title: Protein kinase C effectors bind to multidrug ABC transporters and inhibit their activity.
abstract: P-Glycoprotein and homologous multidrug transporters contain a phosphorylatable linker sequence that was proposed to control drug efflux on the basis that it was indeed phosphorylated in vitro and in vivo, and that inhibitors of protein kinase C (PKC) inhibited both P-glycoprotein phosphorylation and activity. However, site-directed mutagenesis of all phosphorylatable residues did not alter the drug resistance. The present work shows that PKC effectors are able to bind directly to multidrug transporters, from either cancer cells (mouse P-glycoprotein), yeast (Saccharomyces cerevisiae Pdr5p), or protozoan parasite (Leishmania tropica ltmdr1), and to inhibit their energy-dependent drug-efflux activity. The binding of staurosporine and derivatives such as CGP 41251 is prevented by preincubation with ATP, suggesting at least partial interaction at the ATP-binding site. In contrast, more hydrophobic compounds such as calphostin C and CGP 42700 bind outside the ATP-binding site and strongly interfere with drug interaction. A direct correlation is obtained between the efficiencies of PKC effectors to inhibit energy-dependent interaction of rhodamine 6G with yeast Pdr5p, to promote intracellular drug accumulation in various multidrug resistant cells, and to chemosensitize growth of resistant cells. The noncompetitive inhibition by PKC effectors of rhodamine 6G interaction with Pdr5p suggests that the binding might interfere with signal transduction between nucleotide hydrolysis and drug interaction. The overall results indicate that the multidrug transporters from different species display common features for interaction with PKC inhibitors. The hydrophobic derivative of staurosporine, CGP 42700, constitutes a potentially powerful modulator of P-glycoprotein-mediated multidrug resistance.
authors.affiliation: Laboratoire des Protéines de Résistance aux Agents Chimiothérapeutiques, Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS/Université Claude Bernard-Lyon I, Lyon, France.
authors.forename: G
authors.initials: G
authors.lastname: Conseil
authors.forename: J M
authors.initials: JM
authors.lastname: Perez-Victoria
authors.forename: J M
authors.initials: JM
authors.lastname: Jault
authors.forename: F
authors.initials: F
authors.lastname: Gamarro
authors.forename: A
authors.initials: A
authors.lastname: Goffeau
authors.forename: J
authors.initials: J
authors.lastname: Hofmann
authors.forename: A
authors.initials: A
authors.lastname: Di Pietro
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology; D001665:Binding Sites; D003600:Cytosol / Q000378:metabolism; D003630:Daunorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D004734:Energy Metabolism / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D007895:Leishmania tropica / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051379:Mice; D009281:Naphthalenes / Q000378:metabolism / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D011755:Pyrophosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D012235:Rhodamines / Q000037:antagonists & inhibitors / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D019311:Staurosporine / Q000378:metabolism / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D000981:Antiprotozoal Agents; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D005656:Fungal Proteins; D008565:Membrane Proteins; D009281:Naphthalenes; C092438:PDR5 protein, S cerevisiae; D015800:Protozoan Proteins; D012235:Rhodamines; D029701:Saccharomyces cerevisiae Proteins; C026188:rhodamine 6G; D011493:Protein Kinase C; D011755:Pyrophosphatases; C023278:uridine triphosphatase; D019311:Staurosporine; C058819:calphostin C; D003630:Daunorubicin