RESUMO
The high glucose consumption of tumour cells has been well known since Warburg's investigations. Nevertheless, the reason for this phenomenon is still a matter of speculation. Glucose uptake of tumour cells is mainly mediated by GLUT1. In this study, the question of whether glucose uptake as well as expression of GLUT1 are both related to tumour cell proliferation was addressed. Three kinetically different cell lines of colorectal adenocarcinomas (HRT-18, HT29 and CX-2) were used for the experiments. All the cell lines expressed GLUT1 at a high level, being mainly localized within the cell membrane and the endoplasmic reticulum. Surprisingly, the highest expression of GLUT1 was found in the most slowly proliferating cell line, CX-2. Moreover, induction of cell cycle arrest increased both GLUT1 expression and glucose consumption, as well as global protein synthesis. These data suggest that the protein synthesis of tumour cells is much more glucose-consuming than proliferation and that both processes are inversely related.