title: Functional interactions of Cu-ATPase ATP7B with cisplatin and the role of ATP7B in the resistance of cells to the drug.
abstract: Cisplatin is a widely used chemotherapeutic agent for treatment of ovarian, testicular, lung, and stomach cancers. The initial response to the drug is robust; however, tumor cells commonly develop resistance to cisplatin, which complicates treatment. Recently, overexpression of the Cu-ATPase ATP7B in ovary cells was linked to the increased cellular resistance to cisplatin; and the role for Cu-ATPases in the export of cisplatin from cells was proposed. Our results support functional interactions between cisplatin and ATP7B but argue against the active transport through the copper translocation pathway as a mechanism of drug resistance. In hepatocytes, we observed no correlation between the levels of endogenous ATP7B and the resistance of cells to cisplatin. Unlike copper, cisplatin does not induce trafficking of ATP7B in hepatoma cells, neither does it compete with copper in a transport assay. However, cisplatin binds to ATP7B and stimulates catalytic phosphorylation with EC(50) similar to that of copper. Mutations of the first five N-terminal copper-binding sites of ATP7B do not inhibit the cisplatin-induced phosphorylation of ATP7B. In contrast, the deletion of the first four copper-binding sites abolishes the effect of cisplatin on the ATP7B activity. Thus, cisplatin binding to ATP7B and/or general changes in cellular copper homeostasis are likely contributors to the increased resistance to the drug. The link between changes in copper homeostasis and cisplatin resistance was confirmed by treating the Huh7 cells with copper chelator and increasing their resistance to cisplatin.cisplatin.
authors.affiliation: Department of Medicine II and Department of Biochemistry, University of Leipzig, 04103 Leipzig, Germany.
authors.forename: Karoline
authors.initials: K
authors.lastname: Leonhardt
authors.forename: Rolf
authors.initials: R
authors.lastname: Gebhardt
authors.forename: Joachim
authors.initials: J
authors.lastname: Mössner
authors.forename: Svetlana
authors.initials: S
authors.lastname: Lutsenko
authors.forename: Dominik
authors.initials: D
authors.lastname: Huster
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001665:Binding Sites / Q000235:genetics; D001692:Biological Transport / Q000187:drug effects / Q000235:genetics; D002384:Catalysis / Q000187:drug effects; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002614:Chelating Agents / Q000494:pharmacology / Q000627:therapeutic use; D002945:Cisplatin / Q000494:pharmacology* / Q000627:therapeutic use; D003300:Copper / Q000378:metabolism*; D000073840:Copper-Transporting ATPases; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics; D022781:Hepatocytes / Q000201:enzymology; D006706:Homeostasis / Q000187:drug effects / Q000235:genetics; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009369:Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D011485:Protein Binding
chemical_list: D000970:Antineoplastic Agents; D027682:Cation Transport Proteins; D002614:Chelating Agents; D003300:Copper; D000251:Adenosine Triphosphatases; C000612464:ATP7B protein, human; D000073840:Copper-Transporting ATPases; D002945:Cisplatin