PT - JOURNAL ARTICLE AU - Frances K Brewer AU - Courtney A Follit AU - Pia D Vogel AU - John G Wise TI - <em>In silico</em> Screening for Inhibitors of P-Glycoprotein that Target the Nucleotide Binding Domains AID - 10.1124/mol.114.095414 DP - 2014 Sep 30 TA - Molecular Pharmacology PG - mol.114.095414 4099 - http://molpharm.aspetjournals.org/content/early/2014/09/30/mol.114.095414.short 4100 - http://molpharm.aspetjournals.org/content/early/2014/09/30/mol.114.095414.full AB - Multidrug resistances and the failure of chemotherapies are often caused by the expression or overexpression of ABC-transporter proteins like the MDR1 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 3 of these compounds affected nucleotide binding to the transporter. These studies represent a successful proof-of-principle demonstrating to potential of targeted approaches to identifying specific inhibitors of P-gp.