title: Single CpG island methylation is not sufficient to maintain the silenced expression of CASPASE-8 apoptosis-related gene among women with epithelial ovarian cancer.
abstract: Despite impressive research efforts, the biology of epithelial ovarian cancer (EOC) remains poorly understood and alterations in the expression of CASPASE-8 contribute to a worse tumor prognosis. This study assesses the methylation of the CpG island within the CASPASE-8 promoter and CASPASE-8 gene expression both in cystadenoma tumors and in primary and metastatic EOC. DNA and RNA were obtained from women with normal ovarian tissues (n=18), ovarian serous cystadenoma tumors (n=11) and EOC (n=16) using Trizol(®). The methylation frequency of the CpG island in the CASPASE-8 promoter was assessed using the methylation-specific PCR assay after DNA bisulfite conversion. Quantitative PCR was performed to quantify the relative levels of CASPASE-8 in each sample. The differences between samples with each group were evaluated using the Mann-Whitney U and Kruskal-Wallis tests as indicated. Hemimethylation of the CASPASE-8 promoter was found in 11.8% of the normal ovary samples, 20% of the cystadenoma tumors and 20% of the metastatic EOC, while methylation of the CASPASE-8 promoter was absent in the EOC primary tissues (P=0.047). An increased CASPASE-8 expression level was observed in all tumor groups. Significant differences were observed in the CASPASE-8 expression levels when compared with all ovarian tumor groups (P=0.0278). Promoter DNA methylation did not associate with expression levels of CASPASE-8, suggesting the presence of other mechanisms in relation to gene expression control in EOC; thus providing a better understanding of this complex disease.
authors.affiliation: Serviço de Biologia Celular, Diretoria de Pesquisa e Desenvolvimento da Fundação Ezequiel Dias, Belo Horizonte, M.G., Brazil; Departamento de Ginecologia e Obstetrícia da Faculdade de Medicina da Universidade Estadual de São Paulo "Júlio de Mesquita Filho", Botucatu, S.P., Brazil.
authors.forename: Letícia da Conceição
authors.initials: Lda C
authors.lastname: Braga
authors.affiliation: Serviço de Biologia Celular, Diretoria de Pesquisa e Desenvolvimento da Fundação Ezequiel Dias, Belo Horizonte, M.G., Brazil.
authors.forename: Luciana Maria
authors.initials: LM
authors.lastname: Silva
authors.affiliation: Serviço de Biologia Celular, Diretoria de Pesquisa e Desenvolvimento da Fundação Ezequiel Dias, Belo Horizonte, M.G., Brazil.
authors.forename: Ana Paula Álvares da Silva
authors.initials: AP
authors.lastname: Ramos
authors.affiliation: Serviço de Biologia Celular, Diretoria de Pesquisa e Desenvolvimento da Fundação Ezequiel Dias, Belo Horizonte, M.G., Brazil.
authors.forename: Josiane Barbosa
authors.initials: JB
authors.lastname: Piedade
authors.affiliation: Departamento de Patologia e Medicina Legal da Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, M.G., Brazil.
authors.forename: Paula Vieira Teixeira
authors.initials: PV
authors.lastname: Vidigal
authors.affiliation: Departamento de Ginecologia e Obstetrícia da Faculdade de Medicina da Universidade Estadual de São Paulo "Júlio de Mesquita Filho", Botucatu, S.P., Brazil.
authors.forename: Paulo
authors.initials: P
authors.lastname: Traiman
authors.affiliation: Departamento de Ginecologia e Obstetrícia da Faculdade de Medicina da Universidade Federal de Minas Gerais, Avenida Professor Alfredo Balena, 190, Santa Efigênia, Belo Horizonte, M.G., Brazil; Departamento de Ginecologia e Obstetrícia da Faculdade de Medicina da Universidade Estadual de São Paulo "Júlio de Mesquita Filho", Botucatu, S.P., Brazil. Electronic address: agnaldo.ufmg@gmail.com.
authors.forename: Agnaldo Lopes
authors.initials: AL
authors.lastname: da Silva Filho
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000235:genetics; D000077216:Carcinoma, Ovarian Epithelial; D016022:Case-Control Studies; D053181:Caspase 8 / Q000235:genetics*; D018899:CpG Islands / Q000235:genetics*; D018293:Cystadenoma, Serous / Q000235:genetics*; D019175:DNA Methylation / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009375:Neoplasms, Glandular and Epithelial / Q000235:genetics*; D010051:Ovarian Neoplasms / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D011446:Prospective Studies; D018709:Statistics, Nonparametric
chemical_list: D053181:Caspase 8
keywords: CASPASE-8; Epithelial ovarian cancer; Expression