title: The stepwise selection for ketoconazole resistance induces upregulation of C14-demethylase (CYP51) in Leishmania amazonensis.
abstract: Ketoconazole is a clinically safe antifungal agent that also inhibits the growth of Leishmania spp. A study was undertaken to determine whether Leishmania parasites are prone to becoming resistant to ketoconazole by upregulating C14-demethylase after stepwise pharmacological pressure. Leishmania amazonensis promastigotes [inhibitory concentration (IC)₅₀ = 2 µM] were subjected to stepwise selection with ketoconazole and two resistant lines were obtained, La8 (IC₅₀ = 8 µM) and La10 (IC₅₀ = 10 µM). As a result, we found that the resistance level was directly proportional to the C14-demethylase mRNA expression level; we also observed that expression levels were six and 12 times higher in La8 and La10, respectively. This is the first demonstration that L. amazonensis can up-regulate C14-demethylase in response to drug pressure and this report contributes to the understanding of the mechanisms of parasite resistance.
authors.affiliation: Laboratório de Bioquímica de Tripanosomatídeos, Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro, RJ, Brasil.
authors.forename: Valter Viana
authors.initials: VV
authors.lastname: Andrade-Neto
authors.forename: Herbert Leonel de
authors.initials: HL
authors.lastname: Matos-Guedes
authors.forename: Daniel Cláudio de Oliveira
authors.initials: DC
authors.lastname: Gomes
authors.forename: Marilene Marcuzzo do
authors.initials: MM
authors.lastname: Canto-Cavalheiro
authors.forename: Bartira
authors.initials: B
authors.lastname: Rossi-Bergmann
authors.forename: Eduardo Caio
authors.initials: EC
authors.lastname: Torres-Santos
mesh_terms: D000981:Antiprotozoal Agents / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D007654:Ketoconazole / Q000494:pharmacology*; D007894:Leishmania mexicana / Q000187:drug effects* / Q000201:enzymology*; D021261:Parasitic Sensitivity Tests; D012333:RNA, Messenger / Q000032:analysis; D016053:RNA, Protozoan / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D058886:Sterol 14-Demethylase / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D000981:Antiprotozoal Agents; D012333:RNA, Messenger; D016053:RNA, Protozoan; D058886:Sterol 14-Demethylase; D007654:Ketoconazole