metabolites to glycolysis and causes the Warburg effect. Inhibition of fructose production drastically suppressed glycolysis and ATP production in cancers. Furthermore, we determined that a glucose transporter, SLC2A8/GLUT8, exports intracellular fructose to other cells in the tumor microenvironment. Taken together, our study identified overlooked fructose resources for cancer cells as an essential part of their metabolic reprogramming and caused the Warburg effect. Statement of Significance Our findings in this study suggest that the Warburg effect is actually achieved by means of fructose metabolism, instead of glucose metabolism alone. Fructose metabolism results in accelerated glycolysis and an increased amount of ATP and key intermediates for anabolic metabolism.