title: Inhibition of multidrug resistance by adamantylgb3, a globotriaosylceramide analog.
abstract: Multidrug resistance (MDR) via the ABC drug transporter (ABCB1), P-glycoprotein (P-gp/MDR1) overexpression, is a major obstacle in cancer chemotherapy. Many inhibitors reverse MDR but, like cyclosporin A (CsA), have significant toxicities. MDR1 is also a translocase that flips glucosylceramide inside the Golgi to enhance neutral glycosphingolipid (GSL) synthesis. We observed partial MDR1/globotriaosylceramide (Gb3) cell surface co-localization, and GSL removal depleted cell surface MDR1. MDR1 may therefore interact with GSLs. AdamantylGb3, a water-soluble Gb3 mimic, but not other GSL analogs, reversed MDR1-MDCK cell drug resistance. Cell surface MDR1 was up-regulated 1 h after treatment with CsA or adaGb3, but at 72 h, cell surface expression was lost. Intracellular MDR1 accumulated throughout, suggesting long term defects in plasma membrane MDR1 trafficking. AdaGb3 or CsA rapidly reduced rhodamine 123 cellular efflux. MDR1 also mediates gastrointestinal epithelial drug efflux, restricting oral bioavailability. Vinblastine apical-to-basal transport in polarized human intestinal C2BBe1 cells was significantly increased when adaGb3 was added to both sides, or to the apical side only, comparable with verapamil, a standard MDR1 inhibitor. Disulfide cross-linking of mutant MDR1s showed no binding of adaGb3 to the MDR1 verapamil/cyclosporin-binding site between surface proximal helices of transmembrane segments (TM) 6 and TM7, but rather to an adjacent site nearer the center of TM6 and the TM7 extracellular face, i.e. close to the bilayer leaflet interface. Verotoxin-mediated Gb3 endocytosis also up-regulated total MDR1 and inhibited drug efflux. Thus, a functional interplay between membrane Gb3 and MDR1 provides a more physiologically based approach to MDR1 regulation to increase the bioavailability of chemotherapeutic drugs.
authors.affiliation: Division of Molecular Structure and Function, Department of Pediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.
authors.forename: María Fabiana
authors.initials: MF
authors.lastname: De Rosa
authors.forename: Cameron
authors.initials: C
authors.lastname: Ackerley
authors.forename: Bernice
authors.initials: B
authors.lastname: Wang
authors.forename: Shinya
authors.initials: S
authors.lastname: Ito
authors.forename: David M
authors.initials: DM
authors.lastname: Clarke
authors.forename: Clifford
authors.initials: C
authors.lastname: Lingwood
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000218:Adamantane / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D001682:Biological Availability; D018938:Caco-2 Cells; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D016764:Cell Polarity / Q000187:drug effects / Q000235:genetics; D016572:Cyclosporine / Q000494:pharmacology; D004285:Dogs; D018432:Drug Resistance, Multiple / Q000187:drug effects* / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics; D004705:Endocytosis / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000494:pharmacology; D006056:Golgi Apparatus / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D017433:Protein Structure, Secondary / Q000235:genetics; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D020112:Rhodamine 123 / Q000494:pharmacology; D022603:Shiga Toxins / Q000494:pharmacology; D013997:Time Factors; D014281:Trihexosylceramides / Q000096:biosynthesis / Q000493:pharmacokinetics / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D014700:Verapamil / Q000494:pharmacology; D014747:Vinblastine / Q000494:pharmacology
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000972:Antineoplastic Agents, Phytogenic; D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D011500:Protein Synthesis Inhibitors; D022603:Shiga Toxins; D014281:Trihexosylceramides; C514155:adamantyl-globotriaosyl ceramide; D020112:Rhodamine 123; D014747:Vinblastine; C018549:globotriaosylceramide; D016572:Cyclosporine; D014700:Verapamil; D000218:Adamantane