Targeting The Glucose Metabolism Of Monocytic Myeloid-Derived Suppressor Cells To Stimulate Cancer Immunity

126Background: Myeloid derived suppressor cells (MDSCs) inhibit the expansion of tumor antigen-specific effector CD8+ T cells via different mechanisms including increased expression of arginase, transforming growth factor – β (TGF – β) and indoleamine 2,3-dioxygenase (IDO). Recently, MDSCs were found to over-express hypoxia inducible factor 1 alpha (HIF-1α) which is required for their differentiation. An essential transcriptional target of HIF-1α is 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) which synthesizes fructose 2,6-bisphosphate, an allosteric stimulator of glycolysis and of proliferation via stimulation of cyclin dependent kinase-1 (CDK1). We hypothesized that MDSCs might over-express PFKFB3 which in turn might be required for their function as T cell suppressors. Methods: We used monocytic MDSCs (M-MDSCs) induced by co-culture with A375 melanoma cells, M-MDSCs from metastatic melanoma patients, murine bone marrow MDSCs and splenic M-MDSCs from B16 F10 tumor bearing mice for our...