title: Measurement of P-glycoprotein expression in multidrug-resistant human neuroblastoma cell lines using self-competitive binding assay.
abstract: To date, all reported measurements of multidrug resistance have been semiquantitative. The purpose of the present study is to establish and validate the self-competitive binding assay technique utilizing monoclonal antibody for quantitative estimation of multidrug resistance in tumor cells. This technique is used for P-glycoprotein concentration measurement in BE(2)-C human neuroblastoma cell line and its sublines with primary resistance to colchicine and actinomycin D. Monoclonal antibody MRK-16 was used in this study. It was labeled with iodine-125 (125I) to trace the concentration of antibody-antigen complexes. The binding data were obtained by varying the concentration of the unlabeled antibody. The results were fitted to a model equation to estimate the number of binding sites and antibody-antigen dissociation constant. The P-glycoprotein concentration was significantly higher in the resistant sublines than in the sensitive line. The highest levels were achieved in actinomycin D-resistant cells: 2.1 x 10(6) binding sites/cell versus 5.4 x 10(4) binding sites/cell in the sensitive cells. The consistency of the results was verified by repeating the study three times for each cell line. The binding assay results were confirmed by Western blot experiments performed on the same cell lines.
authors.affiliation: Nuclear Medicine Research Laboratory, Memorial Sloan Kettering Cancer Center, New York, New York 10021, USA.
authors.forename: A
authors.initials: A
authors.lastname: Levchenko
authors.forename: B M
authors.initials: BM
authors.lastname: Mehta
authors.forename: B A
authors.initials: BA
authors.lastname: Spengler
authors.forename: A A
authors.initials: AA
authors.lastname: Narkar
authors.forename: R
authors.initials: R
authors.lastname: Fonti
authors.forename: J L
authors.initials: JL
authors.lastname: Biedler
authors.forename: T
authors.initials: T
authors.lastname: Tsuruo
authors.forename: S M
authors.initials: SM
authors.lastname: Larson
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis*; D000911:Antibodies, Monoclonal; D001667:Binding, Competitive; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D000939:Epitopes; D006801:Humans; D016014:Linear Models; D009363:Neoplasm Proteins / Q000032:analysis*; D009447:Neuroblastoma / Q000737:chemistry*; D015203:Reproducibility of Results; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D000939:Epitopes; D009363:Neoplasm Proteins