GLUT1 is the predominant
glucose transporter in
leukemia cells, and the modulation of
glucose transport activity by
cytokines, oncogenes or metabolic stresses is essential for their survival and proliferation. However, the molecular mechanisms allowing to control GLUT1 trafficking and degradation are still under debate. In this study we investigated whether plasma membrane
cholesterol depletion plays a role in
glucose transport activity in M07e cells, a human
megakaryocytic leukemia line. To this purpose, the effect of
cholesterol depletion by methyl-β-
cyclodextrin (MBCD) on both GLUT1 activity and trafficking was compared to that of the
cytokine Stem Cell Factor (SCF). Results show that, like SCF, MBCD led to an increased
glucose transport rate and caused a subcellular redistribution of GLUT1, recruiting intracellular transporter molecules to the plasma membrane. Due to the role of caveolae/
lipid rafts in GLUT1 stimulation in response to many stimuli, we have also investigated the GLUT1 distribution along the fractions obtained after non ionic
detergent treatment and density gradient centrifugation, which was only slightly changed upon MBCD treatment. The data suggest that MBCD exerts its action via a
cholesterol-dependent mechanism that ultimately results in augmented GLUT1 translocation. Moreover,
cholesterol depletion triggers GLUT1 translocation without the involvement of c-kit signalling pathway, in fact MBCD effect does not involve Akt and PLCγ phosphorylation. These data, together with the observation that the combined MBCD/SCF cell treatment caused an additive effect on
glucose uptake, suggest that the action of SCF and MBCD may proceed through two distinct mechanisms, the former following a signalling pathway, and the latter possibly involving a novel
cholesterol dependent mechanism.