1. Control of P-glycoprotein activity by membrane cholesterol amounts and their relation to multidrug resistance in human CEM leukemia cells.
- Author
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Gayet L, Dayan G, Barakat S, Labialle S, Michaud M, Cogne S, Mazane A, Coleman AW, Rigal D, and Baggetto LG
- Subjects
- ATP Binding Cassette Transporter, Subfamily B, Member 1 chemistry, ATP Binding Cassette Transporter, Subfamily B, Member 1 physiology, Adenosine Triphosphatases metabolism, Amino Acid Sequence, Apoptosis drug effects, Biological Transport drug effects, Cell Line, Tumor, Cholesterol metabolism, Cholesterol physiology, Daunorubicin metabolism, Daunorubicin pharmacology, Humans, Membrane Lipids metabolism, Membrane Lipids physiology, Membrane Microdomains chemistry, Membrane Microdomains enzymology, Membrane Microdomains metabolism, Models, Chemical, Molecular Sequence Data, Precursor Cell Lymphoblastic Leukemia-Lymphoma enzymology, Precursor Cell Lymphoblastic Leukemia-Lymphoma pathology, Proteolipids chemistry, Proteolipids metabolism, Vinblastine metabolism, Vinblastine pharmacology, ATP Binding Cassette Transporter, Subfamily B, Member 1 metabolism, Cholesterol chemistry, Drug Resistance, Multiple drug effects, Drug Resistance, Neoplasm drug effects, Membrane Lipids chemistry, Precursor Cell Lymphoblastic Leukemia-Lymphoma metabolism
- 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.
- Published
- 2005
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