title: MYCN is recruited to the RASSF1A promoter but is not critical for DNA hypermethylation in neuroblastoma.
abstract: Tumor suppressor genes such as RASSF1A are often epigenetically repressed by DNA hypermethylation in neuroblastoma, where the MYCN proto-oncogene is frequently amplified. MYC has been shown to associate with DNA methyltransferases, thereby inducing transcriptional repression of target genes, which suggested that MYCN might play a similar mechanistic role in the hypermethylation of tumor suppressor genes in neuroblastoma. This study tested that hypothesis by using co-immunoprecipitation and ChIP to investigate MYCN-DNA methyltransferase interactions, together with MYCN knock-down and over-expression systems to examine the effect of MYCN expression changes on gene methylation, employing both candidate gene and genome-wide assays. We show that MYCN interacts with DNA methyltransferases and is recruited to the promoter region of RASSF1A. However, using four model systems, we showed that long-term silencing of MYCN induces only a small loss of DNA methylation at the RASSF1A promoter in MYCN amplified neuroblastoma cell lines and over-expression of MYCN does not induce any DNA methylation, suggesting that MYCN is not critical for DNA hypermethylation in neuroblastoma.
authors.affiliation: School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK.
authors.forename: Jessica
authors.initials: J
authors.lastname: Charlet
authors.forename: Marianna
authors.initials: M
authors.lastname: Szemes
authors.forename: Karim T A
authors.initials: KT
authors.lastname: Malik
authors.forename: Keith W
authors.initials: KW
authors.lastname: Brown
mesh_terms: D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D004273:DNA, Neoplasm / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D047468:Immunoprecipitation; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000235:genetics* / Q000473:pathology; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D015513:Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics*; D000090063:Proto-Oncogene Mas; D034741:RNA, Small Interfering / Q000235:genetics; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: D004273:DNA, Neoplasm; C000717967:DNMT3A protein, human; C000715470:MAS1 protein, human; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D000090063:Proto-Oncogene Mas; C411762:RASSF1 protein, human; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A
keywords: DNA hypermethylation; MYCN; epigenetics; neuroblastoma