title: Role of P-glycoprotein in human natural killer-like cell line-mediated cytotoxicity.
abstract: Natural killer (NK) cells express the highest amount of P-glycoprotein (Pgp), a product of the multidrug resistance (MDR) 1 gene, among lymphoid cells, and our previous studies demonstrated that Pgp is required for NK cell-mediated cytotoxicity. In this study we examined the role of Pgp in NK cell-mediated cytotoxicity using a human NK-like cell line, i.e., YTN cells and two MDR reversing agents, nicardipine and its structural analog, AHC-93. These two agents inhibited the Pgp function (rhodamine-123 excretion) as well as cell-mediated cytotoxicity, confirming that Pgp is critical for NK cell-mediated cytotoxicity. As revealed by video-rate ultraviolet laser-scanning confocal microscopy, AHC-93 did not inhibit the increase in the intracellular calcium concentration upon binding to target cells, whereas nicardipine did, as reported previously. These two reagents relocated acridine orange dye from lysosomes to the cytoplasm at concentrations similar to those required for the inhibition of cell-mediated cytotoxicity. These results suggest that Pgp is directly or indirectly involved in pH regulation in lysosomes, but not in calcium homeostasis.
authors.affiliation: Faculty of Science, Toho University, 2-2-1 Miyama, Chiba, 274, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: Y
authors.initials: Y
authors.lastname: Misawa
authors.forename: N
authors.initials: N
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Kawanishi
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
authors.forename: K
authors.initials: K
authors.lastname: Shigenobu
authors.forename: Y
authors.initials: Y
authors.lastname: Kobayashi
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000276:immunology*; D000165:Acridine Orange / Q000493:pharmacokinetics; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003584:Cytological Techniques; D003593:Cytoplasm / Q000378:metabolism; D018432:Drug Resistance, Multiple / Q000276:immunology*; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007694:Killer Cells, Natural / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods; D009529:Nicardipine / Q000494:pharmacology; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma; D011720:Pyrazoles / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D020112:Rhodamine 123 / Q000493:pharmacokinetics; D013945:Thymoma; D014407:Tumor Cells, Cultured
chemical_list: C402656:AHC 93; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002121:Calcium Channel Blockers; D005456:Fluorescent Dyes; D011720:Pyrazoles; D011725:Pyridines; D020112:Rhodamine 123; D009529:Nicardipine; D000165:Acridine Orange; D002118:Calcium