Facilitative glucose transporter expression in human cancer tissue.

Glucose utilisation by cancer cells is greatly enhanced when compared with that by normal tissue. Glucose is taken up by cells and then phosphorylated to glucose-6-phosphate. Facilitative hexose uptake is achieved by five transmembrane transporters, termed glut1-5, which are protein products of their respective GLUT genes. Glut types differ in their kinetics, which are tailored to the requirements of the cell type they serve, although more than one glut may be expressed by a particular cell type. Herein are reviewed the results from approximately 30 studies which examined glut expression in human cancer tissue. These studies measured GLUT messenger RNA (mRNA) either using the reverse-transcriptase polymerase chain reaction or by Northern blot analysis, or detected glut proteins using the appropriate antibodies. Tumour tissue is frequently associated with the abnormal and/or over-expression of gluts, especially glut1. Some tumour cells express specific GLUT mRNA but not the respective protein. Some studies have reported associations between glut expression and proliferative indices, whilst others suggest that glut may be of prognostic significance, especially in lung cancer.