Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Genome-scale analysis of aberrant DNA methylation in colorectal cancer

ABSTRACT: To characterize DNA methylation-based subgroups in colorectal cancer, we performed genome-scale DNA methylation profiling of 125 colorectal tumor samples and 29 histologically normal-adjacent colonic tissue samples using the Illumina Infinium DNA methylation assay, which assesses the DNA methylation status of 27,578 CpG sites located at the promoter regions of 14,495 protein-coding genes. We identified four DNA methylation-based subgroups of CRC using model-based cluster analyses. Each subtype shows characteristic genetic and clinical features, indicating that they represent biologically distinct subgroups. Bisulfite converted DNA from fresh frozen 125 colorectal tumors and 29 adjacent normal tissues were hybridized to the Illumina Infinium 27k Human Methylation Beadchip v1.2

ORGANISM(S): Homo sapiens

SUBMITTER: Toshinori Hinoue

PROVIDER: E-GEOD-25062 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Genome-scale analysis of aberrant DNA methylation in colorectal cancer.

Hinoue Toshinori T Weisenberger Daniel J DJ Lange Christopher P E CP Shen Hui H Byun Hyang-Min HM Van Den Berg David D Malik Simeen S Pan Fei F Noushmehr Houtan H van Dijk Cornelis M CM Tollenaar Rob A E M RA Laird Peter W PW

Genome research 20110609 2

Colorectal cancer (CRC) is a heterogeneous disease in which unique subtypes are characterized by distinct genetic and epigenetic alterations. Here we performed comprehensive genome-scale DNA methylation profiling of 125 colorectal tumors and 29 adjacent normal tissues. We identified four DNA methylation-based subgroups of CRC using model-based cluster analyses. Each subtype shows characteristic genetic and clinical features, indicating that they represent biologically distinct subgroups. A CIMP- ...[more]

PMID: 21659424

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Project description:Serrated adenocarcinoma (SAC) is a recently recognized colorectal cancer (CRC) subtype accounting for 7.5 - 8.7% of CRCs. It has been shown that SAC has a worse prognosis and has different molecular and immunohistochemical features compared to conventional carcinoma (CC) but, to date, there is no study analysing its methylome profile. We have investigated the methylation status of 450,000 CpG sites using the Infinium Human Methylation 450 BeadChip array in 103 colorectal specimens from Spanish and Finnish patients. The comparison between the epigenetic signature of 36 SACs and 34 matched CCs was established with the aim of identifying the functions which characterize SAC biology and also the most differentially methylated genes for subsequent validatation by pyrosequencing, methylation-specific PCR, qPCR and immunohistochemistry, including additional cases. Microarray data showed a higher representation of morphogenesis-, neurogenesis-, cytoskeleton- and vesicle-transport-related functions and also significant differential methylation of 15 genes, including the iodothyronine deiodinase DIO3 and the forkhead family transcription factor FOXD2 genes which were validated at the CpG, mRNA and protein level. A quantification study of the methylation status of CpG sequences in FOXD2 demonstrated a novel region controlling gene expression. Moreover, differences in these markers were also evident when comparing SAC with CRC showing molecular and histological features of high level microsatellite instability. This methylome study demonstrates that SAC has a distinct epigenetic regulation pattern resulting in different biological functions and that DIO3 and FOXD2 might be molecular targets for a specific histology-oriented treatment of CRC. HumanMethylation450K BeadChip (Illumina, Inc, San Diego, CA), using Infinium HD Methylation assay for genome-wide DNA methylation screening, was employed. In brief, genomic DNA (1000 ng) from each sample was bisulfite converted with the EZ DNA Methylation Kit (Zymo Research, Orange, CA) according to the manufacturer´s recommendations. Bisulfite-treated DNA was isothermally amplified at 37°C (20-24h) and the DNA product was fragmented by an endpoint enzymatic process, then precipitated, resuspended, applied to an Infinium Human Methylation450K BeadChip (Illumina, San Diego, CA, USA) and hybridized at 48°C (16-24h). The fluorescently-stained chip was imaged by the Illumina i-SCAN and Illumina's Genome Studio program (Methylation Module) was used to analyze BeadArray data to assign site-specific DNA methylation β-values to each CpG site.

Project description:Lung cancer is the leading cause of cancer death worldwide and adenocarcinoma is its most common histological subtype. Clinical and molecular evidence indicates that lung adenocarcinoma is a heterogeneous disease, which has important implications for treatment. Here we performed genome-scale DNA methylation profiling using the Illumina Infinium HumanMethylation27 platform on 59 matched lung adenocarcinoma/non-tumor lung samples, with genome-scale verification on an independent set of tissues. We identified 766 genes showing altered DNA methylation between tumors and non-tumor lung. By integrating DNA methylation and mRNA expression data, we identified 164 hypermethylated genes showing concurrent downregulation, and 57 hypomethylated genes showing increased expression. Integrated pathways analysis indicates that these genes are involved in cell differentiation, epithelial to mesenchymal transition, RAS and WNT signaling pathways and cell cycle regulation, among others. Comparison of DNA methylation profiles between lung adenocarcinomas of current and never-smokers showed modest differences, identifying only LGALS4 as significantly hypermethylated and downregulated in smokers. LGALS4, encoding a galactoside-binding protein involved in cell-cell and cell-matrix interactions, was recently shown to be a tumor-suppressor in colorectal cancer. Unsupervised analysis of the DNA methylation data identified two tumor subgroups, one of which showed increased DNA methylation and was significantly associated with KRAS mutation and to a lesser extent, with smoking. Our analysis lays the groundwork for further molecular studies of lung adenocarcinoma by providing new candidate DNA methylation biomarkers for early detection, identifying novel molecular alterations potentially involved in lung adenocarcinoma development/progression, and describing an epigenetic subgroup of lung adenocarcinoma associated with KRAS mutation. 59 lung adenocarcinoma and 59 adjacent non-tumor lung tissue were macrodissected, bisulfite treated and analyzed on the Illumina Infinium HumanMethylation27K BeadChip

Dataset Information

Genome-scale analysis of aberrant DNA methylation in colorectal cancer

Publications

Genome-scale analysis of aberrant DNA methylation in colorectal cancer.

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