title: Reversing ABCB1-mediated multi-drug resistance from within cells using translocating immune conjugates.
abstract: Multi-drug resistance (MDR) is still a major cause of the eventual failure of chemotherapy in cancer treatment. Different approaches have been taken to render these cells drug sensitive. Here, we attempted sensitizing drug-resistant cells from within, using a translocating immune conjugate approach. To that effect, a monoclonal antibody, C219, directed against the intracellular ATP-binding site of the membrane-anchored MDR transporter ABCB1 [P-glycoprotein (P-gp), MDR1], was conjugated to human immunodeficiency virus [HIV(37-72)Tat] translocator peptide through a disulfide bridge. Fluorescence-labelled IgG-Tat conjugates accumulated in drug resistant Chinese hamster ovary (CHO) cells within less than 20 min. Preincubation with C219-S-S-(37-72)Tat conjugate augmented calcein accumulation in drug-resistant CHO and mouse lymphoma cells, indicating reduction in ABCB1 transporter activity. A thioether conjugate C219-S-(37-72)Tat was ineffective, as were disulfide and thioether conjugates of an irrelevant antibody. Furthermore, in the presence of C219-S-S-(37-72)Tat, drug resistant cells were sensitized to colchicine and doxorubicin. Taken together, these findings demonstrate, as proof of principle, a novel approach for the reversal of MDR from within cells, by delivery of translocating immune conjugates as sensitizing agents towards chemotherapy.
authors.affiliation: Institute of Toxicology, Medical School Hannover, Hannover, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Wellhöner
authors.forename: Aryeh
authors.initials: A
authors.lastname: Weiss
authors.forename: Axel
authors.initials: A
authors.lastname: Schulz
authors.forename: Knut
authors.initials: K
authors.lastname: Adermann
authors.forename: Ori
authors.initials: O
authors.lastname: Braitbard
authors.forename: Allan
authors.initials: A
authors.lastname: Bar-Sinai
authors.forename: Jacob
authors.initials: J
authors.lastname: Hochman
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000276:immunology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D016466:CHO Cells; D045744:Cell Line, Tumor; D003078:Colchicine / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D006801:Humans; D018796:Immunoconjugates; D007074:Immunoglobulin G / Q000276:immunology*; D008223:Lymphoma / Q000188:drug therapy / Q000473:pathology; D051379:Mice; D013997:Time Factors; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000276:immunology*
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D018796:Immunoconjugates; D007074:Immunoglobulin G; D054322:tat Gene Products, Human Immunodeficiency Virus; D004317:Doxorubicin; D000255:Adenosine Triphosphate; D003078:Colchicine