title: Overexpression of a M(r) 110,000 vesicular protein in non-P-glycoprotein-mediated multidrug resistance.
abstract: A M(r) 110,000 protein (p110) is overexpressed in P-glycoprotein-negative multidrug-resistant tumor cell lines of different histogenetic origins. These cell lines show an ATP-dependent drug accumulation defect, suggesting the presence of drug transporter molecules different from P-glycoprotein. Immunohistochemical staining with a p110-specific monoclonal antibody (LRP-56) showed that, like P-glycoprotein, the molecule has a high expression in normal epithelial cells and tissues chronically exposed to xenobiotics and potentially toxic agents, such as bronchial cells, cells lining the intestines, and kidney tubules. Staining of LRP-56 is primarily cytoplasmic, in a coarsely granular fashion, indicating that it reacts with a molecule closely associated with vesicular/lysosomal structures. Involvement of p110 in the energy-dependent drug transport process present in the cell lines is unknown.
authors.affiliation: Department of Pathology, Free University Hospital, Amsterdam, The Netherlands.
authors.forename: R J
authors.initials: RJ
authors.lastname: Scheper
authors.forename: H J
authors.initials: HJ
authors.lastname: Broxterman
authors.forename: G L
authors.initials: GL
authors.lastname: Scheffer
authors.forename: P
authors.initials: P
authors.lastname: Kaaijk
authors.forename: W S
authors.initials: WS
authors.lastname: Dalton
authors.forename: T H
authors.initials: TH
authors.lastname: van Heijningen
authors.forename: C K
authors.initials: CK
authors.lastname: van Kalken
authors.forename: M L
authors.initials: ML
authors.lastname: Slovak
authors.forename: E G
authors.initials: EG
authors.lastname: de Vries
authors.forename: P
authors.initials: P
authors.lastname: van der Valk
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000818:Animals; D000911:Antibodies, Monoclonal; D004351:Drug Resistance / Q000235:genetics; D006801:Humans; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins / Q000032:analysis; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000032:analysis*; D013194:Staining and Labeling; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins