title: In silico screening for inhibitors of p-glycoprotein that target the nucleotide binding domains.
abstract: Multidrug resistances and the failure of chemotherapies are often caused by the expression or overexpression of ATP-binding cassette transporter proteins such as the multidrug resistance protein, P-glycoprotein (P-gp). P-gp is expressed in the plasma membrane of many cell types and protects cells from accumulation of toxins. P-gp uses ATP hydrolysis to catalyze the transport of a broad range of mostly hydrophobic compounds across the plasma membrane and out of the cell. During cancer chemotherapy, the administration of therapeutics often selects for cells which overexpress P-gp, thereby creating populations of cancer cells resistant to a variety of chemically unrelated chemotherapeutics. The present study describes extremely high-throughput, massively parallel in silico ligand docking studies aimed at identifying reversible inhibitors of ATP hydrolysis that target the nucleotide-binding domains of P-gp. We used a structural model of human P-gp that we obtained from molecular dynamics experiments as the protein target for ligand docking. We employed a novel approach of subtractive docking experiments that identified ligands that bound predominantly to the nucleotide-binding domains but not the drug-binding domains of P-gp. Four compounds were found that inhibit ATP hydrolysis by P-gp. Using electron spin resonance spectroscopy, we showed that at least three of these compounds affected nucleotide binding to the transporter. These studies represent a successful proof of principle demonstrating the potential of targeted approaches for identifying specific inhibitors of P-gp.
authors.affiliation: Department of Biological Sciences, the Center for Drug Discovery, Design and Delivery, and the Center for Scientific Computing, Southern Methodist University, Dallas, Texas.
authors.forename: Frances K
authors.initials: FK
authors.lastname: Brewer
authors.affiliation: Department of Biological Sciences, the Center for Drug Discovery, Design and Delivery, and the Center for Scientific Computing, Southern Methodist University, Dallas, Texas.
authors.forename: Courtney A
authors.initials: CA
authors.lastname: Follit
authors.affiliation: Department of Biological Sciences, the Center for Drug Discovery, Design and Delivery, and the Center for Scientific Computing, Southern Methodist University, Dallas, Texas.
authors.forename: Pia D
authors.initials: PD
authors.lastname: Vogel
authors.affiliation: Department of Biological Sciences, the Center for Drug Discovery, Design and Delivery, and the Center for Scientific Computing, Southern Methodist University, Dallas, Texas jwise@smu.edu.
authors.forename: John G
authors.initials: JG
authors.lastname: Wise
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D006868:Hydrolysis; D062105:Molecular Docking Simulation; D009711:Nucleotides / Q000378:metabolism*; D017434:Protein Structure, Tertiary
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D009711:Nucleotides; D000255:Adenosine Triphosphate