title: 21-Benzylidene digoxin: a proapoptotic cardenolide of cancer cells that up-regulates Na,K-ATPase and epithelial tight junctions.
abstract: Cardiotonic steroids are used to treat heart failure and arrhythmia and have promising anticancer effects. The prototypic cardiotonic steroid ouabain may also be a hormone that modulates epithelial cell adhesion. Cardiotonic steroids consist of a steroid nucleus and a lactone ring, and their biological effects depend on the binding to their receptor, Na,K-ATPase, through which, they inhibit Na+ and K+ ion transport and activate of several intracellular signaling pathways. In this study, we added a styrene group to the lactone ring of the cardiotonic steroid digoxin, to obtain 21-benzylidene digoxin (21-BD), and investigated the effects of this synthetic cardiotonic steroid in different cell models. Molecular modeling indicates that 21-BD binds to its target Na,K-ATPase with low affinity, adopting a different pharmacophoric conformation when bound to its receptor than digoxin. Accordingly, 21-DB, at relatively high µM amounts inhibits the activity of Na,K-ATPase α1, but not α2 and α3 isoforms. In addition, 21-BD targets other proteins outside the Na,K-ATPase, inhibiting the multidrug exporter Pdr5p. When used on whole cells at low µM concentrations, 21-BD produces several effects, including: 1) up-regulation of Na,K-ATPase expression and activity in HeLa and RKO cancer cells, which is not found for digoxin, 2) cell specific changes in cell viability, reducing it in HeLa and RKO cancer cells, but increasing it in normal epithelial MDCK cells, which is different from the response to digoxin, and 3) changes in cell-cell interaction, altering the molecular composition of tight junctions and elevating transepithelial electrical resistance of MDCK monolayers, an effect previously found for ouabain. These results indicate that modification of the lactone ring of digoxin provides new properties to the compound, and shows that the structural change introduced could be used for the design of cardiotonic steroid with novel functions.
authors.affiliation: Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Sayonarah C
authors.initials: SC
authors.lastname: Rocha
authors.affiliation: Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Marco T C
authors.initials: MT
authors.lastname: Pessoa
authors.affiliation: Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Luiza D R
authors.initials: LD
authors.lastname: Neves
authors.affiliation: Laboratório de Síntese Orgânica, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Silmara L G
authors.initials: SL
authors.lastname: Alves
authors.affiliation: Laboratório de Biologia Celular e Inovação Biotecnológica, Fundação Ezequiel Dias, Belo Horizonte, MG, Brazil.
authors.forename: Luciana M
authors.initials: LM
authors.lastname: Silva
authors.affiliation: Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Herica L
authors.initials: HL
authors.lastname: Santos
authors.affiliation: Laboratório de Bioinformática, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Soraya M F
authors.initials: SM
authors.lastname: Oliveira
authors.affiliation: Laboratório de Bioinformática, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Alex G
authors.initials: AG
authors.lastname: Taranto
authors.affiliation: Laboratório de Bioinformática, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Moacyr
authors.initials: M
authors.lastname: Comar
authors.affiliation: Laboratório de Biologia Celular e Mutagenicidade, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Isabella V
authors.initials: IV
authors.lastname: Gomes
authors.affiliation: Laboratório de Biologia Celular e Mutagenicidade, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Fabio V
authors.initials: FV
authors.lastname: Santos
authors.affiliation: Laboratório de Farmacologia Bioquímica e Molecular, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Natasha
authors.initials: N
authors.lastname: Paixão
authors.affiliation: Laboratório de Farmacologia Bioquímica e Molecular, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Luis E M
authors.initials: LE
authors.lastname: Quintas
authors.affiliation: Laboratório de Farmacologia Bioquímica e Molecular, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: François
authors.initials: F
authors.lastname: Noël
authors.affiliation: Laboratório de Bioquímica Microbiana, Instituto de Microbiologia Paulo Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Antonio F
authors.initials: AF
authors.lastname: Pereira
authors.affiliation: Laboratório de Bioquímica Microbiana, Instituto de Microbiologia Paulo Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil; Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro (IFRJ), Rio de Janeiro, RJ, Brazil.
authors.forename: Ana C S C
authors.initials: AC
authors.lastname: Tessis
authors.affiliation: Laboratório de Biologia Molecular e Doenças Endêmicas, Instituto Oswaldo Cruz/Fiocruz, Rio de Janeiro, RJ, Brazil.
authors.forename: Natalia L S
authors.initials: NL
authors.lastname: Gomes
authors.affiliation: Laboratório de Biologia Molecular e Doenças Endêmicas, Instituto Oswaldo Cruz/Fiocruz, Rio de Janeiro, RJ, Brazil.
authors.forename: Otacilio C
authors.initials: OC
authors.lastname: Moreira
authors.affiliation: Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico.
authors.forename: Ruth
authors.initials: R
authors.lastname: Rincon-Heredia
authors.affiliation: Laboratório de Bioquímica de Parasitos, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Varotti
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas, United States of America.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Blanco
authors.affiliation: Laboratório de Síntese Orgânica, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Jose A F P
authors.initials: JA
authors.lastname: Villar
authors.affiliation: Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico.
authors.forename: Rubén G
authors.initials: RG
authors.lastname: Contreras
authors.affiliation: Laboratório de Bioquímica Celular, Universidade Federal de São João del Rei, Campus Centro-Oeste Dona Lindú, Divinópolis, MG, Brazil.
authors.forename: Leandro A
authors.initials: LA
authors.lastname: Barbosa
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002298:Cardenolides / Q000378:metabolism / Q000494:pharmacology; D045744:Cell Line, Tumor; D004077:Digoxin / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008968:Molecular Conformation; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019108:Tight Junctions / Q000187:drug effects*
chemical_list: D002298:Cardenolides; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase