title: Hsp90 inhibitors as new leads to target parasitic diarrheal diseases.
abstract: Entamoeba histolytica and Giardia lamblia are anaerobic protozoan parasites that cause amebiasis and giardiasis, two of the most common diarrheal diseases worldwide. Current therapy relies on metronidazole, but resistance has been reported and the drug has significant adverse effects. Therefore, it is critical to search for effective, better-tolerated antiamebic and antigiardial drugs. We synthesized several examples of a recently reported class of Hsp90 inhibitors and evaluated these compounds as potential leads for antiparasitic chemotherapy. Several of these inhibitors showed strong in vitro activity against both E. histolytica and G. lamblia trophozoites. The inhibitors were rescreened to discriminate between amebicidal and giardicidal activity and general cytotoxicity toward a mammalian cell line. No mammalian cytotoxicity was found at >100 μM for 48 h for any of the inhibitors. To understand the mechanism of action, a competitive binding assay was performed using the fluorescent ATP analogue bis-ANS (4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid dipotassium salt) and recombinant E. histolytica Hsp90 preincubated in both the presence and absence of Hsp90 inhibitors. There was significant reduction in fluorescence compared to the level in the control, suggesting that E. histolytica Hsp90 is a selective target. The in vivo efficacy and safety of one Hsp90 inhibitor in a mouse model of amebic colitis and giardiasis was demonstrated by significant inhibition of parasite growth at a single oral dose of 5 mg/kg of body weight/day for 7 days and 10 mg/kg/day for 3 days. Considering the results for in vitro activity and in vivo efficacy, Hsp90 inhibitors represent a promising therapeutic option for amebiasis and giardiasis.
authors.affiliation: Center for Discovery and Innovation in Parasitic Diseases, University of California, San Francisco, San Francisco, California, USA anjan.debnath@ucsf.edu.
authors.forename: Anjan
authors.initials: A
authors.lastname: Debnath
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Calgary, Alberta, Canada.
authors.forename: Dea
authors.initials: D
authors.lastname: Shahinas
authors.affiliation: Small Molecule Discovery Center, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Clifford
authors.initials: C
authors.lastname: Bryant
authors.affiliation: Department of Pathology, University of California, San Diego, San Diego, California, USA.
authors.forename: Ken
authors.initials: K
authors.lastname: Hirata
authors.affiliation: Department of Medicine, University of California, San Diego, San Diego, California, USA.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Miyamoto
authors.affiliation: Department of Pathology, University of California, San Diego, San Diego, California, USA.
authors.forename: Grace
authors.initials: G
authors.lastname: Hwang
authors.affiliation: Center for Discovery and Innovation in Parasitic Diseases, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Jiri
authors.initials: J
authors.lastname: Gut
authors.affiliation: Small Molecule Discovery Center, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Renslo
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Calgary, Alberta, Canada.
authors.forename: Dylan R
authors.initials: DR
authors.lastname: Pillai
authors.affiliation: Department of Medicine, University of California, San Diego, San Diego, California, USA.
authors.forename: Lars
authors.initials: L
authors.lastname: Eckmann
authors.affiliation: Department of Pathology, University of California, San Diego, San Diego, California, USA.
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Reed
authors.affiliation: Center for Discovery and Innovation in Parasitic Diseases, University of California, San Francisco, San Francisco, California, USA.
authors.forename: James H
authors.initials: JH
authors.lastname: McKerrow
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D000818:Animals; D000981:Antiprotozoal Agents / Q000627:therapeutic use; D001549:Benzamides / Q000627:therapeutic use; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D004748:Entamoeba histolytica / Q000187:drug effects*; D004749:Entamoebiasis / Q000188:drug therapy* / Q000469:parasitology; D016829:Giardia lamblia / Q000187:drug effects*; D005873:Giardiasis / Q000188:drug therapy* / Q000469:parasitology; D005998:Glycine; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D007191:Indazoles / Q000627:therapeutic use; D019169:Jurkat Cells; D051379:Mice; D021261:Parasitic Sensitivity Tests; D053058:Trophozoites / Q000187:drug effects
chemical_list: D000817:Anilino Naphthalenesulfonates; D000981:Antiprotozoal Agents; D001549:Benzamides; D018841:HSP90 Heat-Shock Proteins; D007191:Indazoles; C035763:5,5'-bis(8-(phenylamino)-1-naphthalenesulfonate); C561943:SNX-5422; D005998:Glycine