title: Characterization of the ATP-dependent LTC4 transporter in cisplatin-resistant human KB cells.
abstract: An active efflux pump for cis-diamminedichloroplatinum(II) (cisplatin) has been identified in cisplatin-resistant KCP-4 cells isolated from human epidermoid carcinoma KB-3-1 cells. The adenosine triphosphate(ATP)-dependent transport of leukotriene C4 (LTC4), an endogenous substrate for the glutathione S-conjugate export pump(GS-X pump), has been found in membrane vesicles prepared from KCP-4 cells. Multidrug resistance-associated protein (MRP) has also been identified as an ATP-dependent LTC4 transporter. To examine whether the GS-X pump expressed in KCP-4 cells in MRP, we investigated the expression of MRP in KCP-4 cells and compared the LTC4 transporting activity of GS-X pump expressed in KCP-4 cells with that of MRP. The level of MRP gene expression in KCP-4 cells was low and similar to that in KB-3-1 cells. MRP was not detected in membrane vesicles prepared from KB-3-1 and KCP-4 cells by immunoblot analysis. The ATP-dependent transport of LTC4 in KCP-4 and C-A120 vesicles showed saturable kinetics with an apparent Km of 0.18 microM and 0.25 microM, respectively. [3H]LTC4 transport in KCP-4 vesicles was more inhibited by 2,4-dinitrophenyl-S-glutathione(DNP-SG), bis-(glutathionato)-platinum(II) (GS-platinum) complex and glutathione disulfide(GS-SG) and less by LTD4 compared with that in C-A120 vesicles. The character of the LTC4 transporter expressed in KCP-4 vesicles is similar but not identical to that of MRP. Our results suggest that a glutathione S-conjugate export pump which is different from MRP exists in cisplatin-resistant KCP-4 cells.
authors.affiliation: Institute for Cancer Research, Faculty of Medicine, Kagoshima University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Chuman
authors.forename: Z S
authors.initials: ZS
authors.lastname: Chen
authors.forename: T
authors.initials: T
authors.lastname: Sumizawa
authors.forename: T
authors.initials: T
authors.lastname: Furukawa
authors.forename: M
authors.initials: M
authors.lastname: Haraguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Takebayashi
authors.forename: K
authors.initials: K
authors.lastname: Niwa
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: T
authors.initials: T
authors.lastname: Aikou
authors.forename: S
authors.initials: S
authors.lastname: Akiyama
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D017997:Leukotriene C4 / Q000378:metabolism*; D008969:Molecular Sequence Data; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009994:Osmolar Concentration; D012333:RNA, Messenger / Q000235:genetics; D014316:Tritium; D014407:Tumor Cells, Cultured; D014700:Verapamil / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D000255:Adenosine Triphosphate; D002945:Cisplatin; D005978:Glutathione; D017997:Leukotriene C4; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; D014316:Tritium; D014700:Verapamil