Integrated analysis of genomic and epigenomic regulation of transcriptome identifies molecular subtypes of liver cancer (gene expression)
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE87630 | GEO | 2017/10/05
SECONDARY ACCESSION(S): PRJNA345436
REPOSITORIES: GEO
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Project description:We assessed DNA methylation and copy number status of 27,000 CpGs in 149 urothelial carcinomas and integrated the findings with gene expression and mutation data. Methylation was associated with gene expression for 1,332 CpGs, of which 26% showed positive correlation with expression, i.e., high methylation and high gene expression levels. These positively correlated CpGs were part of specific transcription factor binding sites, such as sites for MYC and CREBP1, or located in gene bodies. Furthermore, we found genes with copy number gains, low expression and high methylation levels, revealing an association between methylation and copy number levels. This phenomenon was typically observed for developmental genes, such as HOX genes and tumor suppressor genes. In contrast, we also identified genes with copy number gains, high expression and low methylation levels. This was for instance observed for some keratin genes. Tumor cases could be grouped into four subgroups, termed epitypes, by their DNA methylation profiles. One epitype was influenced by the presence of infiltrating immune cells, two epitypes were mainly composed of non-muscle invasive tumors, and the remaining epitype of muscle invasive tumors. The polycomb complex protein EZH2 that blocks differentiation in embryonic stem cells showed increased expression both at the mRNA and protein levels in the muscle invasive epitype, together with methylation of polycomb target genes and HOX genes. Our data highlights HOX gene silencing and EZH2 expression as mechanisms to promote a more undifferentiated and aggressive state in UC.
2012-08-31 | GSE33510 | GEO
Project description:Epigenetic dysregulation is a universal feature of cancer that results in altered patterns of gene expression that drive malignancy. Brain tumors exhibit subtype-specific epigenetic alterations, however the molecular mechanisms responsible for these diverse epigenetic states remain unclear. Here we show that the developmental transcription factor Sox9 differentially regulates epigenomic states in high-grade glioma (HGG) and ependymoma (EPN). These contrasting roles for Sox9 correspond with protein interactions with histone deacetylating complexes in HGG, and association with the Rela oncofusion in EPN. Together, our studies demonstrate how epigenomic states are differentially regulated in distinct subtypes of brain tumors, while revealing divergent roles for Sox9 in HGG and EPN tumorigenesis.
2022-07-13 | PXD033863 | Pride
Project description:We assessed DNA methylation and copy number status of 27,000 CpGs in 149 urothelial carcinomas and integrated the findings with gene expression and mutation data. Methylation was associated with gene expression for 1,332 CpGs, of which 26% showed positive correlation with expression, i.e., high methylation and high gene expression levels. These positively correlated CpGs were part of specific transcription factor binding sites, such as sites for MYC and CREBP1, or located in gene bodies. Furthermore, we found genes with copy number gains, low expression and high methylation levels, revealing an association between methylation and copy number levels. This phenomenon was typically observed for developmental genes, such as HOX genes and tumor suppressor genes. In contrast, we also identified genes with copy number gains, high expression and low methylation levels. This was for instance observed for some keratin genes. Tumor cases could be grouped into four subgroups, termed epitypes, by their DNA methylation profiles. One epitype was influenced by the presence of infiltrating immune cells, two epitypes were mainly composed of non-muscle invasive tumors, and the remaining epitype of muscle invasive tumors. The polycomb complex protein EZH2 that blocks differentiation in embryonic stem cells showed increased expression both at the mRNA and protein levels in the muscle invasive epitype, together with methylation of polycomb target genes and HOX genes. Our data highlights HOX gene silencing and EZH2 expression as mechanisms to promote a more undifferentiated and aggressive state in UC. The study was conducted on genomic DNA from 150 primary fresh-frozen urothelial carcinoma tumors selected to have equal representation of stages Ta, T1 and T2>. The design also included four fully methylated and four unmethylated hybridization controls as well as 7 Normal urothelium samples. One tumor sample (UC_0556_1) was included as a technical replicate in each of four bisulfite treatment batches. The samples were bisulfite treated and hybridized to Illumina Human Methylation27 Bead Chip arrays according to manufacturers instructions at the SCIBLU Genomics Centre at Lund University, Sweden. Note: Illumina methylation data set comprises total of 168 samples (raw data), but 156 samples (processed data), derived from primary urothelial carcinoma samples. See README.txt for details of the 12 samples not included in the final, processed data.
2012-08-31 | E-GEOD-33510 | biostudies-arrayexpress
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Project description:The heterotic hybrid offspring of Arabidopsis accessions C24 and Landsberg erecta have altered methylomes. Changes occur most frequently at loci where parental methylation levels are different. There are context-specific biases in the non-additive methylation patterns with mCG generally increased and mCHH decreased relative to the parents. These changes are a result of two main mechanisms, Trans Chromosomal Methylation (TCM) and Trans Chromosomal deMethylation (TCdM), where the methylation level of one parental allele alters to resemble that of the other parent. Regions of altered methylation are enriched around genic regions and are often correlated with changes in siRNA levels. We identified examples of genes with altered expression likely to be due to methylation changes and suggest that in crosses between the C24 and Ler accessions, epigenetic controls can be important in the generation of altered transcription levels which may contribute to the increased biomass of the hybrids. C24, Ler, and C24 x Ler
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Project description:X chromosome inactivation (XCI) is a dosage compensation mechanism that silences the majority of genes on one X chromosome in each female cell. In order to characterize epigenetic changes that accompany this process, we measured DNA methylation levels in both 45,X Turner syndrome patients, who carry a single active X chromosome (Xa) and normal 46,XX females, who carry one Xa and one inactive X (Xi). Methylated DNA was immunoprecipitated and hybridized to tiling oligonucleotide arrays, generating epigenetic profiles of active and inactive X chromosomes. We observed that XCI is accompanied by changes in DNA methylation specifically at CpG islands. While the majority of CpG islands show increased methylation levels on the Xi, XCI results in reduced methylation at ~20% of CpG islands. Both intra- and inter-genic CpG islands are epigenetically modified, with the biggest increase in methylation occuring at the promoters of genes silenced by XCI. In contrast, genes escaping XCI have low levels of promoter methylation, while genes that undergo polymorphic silencing show intermediate increases in methylation proportionate to their frequency of inactivation. Thus promoter methylation and susceptibility to XCI are correlated. We observed a global correlation between CpG island methylation and the evolutionary age of different X chromosome strata, and that genes escaping XCI show increased methylation within gene bodies. We utilized our epigenetic map to predict both novel genes escaping XCI, and to identify sequence features that may contribute to the XCI process. Finally, as our study included Turner syndrome patients with single X chromosomes of both maternal and paternal origin we searched for parent-of-origin specific methylation differences, but found no evidence to support imprinting on the human X chromosome. Our study provides the first epigenetic profile of active and inactive X chromosomes, giving novel insights into the phenomenon of dosage compensation. Methylated DNA was enriched by immunoprecipitation using antibodies against 5-methylcytosine. meDIP and input DNA was labeled with cy5 and cy3 respectively and hybridized to Nimblegen arrays comprising 2.1 million 50-85mers covering human chromosomes 20, 21, 22, X and Y at a mean density of ~1 probe per 100bp. Resulting log2 fluorescence ratios correspond to methylation levels. Seven patients with Turner syndrome (45,X karyotype), and three normal females (46,XX karyotype) were analyzed. Of the Turner syndrome cases, four had a maternally-derived X, and three had a paternally-derived X chromosome.
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