title: The molecular interaction of a copper chelate with human P-glycoprotein.
abstract: One of the major reasons for multidrug resistance (MDR) in cancer is the overexpression of P-glycoprotein (P-gp, ABCB1), a drug efflux pump. A novel copper complex, namely, copper (II) N-(2-hydroxyacetophenone) glycinate (CuNG) previously synthesized and characterized by the authors had been tested in this study. In a cell-based assay system with human MDR1 cDNA overexpressed mouse fibroblast NIH MDR1-G185 cell line, we demonstrated that this metal complex can directly interact with this transporter. As CuNG increased cellular accumulation of doxorubicin in P-gp-expressing cells, we presumed that of CuNG may be potential to reverse P-gp-mediated drug resistance probably by lowering the P-gp expression at the protein as well as mRNA level. Interestingly, our studies on UIC2 (a conformation sensitive monoclonal antibody) binding assay indicated the direct interaction of CuNG with P-gp. However, CuNG did not compete for the substrate binding as photoaffinity labeling of P-gp with a substrate analog [(125)I] iodoarylazidoprazosin ([(125)I] IAAP) showed approximately twofold increase in [(125)I] IAAP binding in presence of CuNG. In vitro study showed that CuNG significantly stimulated P-gp-specific ATPase activity in isolated membrane preparations from NIH MDR1-G185 cells. This result further confirmed the CuNG-P-gp direct interaction. This study also demonstrated that CuNG has a drug interaction site different from verapamil-, vinblastine- and progesterone-binding sites on P-gp. Taken together, this is the first report of molecular interaction of any Schiff's base metal chelate CuNG with human P-gp. This information may be useful to design more efficacious nontoxic metal-based drugs as MDR-reversing agents.
authors.affiliation: Department of In Vitro Carcinogenesis and Cellular Chemotherapy, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata 700 026, India.
authors.forename: Ruma Dey
authors.initials: RD
authors.lastname: Ghosh
authors.forename: Paramita
authors.initials: P
authors.lastname: Chakraborty
authors.forename: Kaushik
authors.initials: K
authors.lastname: Banerjee
authors.forename: Arghya
authors.initials: A
authors.lastname: Adhikary
authors.forename: Avijit
authors.initials: A
authors.lastname: Sarkar
authors.forename: Mitali
authors.initials: M
authors.lastname: Chatterjee
authors.forename: Tanya
authors.initials: T
authors.lastname: Das
authors.forename: Soumitra Kumar
authors.initials: SK
authors.lastname: Choudhuri
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002614:Chelating Agents / Q000737:chemistry / Q000494:pharmacology*; D003300:Copper; D004317:Doxorubicin / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D005998:Glycine / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D051379:Mice; D009942:Organometallic Compounds / Q000737:chemistry / Q000494:pharmacology
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002614:Chelating Agents; D009942:Organometallic Compounds; C515714:copper (N-2-hydroxyacetophenone)glycinate; D003300:Copper; D004317:Doxorubicin; D000251:Adenosine Triphosphatases; D005998:Glycine