Unknown,Transcriptomics,Genomics,Proteomics

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Epigenetically Silenced Genes Found Using Methylated DNA Immunoprecipitation in Colon Cancer Cells Deficient in DNMTs

ABSTRACT: CpG island promoter hypermethylation of tumor suppressor genes is a common hallmark of human cancer, and new large-scale epigenomic technologies might be useful in our attempts to define the complete DNA hypermethylome of tumor cells. Here we report a functional search for hypermethylated CpG islands using the colorectal cancer cell line HCT-116, in which two major DNA methyltransferases, DNMT1 and DNMT3b, have been genetically disrupted (DKOcells). Using methylated DNA immunoprecipitation (MeDIP) methodology in conjunction with promoter microarray analyses we found that DKO cells experience a significant loss of hypermethylated CpG islands. Further characterization of these candidate sequences demonstrates CpG island promoter hypermethylation and silencing of genes with potentially important roles in tumorigenesis, such as the Ras guanine-nucleotide release factor RASGRF2, the apoptosis-associated basic helixloop transcription factor BHLHB9, and the homeobox gene HOXD1. Hypermethylation of these genes occurs already in premalignant lesions and accumulates during tumorigenesis. Thus, our results demonstrate the usefulness of DNMT genetic disruption strategies combined with MeDIP in searching for unknown hypermethylated candidate genes in human cancer that might aid our understanding of the biology of the disease and be of potential translational use. Keywords: Human Proximal Promoter Array; DNA Methylation Comparative experiment: methylated DNA immunoprecipitated/INPUT(Total Genomic DNA) from the colon cancer cell line HCT116 wild type vs methylated DNA imonoprecipitated/INPUT from the colon cancer cell line HCT116 DNMT1/3b doubleknockout (DKO)

ORGANISM(S): Homo sapiens

SUBMITTER: Manel Esteller

PROVIDER: E-GEOD-9267 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Discovery of epigenetically silenced genes by methylated DNA immunoprecipitation in colon cancer cells.

Jacinto Filipe V FV Ballestar Esteban E Ropero Santiago S Esteller Manel M

Cancer research 20071201 24

CpG island promoter hypermethylation of tumor suppressor genes is a common hallmark of human cancer, and new large-scale epigenomic technologies might be useful in our attempts to define the complete DNA hypermethylome of tumor cells. Here, we report a functional search for hypermethylated CpG islands using the colorectal cancer cell line HCT-116, in which two major DNA methyltransferases, DNMT1 and DNMT3b, have been genetically disrupted (DKO cells). Using methylated DNA immunoprecipitation met ...[more]

PMID: 18089774

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Project description:This is one of expressional parts of the study. These data were correlated to epigenetic changes and CG density of genes in analyzed cells. The whole study has a following summary: To elucidate possible roles of DNA methylation and chromatin marks in transcription, we performed epigenetic profiling of chromosome 19 in human bronchial epithelial cells (HBEC) and in the colorectal cancer cell line HCT116 as well as its counterpart with double knockout of DNMT1 and DNMT3B (HCT116-DKO). We found that H3K9me3 forms intragenic chromatin blocks along genes with low CpG density in the gene body. Analysis of H3K36me3 profiles indicated that this mark associates either with active genes with low CpG density and H3K9me3 in the gene body or with active genes with high CpG density and DNA hypermethylation in the gene body. In HCT116 cells with double knockout of DNMT1 and DNMT3B, transcription of genes with low CpG density in the gene body was highly elevated and associated with promoter DNA demethylation and rearrangement of H3K9me3 and H3K36me3 occupation. Our finding suggests that similar to DNA methylation, H3K9me3 may play a role in intragenic gene regulation. Further, we observed that a combination of low CpG density in gene bodies together with H3K9me3 and H3K36me3 marking is a specific epigenetic feature of zinc finger (ZNF) genes, which comprise 90% of all genes carrying both histone marks on chromosome 19. For high CpG density genes, transcription and H3K36me3 occupancy were not changed in condition of partial or intensive loss of DNA methylation in gene bodies in the HCT116-DKO cell line. siRNA experiments with SETD2 knockdown in both HBEC and HCT116-DKO cell lines failed to reduce DNA methylation in gene bodies under conditions of H3K36me3 depletion. Our study suggests that the H3K36me3 and DNA methylation marks in gene bodies are established independently from each other and points to similar functional roles of intragenic DNA methylation and intragenic H3K9me3 for CpG-rich and CpG-poor genes, respectively. To elucidate how a loss of DNA methylation affects a gene expression and epigenome we studied colon cancer cell line HCT116 and its derivative, HCT116 DNMT1-/- DNMT3b -/- (HCT116-DKO). According to previous studies HCT116-DKO is characterized by 95% of loss of DNA methylation. In HCT116 and HCT116-DKO cells, we profiled diverse epigenetic marks and gene expression. Further a crosstalk between epigenetic changes and transcriptional changes was analyzed. This is the expressional part of study.

Project description:Cancer is characterised by DNA hypermethylation and gene silencing of CpG island-associated promoters, including tumour suppressor genes The methyl-CpG-binding domain (MBD) family of proteins bind to methylated DNA and can aid in the meditation of gene silencing by interaction with histone deacetylases and histone methyltransferases. However the mechanisms responsible for eliciting CpG island hypermethylation in cancer, and the potential role that MBD may proteins play in modulation of the methylome remain unclear. Our previous work demonstrated that MBD2 preferentially binds to the hypermethylated GSTP1 promoter CpG island in prostate cancer cells. Here, we use functional genetic approaches to investigate if MBD2 plays an active role in promoting DNA methylation. First, we show that loss of MBD2 results in inhibition of both maintenance and spread of de novo methylation of a transfected construct containing the GSTP1 promoter CpG island in prostate cancer cells and Mbd2-/- mouse fibroblasts. De novo methylation was rescued by transient expression of Mbd2 in Mbd2-/- cells. Second, we show that MBD2 depletion triggers significant hypomethylation genome-wide in prostate cancer cells with concomitant loss of MBD2 binding at promoter and enhancer regulatory regions. Finally, CpG islands and shores that become hypomethylated after MBD2 depletion in LNCaP cancer cells show significant hypermethylation in clinical prostate cancer, highlighting a potential active role of MBD2 in promoting cancer specific hypermethylation. Importantly, co-immunoprecipiation of MBD2 reveals that MBD2 associates with DNA methyltransferase (DNMT) enzymes 1 and 3A. Together our results demonstrate that MBD2 plays a critical role in â??rewritingâ?? the cancer methylome at specific regulatory regions. LNCaP prostate cancer cell line clones with reduced MBD2 expression were establised by using shRNA to MBD2 and scrambled control clones were established with scrambled control shRNA. To interrogate methylation changes induced by MBD2 knock-down we profiled three stably transfected scrambled control clones and three MBD2 knockdown clones on Illumina HumanMethylation450K arrays. Differential methylation analysis was carried out to identified CpG sites hypo-/hyper-methylated as a result of MBD2 knockdown.

Project description:Cancer is characterised by DNA hypermethylation and gene silencing of CpG island-associated promoters, including tumour suppressor genes The methyl-CpG-binding domain (MBD) family of proteins bind to methylated DNA and can aid in the meditation of gene silencing by interaction with histone deacetylases and histone methyltransferases. However the mechanisms responsible for eliciting CpG island hypermethylation in cancer, and the potential role that MBD may proteins play in modulation of the methylome remain unclear. Our previous work demonstrated that MBD2 preferentially binds to the hypermethylated GSTP1 promoter CpG island in prostate cancer cells. Here, we use functional genetic approaches to investigate if MBD2 plays an active role in promoting DNA methylation. First, we show that loss of MBD2 results in inhibition of both maintenance and spread of de novo methylation of a transfected construct containing the GSTP1 promoter CpG island in prostate cancer cells and Mbd2-/- mouse fibroblasts. De novo methylation was rescued by transient expression of Mbd2 in Mbd2-/- cells. Second, we show that MBD2 depletion triggers significant hypomethylation genome-wide in prostate cancer cells with concomitant loss of MBD2 binding at promoter and enhancer regulatory regions. Finally, CpG islands and shores that become hypomethylated after MBD2 depletion in LNCaP cancer cells show significant hypermethylation in clinical prostate cancer, highlighting a potential active role of MBD2 in promoting cancer specific hypermethylation. Importantly, co-immunoprecipiation of MBD2 reveals that MBD2 associates with DNA methyltransferase (DNMT) enzymes 1 and 3A. Together our results demonstrate that MBD2 plays a critical role in ârewritingâ the cancer methylome at specific regulatory regions. LNCaP prostate cancer cell line clones with reduced MBD2 expression were establised by using shRNA to MBD2 and scrambled control clones were established with scrambled control shRNA. To interrogate expression changes induced by MBD2 knock-down we profiled three stably transfected scrambled control clones and three MBD2 knockdown clones on Affymetrix HuGene 1.0ST expression arrays. Differential expression analysis was carried out to identified genes up-/down-regulated by MBD2 knockdown.

Project description:This is one of expressional parts of the study. These data were correlated to epigenetic marks and CG density of genes in analyzed cells. The whole study has a following summary: To elucidate possible roles of DNA methylation and chromatin marks in transcription, we performed epigenetic profiling of chromosome 19 in human bronchial epithelial cells (HBEC) and in the colorectal cancer cell line HCT116 as well as its counterpart with double knockout of DNMT1 and DNMT3B (HCT116-DKO). We found that H3K9me3 forms intragenic chromatin blocks along genes with low CpG density in the gene body. Analysis of H3K36me3 profiles indicated that this mark associates either with active genes with low CpG density and H3K9me3 in the gene body or with active genes with high CpG density and DNA hypermethylation in the gene body. In HCT116 cells with double knockout of DNMT1 and DNMT3B, transcription of genes with low CpG density in the gene body was highly elevated and associated with promoter DNA demethylation and rearrangement of H3K9me3 and H3K36me3 occupation. Our finding suggests that similar to DNA methylation, H3K9me3 may play a role in intragenic gene regulation. Further, we observed that a combination of low CpG density in gene bodies together with H3K9me3 and H3K36me3 marking is a specific epigenetic feature of zinc finger (ZNF) genes, which comprise 90% of all genes carrying both histone marks on chromosome 19. For high CpG density genes, transcription and H3K36me3 occupancy were not changed in condition of partial or intensive loss of DNA methylation in gene bodies in the HCT116-DKO cell line. siRNA experiments with SETD2 knockdown in both HBEC and HCT116-DKO cell lines failed to reduce DNA methylation in gene bodies under conditions of H3K36me3 depletion. Our study suggests that the H3K36me3 and DNA methylation marks in gene bodies are established independently from each other and points to similar functional roles of intragenic DNA methylation and intragenic H3K9me3 for CpG-rich and CpG-poor genes, respectively. Expressional changes associated with SETD2 siRNA transfection in HBEC Compare siRNA vs. control

Dataset Information

Epigenetically Silenced Genes Found Using Methylated DNA Immunoprecipitation in Colon Cancer Cells Deficient in DNMTs

Publications

Discovery of epigenetically silenced genes by methylated DNA immunoprecipitation in colon cancer cells.

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