title: Giardial triosephosphate isomerase as possible target of the cytotoxic effect of omeprazole in Giardia lamblia.
abstract: Giardiasis is highly prevalent in the developing world, and treatment failures with the standard drugs are common. This work deals with the proposal of omeprazole as a novel antigiardial drug, focusing on a giardial glycolytic enzyme used to follow the cytotoxic effect at the molecular level. We used recombinant technology and enzyme inactivation to demonstrate the capacity of omeprazole to inactivate giardial triosephosphate isomerase, with no adverse effects on its human counterpart. To establish the specific target in the enzyme, we used single mutants of every cysteine residue in triosephosphate isomerase. The effect on cellular triosephosphate isomerase was evaluated by following the remnant enzyme activity on trophozoites treated with omeprazole. The interaction of omeprazole with giardial proteins was analyzed by fluorescence spectroscopy. The susceptibility to omeprazole of drug-susceptible and drug-resistant strains of Giardia lamblia was evaluated to demonstrate its potential as a novel antigiardial drug. Our results demonstrate that omeprazole inhibits giardial triosephosphate isomerase in a species-specific manner through interaction with cysteine at position 222. Omeprazole enters the cytoplasmic compartment of the trophozoites and inhibits cellular triosephosphate isomerase activity in a dose-dependent manner. Such inhibition takes place concomitantly with the cytotoxic effect caused by omeprazole on trophozoites. G. lamblia triosephosphate isomerase (GlTIM) is a cytoplasmic protein which can help analyses of how omeprazole works against the proteins of this parasite and in the effort to understand its mechanism of cytotoxicity. Our results demonstrate the mechanism of giardial triosephosphate isomerase inhibition by omeprazole and show that this drug is effective in vitro against drug-resistant and drug-susceptible strains of G. lamblia.
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Horacio
authors.initials: H
authors.lastname: Reyes-Vivas
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Ignacio
authors.initials: I
authors.lastname: de la Mora-de la Mora
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Adriana
authors.initials: A
authors.lastname: Castillo-Villanueva
authors.affiliation: Centro Médico Nacional Siglo XXI, IMSS, Mexico City, Mexico.
authors.forename: Lilian
authors.initials: L
authors.lastname: Yépez-Mulia
authors.affiliation: Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Gloria
authors.initials: G
authors.lastname: Hernández-Alcántara
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Rosalia
authors.initials: R
authors.lastname: Figueroa-Salazar
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Itzhel
authors.initials: I
authors.lastname: García-Torres
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Saúl
authors.initials: S
authors.lastname: Gómez-Manzo
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Sara T
authors.initials: ST
authors.lastname: Méndez
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: América
authors.initials: A
authors.lastname: Vanoye-Carlo
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Jaime
authors.initials: J
authors.lastname: Marcial-Quino
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Angélica
authors.initials: A
authors.lastname: Torres-Arroyo
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Jesús
authors.initials: J
authors.lastname: Oria-Hernández
authors.affiliation: Hospital General Dr. Manuel Gea González, Mexico City, Mexico.
authors.forename: Pedro
authors.initials: P
authors.lastname: Gutiérrez-Castrellón
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico.
authors.forename: Sergio
authors.initials: S
authors.lastname: Enríquez-Flores
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, Mexico City, Mexico glv_1999@yahoo.com.
authors.forename: Gabriel
authors.initials: G
authors.lastname: López-Velázquez
mesh_terms: D015766:Albendazole / Q000494:pharmacology; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D061245:Axenic Culture; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D016829:Giardia lamblia / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development / Q000302:isolation & purification; D006801:Humans; D008795:Metronidazole / Q000494:pharmacology; D009154:Mutation; D009574:Nitro Compounds; D009853:Omeprazole / Q000494:pharmacology*; D021261:Parasitic Sensitivity Tests; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013844:Thiazoles / Q000494:pharmacology; D014305:Triose-Phosphate Isomerase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D053058:Trophozoites / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development
chemical_list: D000981:Antiprotozoal Agents; D004791:Enzyme Inhibitors; D009574:Nitro Compounds; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D013844:Thiazoles; D008795:Metronidazole; D014305:Triose-Phosphate Isomerase; D015766:Albendazole; D003545:Cysteine; D009853:Omeprazole; C041747:nitazoxanide