title: Effect of plasma membrane cholesterol depletion on glucose transport regulation in leukemia cells.
abstract: 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.
authors.affiliation: Biochemistry Department G Moruzzi, Alma Mater Studiorum-University of Bologna, Bologna, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Caliceti
authors.forename: Laura
authors.initials: L
authors.lastname: Zambonin
authors.forename: Cecilia
authors.initials: C
authors.lastname: Prata
authors.forename: Francesco
authors.initials: F
authors.lastname: Vieceli Dalla Sega
authors.forename: Gabriele
authors.initials: G
authors.lastname: Hakim
authors.forename: Silvana
authors.initials: S
authors.lastname: Hrelia
authors.forename: Diana
authors.initials: D
authors.lastname: Fiorentini
mesh_terms: D001549:Benzamides; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D049109:Cell Proliferation; D002470:Cell Survival / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism* / Q000502:physiology; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1 / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D000068877:Imatinib Mesylate; D007938:Leukemia; D009761:Nystatin / Q000494:pharmacology; D010693:Phloretin / Q000494:pharmacology; D051966:Phospholipase C gamma / Q000378:metabolism; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D019089:Stem Cell Factor / Q000494:pharmacology / Q000502:physiology; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: C412373:AG 1879; D001549:Benzamides; D051272:Glucose Transporter Type 1; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; C495677:SLC2A1 protein, human; D019089:Stem Cell Factor; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D009761:Nystatin; D000068877:Imatinib Mesylate; D002784:Cholesterol; D011505:Protein-Tyrosine Kinases; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D051966:Phospholipase C gamma; D005947:Glucose; D010693:Phloretin