title: Correlation between reversing of multidrug resistance and inhibiting of [3H]azidopine photolabeling of P-glycoprotein by newly synthesized dihydropyridine analogues in a human cell line.
abstract: Ten synthetic dihydropyridine analogues were investigated for their ability to reverse drug resistance in a multidrug-resistant human carcinoma cell line, KB-Cl. Four dihydropyridine analogues completely reversed the resistance, three lowered the resistance, and three had little effect. The radioactive photoactive dihydropyridine calcium channel blocker, [3H]azidopine, photolabels P-glycoprotein in membrane vesicles from KB-Cl cells. This photolabeling was almost completely inhibited by excess dihydropyridine analogues that reversed or lowered drug resistance. In contrast, the labeling was not significantly inhibited by analogues that do not reverse resistance. Among other reversing agents, cepharanthine and reserpine inhibited the [3H]azidopine photolabeling, but thioridazine did not. N-Solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine slightly inhibited the labeling at 100 microM. An anticancer agent, vinblastine, also inhibited the labeling. The correlation between the reversing of the drug resistance and the inhibition of the [3H]azidopine photolabeling of P-glycoprotein by dihydropyridine analogues suggests a role for P-glycoprotein in multidrug resistance and also the reversing of the resistance by dihydropyridine analogues.
authors.affiliation: Department of Cancer Chemotherapy, Institute of Cancer Research, Faculty of Medicine, Kagoshima University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kamiwatari
authors.forename: Y
authors.initials: Y
authors.lastname: Nagata
authors.forename: H
authors.initials: H
authors.lastname: Kikuchi
authors.forename: A
authors.initials: A
authors.lastname: Yoshimura
authors.forename: T
authors.initials: T
authors.lastname: Sumizawa
authors.forename: N
authors.initials: N
authors.lastname: Shudo
authors.forename: R
authors.initials: R
authors.lastname: Sakoda
authors.forename: K
authors.initials: K
authors.lastname: Seto
authors.forename: S
authors.initials: S
authors.lastname: Akiyama
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000345:Affinity Labels / Q000378:metabolism*; D001386:Azides / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D004095:Dihydropyridines / Q000378:metabolism* / Q000494:pharmacology*; D004351:Drug Resistance; D006801:Humans; D007624:KB Cells; D008562:Membrane Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D013329:Structure-Activity Relationship; D014750:Vincristine / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000345:Affinity Labels; D001386:Azides; D004095:Dihydropyridines; D008562:Membrane Glycoproteins; D014750:Vincristine; C041130:azidopine