Overexpression of GLUT3 promotes metastasis of triple-negative breast cancer by modulating the inflammatory tumor microenvironment.

Triple-negative breast cancer (TNBC) exhibits a higher level of glycolytic capacity and are commonly associated with an inflammatory microenvironment, but the regulatory mechanism and metabolic crosstalk between the tumor and tumor microenvironment (TME) are largely unresolved. Here, we show that glucose transporter 3 (GLUT3) is particularly elevated in TNBC and associated with metastatic progression and poor prognosis in breast cancer patients. Expression of GLUT3 is crucial for promoting the epithelial-to-mesenchymal transition and enhancing invasiveness and distant metastasis of TNBC cells. Notably, GLUT3 is correlated with inflammatory gene expressions and is associated with M1 tumor-associated macrophages (TAMs), at least in part by C-X-C Motif Chemokine Ligand 8 (CXCL8). We found that expression of GLUT3 regulates CXCL8 production in TNBC cells. Secretion of CXCL8 participates in GLUT3-overexpressing TNBC cells-elicited activation of inflammatory TAMs, which further enhances GLUT3 expression and mobility of TNBC cells. Our findings demonstrate that aerobic glycolysis in TNBC not only promotes aggressiveness of tumor cells but also initiates a positive regulatory loop for enhancing tumor progression by modulating the inflammatory TME.