title: Control of P-glycoprotein activity by membrane cholesterol amounts and their relation to multidrug resistance in human CEM leukemia cells.
abstract: P-glycoprotein (P-gp) is the most well-known ATP-binding cassette (ABC) transporter involved in unidirectional substrate translocation across the membrane lipid bilayer, thereby causing the typical multidrug resistance (MDR) phenotype expressed in many cancers. We observed that in human CEM acute lymphoblastic leukemia cells expressing various degrees of chemoresistance and where P-gp was the sole MDR-related ABC transporter detected, the amount of esterified cholesterol increased linearly with the level of resistance to vinblastine while the amounts of total and free cholesterol increased in a nonlinear way. Membrane cholesterol controlled the ATPase activity of P-gp in a linear manner, whereas the P-gp-induced daunomycin efflux decreased nonlinearly with the depletion of membrane cholesterol. All these elements suggest that cholesterol controls both the ATPase and the drug efflux activities of P-gp. In addition, in CEM cell lines that expressed increasing levels of elevated chemoresistance, the amount of P-gp increases to a plateau value of 40% of the total membrane proteins and remained unvaried while the amount of membrane cholesterol increased with the elevation of the MDR level, strongly suggesting that cholesterol may be directly involved in the typical MDR phenotype. Finally, we showed that the decreased daunomycin efflux by P-gp due to the partial depletion of membrane cholesterol was responsible for the efficient chemosensitization of resistant CEM cells, which could be totally reversed after cholesterol repletion.
authors.affiliation: Institut de Biologie et Chimie des Protéines (IBCP UMR5086 CNRS UCBL), 7 Passage du Vercors, F-69367 Lyon Cedex 07, France.
authors.forename: Landry
authors.initials: L
authors.lastname: Gayet
authors.forename: Guila
authors.initials: G
authors.lastname: Dayan
authors.forename: Stéphane
authors.initials: S
authors.lastname: Barakat
authors.forename: Stéphane
authors.initials: S
authors.lastname: Labialle
authors.forename: Mickaël
authors.initials: M
authors.lastname: Michaud
authors.forename: Sylvain
authors.initials: S
authors.lastname: Cogne
authors.forename: Abdellah
authors.initials: A
authors.lastname: Mazane
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Coleman
authors.forename: Dominique
authors.initials: D
authors.lastname: Rigal
authors.forename: Loris G
authors.initials: LG
authors.lastname: Baggetto
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects; D001692:Biological Transport / Q000187:drug effects; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D003630:Daunorubicin / Q000378:metabolism / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D006801:Humans; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D021962:Membrane Microdomains / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D008956:Models, Chemical; D008969:Molecular Sequence Data; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D011510:Proteolipids / Q000737:chemistry / Q000378:metabolism; D014747:Vinblastine / Q000378:metabolism / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D008563:Membrane Lipids; D011510:Proteolipids; D014747:Vinblastine; D002784:Cholesterol; D000251:Adenosine Triphosphatases; D003630:Daunorubicin