title: Down-regulation and altered localization of gamma-catenin in cisplatin-resistant adenocarcinoma cells.
abstract: Resistance to cisplatin, one of the most widely used anticancer chemotherapeutic agents, is a major clinical problem. There is no effective way to predict development of cisplatin resistance in cancers. As determined by reverse transcription-polymerase chain reaction and Western blotting, the expression of gamma-catenin, an adherens junction protein, was decreased in KB-CP20 and 7404-CP20 cells compared with parental-sensitive cells. Short-term treatment with cisplatin of the parental cells resulted in proteolysis of gamma-catenin as evaluated in membrane pellet preparations, and the extent of cleavage increased as cisplatin concentration was raised from 1 to 5 microg/ml during 1 h of treatment. Uncleaved cytoplasmic gamma-catenin increased under the same conditions. These biochemical results were supported by confocal microscopy, which showed a loss of gamma-catenin from adherens plaques after cisplatin treatment. Cleavage of gamma-catenin was specific to cisplatin treatment in that cleavage did not occur after treatment with doxorubicin and cytosine arabinoside. Pretreatment of KB and 7404 cells with cisplatin for 1 h resulted in reduced uptake of [(14)C]carboplatin, suggesting that the biochemical changes induced by cisplatin treatment, including cleavage of gamma-catenin, could affect the ability of cells to internalize platinum compounds. Cells transfected with the gamma-catenin gene are sensitive to cisplatin compared with cells transfected with a control vector. Our data suggest that proteolysis and altered localization of gamma-catenin are early markers for the response of cells to cisplatin, and reduced levels of gamma-catenin in resistant cells may indicate an important role for gamma-catenin in mediating or modulating the toxicity of cisplatin in cancer cells.
authors.affiliation: Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Room 1A09, Bethesda, MD 20892-4254, USA.
authors.forename: Xing-Jie
authors.initials: XJ
authors.lastname: Liang
authors.forename: Ding-Wu
authors.initials: DW
authors.lastname: Shen
authors.forename: Michael M
authors.initials: MM
authors.lastname: Gottesman
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000970:Antineoplastic Agents / Q000493:pharmacokinetics / Q000494:pharmacology; D002250:Carbon Radioisotopes; D016190:Carboplatin / Q000493:pharmacokinetics; D002945:Cisplatin / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D051180:Desmoplakins; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D006801:Humans; D007624:KB Cells; D008297:Male; D008727:Methotrexate / Q000493:pharmacokinetics; D014162:Transfection; D014316:Tritium; D014407:Tumor Cells, Cultured; D051185:gamma Catenin
chemical_list: D000970:Antineoplastic Agents; D002250:Carbon Radioisotopes; D003598:Cytoskeletal Proteins; D051180:Desmoplakins; C495292:JUP protein, human; D051185:gamma Catenin; D014316:Tritium; D016190:Carboplatin; D002945:Cisplatin; D008727:Methotrexate