title: The multidrug resistance protein ABCC1 drug-binding domains show selective sensitivity to mild detergents.
abstract: The multidrug resistance protein (ABCC1 or MRP1) causes resistance to multiple drugs through reduced drug accumulation. We have previously demonstrated direct interaction between MRP1 and unmodified drugs using photoreactive drug analogues. In this study, we describe the use of [125I]iodoaryl azido-rhodamine123 (IAARh123)-a photoactive drug analogue of rhodamine 123, to study the effects of mild detergents and denaturing agents on MRP1-drug binding in membrane vesicles prepared from HeLa cells transfected with the MRP1 cDNA. Our results show that the zwitterionic detergent CHAPS and a nonionic detergent Brij35 inhibited the photolabeling of MRP1 with IAARh123. Sodium deoxycholate (SDC) and octyl-beta-glucoside (OG), structurally similar to CHAPS and Brij35 and disrupting the lipid bilayer, showed a modest increase of MRP1 photolabeling with IAARh123. Proteolytic digestion of IAARh123 photolabeled MRP1 labeled in the presence or absence of various detergents (CHAPS, SDC, or OG) revealed identical photolabeled peptides. Consistent with the drug-binding results, non-toxic concentrations of CHAPS and Brij35 reversed vincristine and etoposide (VP16) toxicity in MRP1 expressing cells. Taken together, the results of this study show that MRP1-drug interaction can occur outside the lipid bilayer environment. However, this interaction is inhibited with certain mild detergents.
authors.affiliation: Institute of Parasitology, McGill University, Macdonald Campus, 21,111 Lakeshore Road, Ste Anne de Bellevue, Que., Canada H9X 3V9.
authors.forename: Omar
authors.initials: O
authors.lastname: Alqawi
authors.forename: Elias
authors.initials: E
authors.lastname: Georges
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001665:Binding Sites; D002470:Cell Survival / Q000187:drug effects; D002793:Cholic Acids / Q000737:chemistry / Q000494:pharmacology; D003902:Detergents / Q000737:chemistry / Q000494:pharmacology*; D004347:Drug Interactions; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005047:Etoposide / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008051:Lipid Bilayers; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000737:chemistry* / Q000378:metabolism*; D019920:Photoaffinity Labels; D000077423:Polidocanol; D011092:Polyethylene Glycols / Q000737:chemistry / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D020112:Rhodamine 123; D014750:Vincristine / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D002793:Cholic Acids; D003902:Detergents; D005047:Etoposide; D008051:Lipid Bilayers; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D019920:Photoaffinity Labels; D000077423:Polidocanol; D011092:Polyethylene Glycols; D020112:Rhodamine 123; D014750:Vincristine; C028213:3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate; C421109:multidrug resistance-associated protein 1