EXPRESSION OF THE FRUCTOSE TRANSPORTER GLUT5 IN HUMAN BREAST-CANCER

The primary metabolic characteristic of malignant cells is an increase d uptake of glucose and its anaerobic metabolism. We studied the expre ssion and function of the glucose transporters in human breast cancer cell lines and analyzed their expression in normal and neoplastic prim ary human breast tissue. Hexose uptake assays and immunoblotting exper iments revealed that the breast carcinoma cell lines MCF-7 and MDA-468 express the glucose transporters GLUT1 and GLUT2, isoforms expressed in both normal and neoplastic breast tissue. We also found that the br east cancer cell lines transport fructose and express the fructose tra nsporter GLUT5. Immunolocalization studies revealed that GLUT5 is high ly expressed in vivo in human breast cancer but is absent in normal hu man breast tissue. These findings indicate that human breast cancer ce lls have a specialized capacity to transport fructose, a metabolic sub strate believed to be used by few human tissues. Identification of a h igh-affinity fructose transporter on human breast cancer cells opens o pportunities to develop novel strategies for early diagnosis and treat ment of breast cancer.