5-hydroxymethylcytosine marks promoters in colon that resist hypermethylation in cancer
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Silvia Halim
PROVIDER: E-GEOD-47592 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:The discovery of cytosine hydroxymethylation (5-hmC) as a mechanism that potentially controls DNA methylation changes typical of neoplasia prompted us to investigate its behavior in colon cancer. 5-hmC is globally reduced in proliferating cells such as colon tumors and the gut crypt progenitors, from which tumors can arise. Here, we show that colorectal tumors and cancer cells express Ten-Eleven Translocation (TET) transcripts at levels similar to normal tissues. Genome-wide analyses show that promoters marked by 5-hmC in normal tissue, and those identified as TET2 targets in colorectal cancer cells, are resistant to methylation gain in cancer. In vitro studies of TET2 in cancer cells confirm that these promoters are resistant to methylation gain independently of sustained TET2 expression. We also find that a considerable number of the methylation gain-resistant promoters marked by 5-hmC in normal colon overlap with those that are marked with poised bivalent histone modifications in embryonic stem cells. Together our results indicate that promoters that acquire 5-hmC upon normal colon differentiation are innately resistant to neoplastic hypermethylation by mechanisms that do not require high levels of 5-hmC in tumors. Our study highlights the potential of cytosine modifications as biomarkers of cancerous cell proliferation. Six samples were analyzed. 2 biological replicates each of HCT116 cells stably transfected with an empty vector control (TET_KD_Plk), with shRNA to TET2 (TET_KD_2C) and with shRNA to TET2 and TET3 (TET_KD_2.3)
2015-02-03 | E-GEOD-63421 | biostudies-arrayexpress
Project description:Breast cancer is a molecularly, biologically and clinically heterogeneous group of disorders. Understanding this diversity is essential to improving diagnosis and optimising treatment. Both genetic and acquired epigenetic abnormalities participate in cancer, but information is scant on the involvement of the epigenome in breast cancer and its contribution to the complexity of the disease. Here we used the Infinium Methylation Platform to profile at single-CpG resolution (over 14,000 genes interrogated) the methylomes of 119 breast tumours. It emerges that many genes whose expression is linked to the ER status are epigenetically controlled (or/ we show that the two major phenotypes of breast cancers determined by ER status are widely involving epigenetic regulatory mechanisms), offering the prospect of a novel approach to treating ER-positive tumours. We have distinguished methylation-profile-based tumour clusters, some coinciding with known “expression subtypes” but also new entities that may provide a meaningful basis for refining breast tumour typology. We show that methylation patterns may reflect the cellular origins of tumours. Having highlighted an unexpectedly strong epigenetic component in the regulation of key immune pathways, we show that a set of immune genes have high prognostic value in specific tumour categories. By laying the ground for better understanding of breast cancer heterogeneity and improved tumour taxonomy, the precise epigenetic portraits drawn here should contribute to better management of breast cancer patients. 6 methylation profiling of HCT116 cell lines. Study of epigenetic variation (methylation) linked to gene expression. No replicate, no reference sample.
2011-10-18 | E-GEOD-20868 | biostudies-arrayexpress
Project description:Global patterns of DNA methylation, mediated by the DNA methyltransferases (DNMTs), are disrupted in all cancers by mechanisms that remain largely unknown, hampering their development as therapeutic targets. Combinatorial acute depletion of all DNMTs in a pluripotent human tumor cell line, followed by epigenome and transcriptome analysis, revealed DNMT functions in unprecedented detail. DNMT3B occupancy regulates methylation during differentiation, while an unexpected interplay was discovered in which DNMT1 and DNMT3B antithetically regulate methylation and hydroxymethylation in gene bodies, a finding confirmed in other cell types. DNMT3B mediated nonCpG methylation, while DNMT3L influenced the activity of DNMT3B toward nonCpG versus CpG site methylation. Taken together, these data reveal new functional targets of each DNMT suggesting that isoform selective inhibition would be therapeutically advantageous. Overall, 27 samples were analyzed using the Infinium HumanMethylation450 BeadChip. 19 samples include NCCIT cells treated with various siRNAs targeting specific DNA methyltransferases. For the samples labeled biological replicate 1, NTC-1 serves as the control. Two additional biological replicates were analyzed for the siDNMT1, siDNMT3B, and si3B+3L condition; NTC-2 serves as the control for these samples. Six samples include HCT116 WT and various derivatives with alternative expression of DNMT1 and/or DNMT3B; WT serves as the control. Two samples include the undifferentiated (UD) and 7-day differentiated (DF) NCCIT cells; UD serves as the control.
2014-10-20 | E-GEOD-54840 | biostudies-arrayexpress
Project description:Background: Low birth weight is associated with an increased adult metabolic disease risk. It is widely discussed that poor intrauterine conditions could induce long-lasting epigenetic modifications, leading to systemic changes in regulation of metabolic genes. In a unique cohort of 17 monozygotic (MZ) monochorionic female twins very discordant for birth weight (relative differences ranging from 21.3-35.7%), we examined if adverse prenatal growth conditions experienced by the smaller co-twins lead to systemic long-lasting DNA methylation changes. Genome-wide DNA methylation profiles were acquired from saliva DNA using the Infinium HumanMethylation450 BeadChip, targeting ~2% of all CpGs in the genome. Results: Overall, co-twins showed very similar genome-wide DNA methylation profiles. Since observed differences were almost exclusively caused by variable cellular composition, an original marker-based adjustment strategy was developed to eliminate such variation at affected CpGs. Among adjusted and unchanged CpGs 3153 were differentially methylated between the heavy and light co-twins at nominal significance (p<0.01), of which 45 showed absolute mean β-value differences >0.05 (max=0.08). Deep bisulfite sequencing of eight such loci revealed that differences remained in the range of technical variation, arguing against a reproducible biological effect. Analysis of methylation in repetitive elements using methylation-dependent primer extension assays also indicated no significant intra-pair differences. Conclusions: Severe intrauterine growth differences observed within these MZ twins are not associated with long-lasting DNA methylation differences in cells composing saliva, detectable with up-to-date technologies. Additionally, our results indicate that uneven cell type composition can lead to spurious results and should be addressed in epigenomic studies. DNA methylation profiles of saliva from 17 Adult Female MZ MC Twins discordant for birth weight.
2013-05-13 | E-GEOD-39560 | biostudies-arrayexpress
Project description:Genome wide DNA methylation profiling of normal and breast cancer samples. The Illumina Infinium 450k Human DNA methylation Beadchip v1.1 was used to obtain DNA methylation profiles across approximately 485577 CpGs in breast cancer and normal samples. Samples included 40 normal, 80 breast cancer samples. Bisulphite converted DNA from the 120 samples were hybridised to the Illumina Infinium 450k Human Methylation Beadchip v1.1
2015-03-11 | E-GEOD-66695 | biostudies-arrayexpress
Project description:Genome wide DNA methylation profiling of DNA from K562 cells treated with three commonly used pesticides and control (EtOH). The Illumina Infinium 27k Human DNA methylation Beadchip was used to obtain DNA methylation profiles across approximately 27,000 CpGs in DNA samples. Bisulphite converted DNA from the samples were hybridised to the Illumina Infinium 27k Human Methylation Beadchip. 7 pesticides were used.
2012-06-13 | E-GEOD-38646 | biostudies-arrayexpress
Project description:Down syndrome is characterized by a wide spectrum of clinical signs, which include cognitive and endocrine disorders and haematological abnormalities. Although it is well established that the causative defect of Down syndrome is the trisomy of chromosome 21, the molecular bases of Down syndrome phenotype are still largely unknown. We used the Infinium HumanMethylation450 BeadChip to investigate DNA methylation patterns in whole blood from 29 subjects affected by Down syndrome (DS), using their healthy relatives as controls (mothers and unaffected siblings). This family-based model allowed us to monitor possible confounding effects on DNA methylation patterns deriving from genetic and environmental (lifestyle) factors. The identified epigenetic signature of Down syndrome includes differentially methylated regions that, although enriched on chromosome 21, interest most of the other chromosomes and can be functionally linked to the developmental and haematological defects characteristic of the disease. DNA was extracted from whole peripheral blood using the QIAamp 96 DNA Blood Kit (QIAGEN) and quantified by Quant-iT™ PicoGreen (Invitrogen). Sodium bisulphite conversion of 500 ng of each sample was performed using the EZDNA Methylation-Gold Kit according to the manufacturer's recommendation for Illumina Infinium Assay. 4 ul of bisulfite converted DNA were hybridized on Infinium HumanMethylation 450 BeadChip, following manufacturer’s instructions. Arrays were scanned by HiScan SQ scanner (Illumina) and the intensities of the images were extracted using GenomeStudio (2010.3) Methylation module (1.8.5) software. Methylation levels of each CpG is reported as beta value.
2015-03-03 | E-GEOD-52588 | biostudies-arrayexpress
Project description:PURPOSE: Non-small cell lung cancers (NSCLC) comprise multiple distinct biological groups with different prognoses. For example, patients with epithelial-like (EL) tumors have a better prognosis and exhibit greater sensitivity to inhibitors of the epidermal growth factor receptor (EGFR) pathway than patients with mesenchymal-like (ML) tumors. Here we test the hypothesis that EL NSCLCs can be distinguished from ML NSCLCs on the basis of global DNA methylation patterns. EXPERIMENTAL DESIGN: To determine whether phenotypic subsets of NSCLC can be defined based on their DNA methylation patterns, we combined microfluidics-based gene expression analysis and genome-wide methylation profiling. We derived robust classifiers for both gene expression and methylation in cell lines and tested these classifiers in surgically resected NSCLC tumors. We validate our approach using quantitative RT-PCR and methylation specific PCR in formalin-fixed biopsies from NSCLC patients who went on to fail front-line chemotherapy. RESULTS: We show that patterns of methylation divide NSCLCs into EL and ML subsets as defined by gene expression and that these signatures are similarly correlated in NSCLC cell lines and tumors. We identify multiple DMRs, including ERBB2 and ZEB2, whose methylation status is strongly associated with an epithelial phenotype in NSCLC cell lines, surgically resected tumors, and formalin-fixed biopsies from NSCLC patients who went on to fail front-line chemotherapy. CONCLUSIONS: Our data demonstrate that patterns of DNA methylation can divide NSCLCs into two phenotypically distinct subtypes of tumors and provide proof of principle that differences in DNA methylation can be used for predictive biomarker discovery and development. To determine whether phenotypic subsets of NSCLC can be defined based on their DNA methylation patterns, we combined microfluidics-based gene expression analysis and genome-wide methylation profiling. We derived robust classifiers for both gene expression and methylation in cell lines and tested these classifiers in surgically resected NSCLC tumors. We validate our approach using quantitative RT-PCR and methylation specific PCR in formalin-fixed biopsies from NSCLC patients who went on to fail front-line chemotherapy.
2012-03-03 | E-GEOD-36216 | biostudies-arrayexpress
Project description:Background: In vitro models are an essential tool towards understanding the molecular characteristics of colorectal cancer (CRC) and the testing of therapies for CRC. To this end we established 21 novel CRC cell lines of which six were derived from liver metastases. Extensive genetic, genomic, transcriptomic and methylomic profiling was performed in order to characterize these new cell lines and all data is made publically available. Additionally, sensitivity of oxaliplatin was tested as a measure for chemotherapy resistance. Results: DNA copy-number alterations (CNA) were compared between primary and metastasis derived cell lines. In concordance with previous studies copy-number gain of chr20, and loss of chr8p were found highly specific for liver metastases. Previously reported BRAF-mutation associated DNA methylation profiles could be validated on the genome-wide DNA methylation profiles of these cell lines. 47.6% of the loci previously reported to associate with BRAF mutation status were reproduced in this dataset. When examining the gene expression profiles in conjunction with these DNA methylation results, we identified 20 genes of which the gene expression correlated with the DNA methylation status, including MEIS1, LRAT and STC2. These genes have previously been reported to be subject to transcriptional regulation through DNA hypermethylation, validating our approach. Conclusions: By combining mutation profiles with CNA and gene expression profiles we constructed an overview of the alterations in the major CRC-related signalling pathways. The mutation profiles, along with the genome, transcriptome and methylome data of these cell lines will be made publically available . This combined dataset puts these cell lines among the best characterized CRC cell lines, allowing researchers to select appropriate cell line models for their particular experiment, making optimal use of these novel cell lines as in vitro model for CRC. 21 CRC cell lines were analyzed
2016-02-29 | E-GEOD-67772 | biostudies-arrayexpress
Project description:Gene expression is regulated by genetic variants and DNA methylation with evidence from molecular biology studies, as well as expression QTL (eQTL) mapping and methylation QTL (mQTL) mapping. In this study, we explored the interaction between genetic variants and DNA methylation for its influence on gene expression. We analyzed a postmortem brain data and identified 2,768 SNP-methylation interaction (SMI) that can survive Bonferroni correction for the number of tests in cis- region of each gene. Seven SNP-methylation pairs were significant after Bonferroni correction for all the tests, including number of gene expression traits, we performed in this study. Only a small proportion of the SMI had evidence from the exact same SNP-transcript pair in eQTL mapping or SNP-methylation pair in mQTL mapping. This suggested that the interaction analysis could uncover novel regulatory relationships, which would be missed by eQTL or mQTL analyses. Since methylation per se is regulated by both genetic and environmental factors, analysis indicates that the SMI detected in this study may involve both genetic and environmental regulation. A total of 155 postmortem cerebellum brains were used in this study, including 47 bipolar disorder, 46 schizophrenia, 15 depression patients and 47 normal controls. All were of European Ancestry. We also designed 13 random replicates in our experiment. Illumina Infinium HumanMethylation27 BeadChip was used for DNA methylation profiling. The assay was performed at the Genomics Core Facility at Northwestern University.
2013-06-30 | E-GEOD-38873 | biostudies-arrayexpress