title: Redox regulation of metabolic and signaling pathways by thioredoxin and glutaredoxin in NOS-3 overexpressing hepatoblastoma cells.
abstract: Nitric oxide (NO) plays relevant roles in signal transduction in physiopathology and its effects are dependent on several environmental factors. NO has both pro-apoptotic and anti-apoptotic functions but the molecular mechanisms responsible for these opposite effects are not fully understood. The action of NO occurs mainly through redox changes in target proteins, particularly by S-nitrosylation of reactive cysteine residues. Thioredoxin (Trx) and glutaredoxin (Grx) systems are the main cellular controllers of the thiolic redox state of proteins exerting controversial effects on apoptosis with consequences for the resistance to or the development of cancer. The aim of this study was to ascertain whether Trx and/or Grx systems mediate the antiproliferative effect of NO on hepatoblastoma cells by modulating the redox-state of key proteins. Proliferation decreased and apoptosis increased in HepG2 cells overexpressing Nitric Oxide Synthase-3 (NOS-3) as a result of multilevel cellular responses to the oxidative environment generated by NO. Enzyme levels and cysteine redox state at several metabolic checkpoints were consistent with prominence of the pentose phosphate pathway to direct the metabolic flux toward NADPH for antioxidant defense and lowering of nucleotide biosynthesis and hence proliferation. Proteins involved in cell survival pathways, proteins of the redoxin systems and phosphorylation of MAPK were all significantly increased accompanied by a shift of the thiolic redox state of Akt1, Trx1 and Grx1 to more oxidized. Silencing of Trx1 and Grx1 neutralized the increases in CD95, Akt1 and pAkt levels induced by NO and produced a marked increase in caspase-3 and -8 activities in both control and NOS-3 overexpressing cells concomitant with a decrease in the number of cells. These results demonstrate that the antiproliferative effect of NO is actually hampered by Trx1 and Grx1 and support the strategy of weakening the thiolic antioxidant defenses when designing new antitumoral therapies.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain; Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain. Electronic address: raulangello@hotmail.com.
authors.forename: Raúl
authors.initials: R
authors.lastname: González
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain.
authors.forename: M José
authors.initials: MJ
authors.lastname: López-Grueso
authors.affiliation: Departamento de Cirugía General, Hospital Universitario Virgen del Rocío/Instituto de Biomedicina de Sevilla (IBiS)/CSIC/Universidad de Sevilla, Sevilla, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Muntané
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain; Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.
authors.forename: J Antonio
authors.initials: JA
authors.lastname: Bárcena
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain; Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.
authors.forename: C Alicia
authors.initials: CA
authors.lastname: Padilla
mesh_terms: D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003545:Cysteine / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D054477:Glutaredoxins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D009249:NADP / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology*; D052250:Nitric Oxide Synthase Type III / Q000235:genetics* / Q000378:metabolism; D010084:Oxidation-Reduction; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013879:Thioredoxins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D019014:fas Receptor / Q000235:genetics / Q000378:metabolism
chemical_list: C491901:FAS protein, human; C516005:GLRX protein, human; D054477:Glutaredoxins; D034741:RNA, Small Interfering; C491203:TXN protein, human; D019014:fas Receptor; D009569:Nitric Oxide; D013879:Thioredoxins; D009249:NADP; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8; D003545:Cysteine
keywords: Apoptosis; Cancer; Glutaredoxin; Oxidative/nitrosative stress; Thioredoxin