title: Transmembrane inhibitors of P-glycoprotein, an ABC transporter.
abstract: Drug resistance mediated by ABC transporters such as P-glycoprotein (P-gp) continues to be a major impediment to effective cancer chemotherapy. We have developed a panel of highly specific peptide inhibitors of P-gp based on the structure of the transmembrane domains of the transporter. These peptides are thought to exert their inhibitory action by disrupting the proper assembly of P-gp. A novel 96-well-plate assay based on the efflux of fluorescent P-gp substrate DiOC2 (3-ethyl-2-[3-(3-ethyl-2(3H)-benzoxazolylidene)-1-propenyl]benzoxazolium iodide) was developed and used for structure-functional characterization of transporter inhibitors. The studies strongly suggest that potent and selective inhibitors of ABC transporters can now be developed solely on the basis of the primary structures of the target proteins. The inhibition of P-gp with transmembrane peptides was shown to be chirality-independent. A 25-residue long retroinverso D-analogue of transmembrane domain 5 inhibited the efflux of the fluorescent P-gp substrate with an IC50 of 500 nM. Transmembrane peptides effectively sensitized resistant cancer cells to doxorubicin in vitro without demonstrating any cell toxicity of their own. The newly synthesized P-gp antagonists appear to be promising nontoxic drug resistance inhibitors that merit further development.
authors.affiliation: Molecular Aspects of Drug Design Section, Structural Biophysics Laboratory, NCI-Frederick, P.O. Box B, Frederick, Maryland 21702, USA. tarasova@ncifcrf.gov
authors.forename: Nadya I
authors.initials: NI
authors.lastname: Tarasova
authors.forename: Rishi
authors.initials: R
authors.lastname: Seth
authors.forename: Sergey G
authors.initials: SG
authors.lastname: Tarasov
authors.forename: Teresa
authors.initials: T
authors.lastname: Kosakowska-Cholody
authors.forename: Christine A
authors.initials: CA
authors.lastname: Hrycyna
authors.forename: Michael M
authors.initials: MM
authors.lastname: Gottesman
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Michejda
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004354:Drug Screening Assays, Antitumor; D004591:Electrophoresis, Polyacrylamide Gel; D005453:Fluorescence; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D010455:Peptides