title: Oxidative stress levels are correlated with P15 and P16 gene promoter methylation in myelodysplastic syndrome patients.
abstract: Oxidative stress and abnormal DNA methylation have been implicated in some types of cancer, namely in myelodysplastic syndromes (MDS). Since both mechanisms are observed in MDS patients, we analyzed the correlation of intracellular levels of peroxides, superoxide anion, and glutathione (GSH), as well as ratios of peroxides/GSH and superoxide/GSH, with the methylation status of P15 and P16 gene promoters in bone marrow leukocytes from MDS patients. Compared to controls, these patients had lower GSH content, higher peroxide levels, peroxides/GSH and superoxide/GSH ratios, as well as higher methylation frequency of P15 and P16 gene promoters. Moreover, patients with methylated P15 gene had higher oxidative stress levels than patients without methylation (peroxides: 460 ± 42 MIF vs 229 ± 25 MIF, p = 0.001; superoxide: 383 ± 48 MIF vs 243 ± 17 MIF, p = 0.022; peroxides/GSH: 2.50 ± 0.08 vs 1.04 ± 0.34, p < 0.001; superoxide/GSH: 1.76 ± 0.21 vs 1.31 ± 0.10, p = 0.007). Patients with methylated P16 and at least one methylated gene had higher peroxide levels as well as peroxides/GSH ratio than patients without methylation. Interestingly, oxidative stress levels allow the discrimination of patients without methylation from ones with methylated P15, methylated P16, or at least one methylated (P15 or P16) promoter. Taken together, these findings support the hypothesis that oxidative stress is correlated with P15 and P16 hypermethylation.
authors.affiliation: Applied Molecular Biology, University Clinic of Hematology, Center of Investigation in Environment, Genetics and Oncobiology (CIMAGO), Faculty of Medicine, University of Coimbra (FMUC), Azinhaga de Santa Comba - Celas, 3000-548, Coimbra, Portugal.|Center for Neuroscience and Cell Biology (CNC), Coimbra, Portugal.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Gonçalves
authors.affiliation: Applied Molecular Biology, University Clinic of Hematology, Center of Investigation in Environment, Genetics and Oncobiology (CIMAGO), Faculty of Medicine, University of Coimbra (FMUC), Azinhaga de Santa Comba - Celas, 3000-548, Coimbra, Portugal.|Clinical Hematology Department, Centro Hospitalar e Universitário de Coimbra (CHUC), Coimbra, Portugal.
authors.forename: Emília
authors.initials: E
authors.lastname: Cortesão
authors.affiliation: Laboratory for Biostatistics and Medical Informatics, Faculty of Medicine, University of Coimbra (FMUC), Coimbra, Portugal.
authors.forename: Barbara
authors.initials: B
authors.lastname: Oliveiros
authors.affiliation: Immunology, Faculty of Medicine, University of Coimbra (FMUC), Coimbra, Portugal.
authors.forename: Vera
authors.initials: V
authors.lastname: Alves
authors.affiliation: Clinical Hematology Department, Centro Hospitalar e Universitário de Coimbra (CHUC), Coimbra, Portugal.
authors.forename: Ana Isabel
authors.initials: AI
authors.lastname: Espadana
authors.affiliation: Applied Molecular Biology, University Clinic of Hematology, Center of Investigation in Environment, Genetics and Oncobiology (CIMAGO), Faculty of Medicine, University of Coimbra (FMUC), Azinhaga de Santa Comba - Celas, 3000-548, Coimbra, Portugal.|Clinical Hematology Department, Centro Hospitalar e Universitário de Coimbra (CHUC), Coimbra, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Rito
authors.affiliation: Clinical Hematology Department, Centro Hospitalar e Universitário de Coimbra (CHUC), Coimbra, Portugal.
authors.forename: Emília
authors.initials: E
authors.lastname: Magalhães
authors.affiliation: Medicine Department, Hospital Distrital da Figueira da Foz, Figueira da Foz, Portugal.
authors.forename: Sónia
authors.initials: S
authors.lastname: Pereira
authors.affiliation: Medicine Department, Hospital Distrital da Figueira da Foz, Figueira da Foz, Portugal.
authors.forename: Amélia
authors.initials: A
authors.lastname: Pereira
authors.affiliation: Oncology Department, Centro Hospital e Universitário de Coimbra (CHUC), Coimbra, Portugal.|University Clinic of Oncology, Faculty of Medicine, University of Coimbra (FMUC), Coimbra, Portugal.
authors.forename: José Manuel Nascimento
authors.initials: JM
authors.lastname: Costa
authors.affiliation: Molecular Genetics and Pathology Unit, Hospital of Divino Espírito Santo of Ponta Delgada EPE, São Miguel Island, Azores, Portugal.|Azores Genetics Research Group, Instituto Gulbenkian de Ciência, Oeiras, Portugal.|Faculty of Sciences, Biosystems & Integrative Sciences Institute (BioISI), University of Lisboa, Lisbon, Portugal.
authors.forename: Luisa
authors.initials: L
authors.lastname: Mota-Vieira
authors.affiliation: Applied Molecular Biology, University Clinic of Hematology, Center of Investigation in Environment, Genetics and Oncobiology (CIMAGO), Faculty of Medicine, University of Coimbra (FMUC), Azinhaga de Santa Comba - Celas, 3000-548, Coimbra, Portugal. absarmento@fmed.uc.pt.|Center for Neuroscience and Cell Biology (CNC), Coimbra, Portugal. absarmento@fmed.uc.pt.|Clinical Hematology Department, Centro Hospitalar e Universitário de Coimbra (CHUC), Coimbra, Portugal. absarmento@fmed.uc.pt.
authors.forename: Ana Bela
authors.identifier: http://orcid.org/0000-0002-4142-4841
authors.initials: AB
authors.lastname: Sarmento-Ribeiro
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050762:Cyclin-Dependent Kinase Inhibitor p15 / Q000235:genetics*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D019175:DNA Methylation; D005260:Female; D005978:Glutathione / Q000032:analysis; D006801:Humans; D007962:Leukocytes / Q000737:chemistry / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000473:pathology*; D018384:Oxidative Stress; D010545:Peroxides / Q000032:analysis; D011401:Promoter Regions, Genetic
chemical_list: C493966:CDKN2B protein, human; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D010545:Peroxides; D005978:Glutathione
keywords: DNA methylation; Myelodysplasia; Oxidative stress; Tumor suppressor genes