Unknown,Transcriptomics,Genomics,Proteomics

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Expression data from paediatric ependymoma short-term cell cultures

ABSTRACT: Promoter hypermethylation and transcriptional silencing is a common epigenetic mechanism of tumour suppressor inactivation in cancer, including malignant brain tumours. To identify targets of epigenetic silencing mediated by CpG island methylation in paediatric ependymoma, we used a pharmacological unmasking approach through treatment with the demethylating agent 5-Aza-2M-bM-^@M-^Y-deoxycytidine followed by global expression microarray analysis. Three short-term ependymoma cell cultures were used for whole genome expression analysis following treatment with the demethylating agent 5-Aza-dC (5 M-BM-5mol/L) or mock-treated with DMSO (M-bM-^IM-$0.1% v/v) for 96-hrs.

ORGANISM(S): Homo sapiens

SUBMITTER: Katherine Karakoula

PROVIDER: E-GEOD-45437 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Epigenetic changes largely contribute to the regulation of gene expression in cancer cells. DNA methylation is part of the epigenetic gene regulation complex which is relevant for the pathogenesis of cancer. We performed a genome-wide search for methylated CpG islands in tumors and corresponding non-malignant lung tissue samples of 101 stage I-III non-small cell lung cancer (NSCLC) patients by combining methylated DNA immunoprecipitation and microarray analysis using NimbleGenM-BM-4s 385K Human CpG Island plus Promoter arrays. By testing for differences in methylation between tumors and corresponding non-malignant lung tissues, we identified 298 tumor-specifically methylated genes. From many of these genes epigenetic regulation was unknown so far. Gene Ontology analysis revealed an over-representation of genes involved in regulation of gene expression and cell adhesion. Expression of 182 of 298 genes was found to be upregulated after 5-aza-2M-BM-4-deoxycytidine (Aza-dC) and/or trichostatin A (TSA) treatment of 3 NSCLC cell lines by Affymetrix microarray analysis. In addition, methylation of selected genes in primary NSCLCs and corresponding non-malignant lung tissue samples were analyzed by methylation-sensitive high resolution melting analysis (MS-HRM). Our results obtained by MS-HRM analysis confirmed our data obtained by MeDIP-chip analysis. Moreover, by comparing methylation results from MeDIP-chip analysis with clinico-pathological parameters of the patients we observed methylation of HOXA2 as potential parameter for shorter disease-free survival of NSCLC patients. In conclusion, using a genome-wide approach we identified a large number of tumor-specifically methylated genes in NSCLC patients. Our results stress the importance of DNA methylation for the pathogenesis of NSCLCs. Overall, samples of 3 untreated, with Aza-dC treated and with Aza-dC/TSA treated NSCLC cell lines were hybridized to Affymetrix HG-U133_plus_2.0 microarrays (18 in total).

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Expression data from paediatric ependymoma short-term cell cultures

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