title: A repurposing strategy identifies novel synergistic inhibitors of Plasmodium falciparum heat shock protein 90.
abstract: Malaria is responsible for 3 million deaths annually. Antimalarial drug resistance is widespread, and few novel, well-defined targets exist. A robotic high throughput screen (HTS) was performed using 4000 small molecules from a natural compound (Spectrum), pharmacologically active (Lopac), and Food and Drug Administration (FDA) approved drug library (Prestwick) for competitive inhibition of the ATP-binding (GHKL) domain of Plasmodium falciparum (Pf) Hsp90, a highly conserved chaperone. Hits were further screened for specificity based on differential inhibition of PfHsp90 in comparison to human (Hs) Hsp90. PfHsp90-specific inhibitors showed 50% inhibitory concentrations (IC(50)) in the nanomolar range when tested using a cell-based antimalarial validation assay. Three hits, identified as selective PfHsp90 inhibitors in the HTS, also demonstrated synergistic activity in the presence of the known antimalarial drug chloroquine. These data support PfHsp90 as a specific antimalarial target with potential for synergy with known antimalarials.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada.
authors.forename: Dea
authors.initials: D
authors.lastname: Shahinas
authors.forename: Michael
authors.initials: M
authors.lastname: Liang
authors.forename: Alessandro
authors.initials: A
authors.lastname: Datti
authors.forename: Dylan R
authors.initials: DR
authors.lastname: Pillai
mesh_terms: D000255:Adenosine Triphosphate; D000962:Antimalarials / Q000737:chemistry* / Q000494:pharmacology; D001665:Binding Sites; D001667:Binding, Competitive; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D004357:Drug Synergism; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D021261:Parasitic Sensitivity Tests; D010963:Plasmodium falciparum / Q000187:drug effects*; D054852:Small Molecule Libraries; D013379:Substrate Specificity
chemical_list: D000962:Antimalarials; D018841:HSP90 Heat-Shock Proteins; D054852:Small Molecule Libraries; D000255:Adenosine Triphosphate