Altered patterns of hydroxymethylation regulate oncogenic pathways in pancreatic cancer
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE71839 | GEO | 2016/08/06
SECONDARY ACCESSION(S): PRJNA292300
REPOSITORIES: GEO
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Project description:Transcriptional deregulation of oncogenic pathways is a hallmark of cancer, and can be due to epigenetic alterations. 5-hydroxymethylcytosine is a recently discovered epigenetic modification that has not been studied in pancreatic cancer. Genome-wide analysis of 5-hmC enriched loci was conducted in low-passage pancreatic cancer cell lines and primary patient-derived xenografts and revealed strikingly altered patterns in neoplastic tissues. Differentially hydroxymethylated regions preferentially affected regulatory regions of the genome, specifically overlapping with H3K4me1 enhancers. Gain of 5-hmC was correlated with upregulation of the cognate transcripts, including many oncogenic pathways implicated in pancreatic neoplasia. Specifically, BRD4 was overexpressed and acquired 5hmC at enhancer regions in majority of neoplastic samples. Functionally, acquisition of 5hmC at BRD4 promoter regulated increase in transcript expression. Furthermore, blockade of BRD4 inhibited pancreatic cancer growth in vivo. In summary, redistribution of 5-hmC and preferential enrichment at oncogenic enhancers is a novel regulatory mechanism in human cancer. Genome-wide analysis of 5-hmC enriched loci was conducted in low-passage pancreatic cancer cell lines and primary patient-derived xenografts
2016-08-06 | E-GEOD-71839 | biostudies-arrayexpress
Project description:Transcriptional deregulation of oncogenic pathways is a hallmark of cancer, and can be due to epigenetic alterations. 5-hydroxymethylcytosine is a recently discovered epigenetic modification that has not been studied in pancreatic cancer. Genome-wide analysis of 5-hmC enriched loci with hmC-seal was conducted in low-passage pancreatic cancer cell lines and primary patient-derived xenografts and revealed strikingly altered patterns in neoplastic tissues. Differentially hydroxymethylated regions preferentially affected regulatory regions of the genome, specifically overlapping with known H3K4me1 enhancers. Furthermore, base pair resolution analysis of methylation and hydroxymethylation with oxidative bisulfite sequencing was conducted and correlated with chromatin accessibility by ATAC-seq in pancreatic cancer and control samples. 5hmC was specifically enriched at open regions of chromatin and gain of 5-hmC was correlated with upregulation of the cognate transcripts, including many oncogenic pathways implicated in pancreatic neoplasia, such as myc, KRAS, VEGF and BRD4. Specifically, BRD4 was overexpressed and acquired 5hmC at enhancer regions in majority of neoplastic samples. Functionally, acquisition of 5hmC at BRD4 promoter regulated increase in transcript expression. Furthermore, blockade of BRD4 inhibited pancreatic cancer growth in vivo. In summary, redistribution of 5-hmC and preferential enrichment at oncogenic enhancers is a novel regulatory mechanism in human cancer.
2017-09-14 | GSE97014 | GEO
Project description:Transcriptional deregulation of oncogenic pathways is a hallmark of cancer, and can be due to epigenetic alterations. 5-hydroxymethylcytosine is a recently discovered epigenetic modification that has not been studied in pancreatic cancer. Genome-wide analysis of 5-hmC enriched loci with hmC-seal was conducted in low-passage pancreatic cancer cell lines and primary patient-derived xenografts and revealed strikingly altered patterns in neoplastic tissues. Differentially hydroxymethylated regions preferentially affected regulatory regions of the genome, specifically overlapping with known H3K4me1 enhancers. Furthermore, base pair resolution analysis of methylation and hydroxymethylation with oxidative bisulfite sequencing was conducted and correlated with chromatin accessibility by ATAC-seq in pancreatic cancer and control samples. 5hmC was specifically enriched at open regions of chromatin and gain of 5-hmC was correlated with upregulation of the cognate transcripts, including many oncogenic pathways implicated in pancreatic neoplasia, such as myc, KRAS, VEGF and BRD4. Specifically, BRD4 was overexpressed and acquired 5hmC at enhancer regions in majority of neoplastic samples. Functionally, acquisition of 5hmC at BRD4 promoter regulated increase in transcript expression. Furthermore, blockade of BRD4 inhibited pancreatic cancer growth in vivo. In summary, redistribution of 5-hmC and preferential enrichment at oncogenic enhancers is a novel regulatory mechanism in human cancer.
2017-09-14 | GSE97008 | GEO
Project description:Transcriptional deregulation of oncogenic pathways is a hallmark of cancer, and can be due to epigenetic alterations. 5-hydroxymethylcytosine is a recently discovered epigenetic modification that has not been studied in pancreatic cancer. Genome-wide analysis of 5-hmC enriched loci with hmC-seal was conducted in low-passage pancreatic cancer cell lines and primary patient-derived xenografts and revealed strikingly altered patterns in neoplastic tissues. Differentially hydroxymethylated regions preferentially affected regulatory regions of the genome, specifically overlapping with known H3K4me1 enhancers. Furthermore, base pair resolution analysis of methylation and hydroxymethylation with oxidative bisulfite sequencing was conducted and correlated with chromatin accessibility by ATAC-seq in pancreatic cancer and control samples. 5hmC was specifically enriched at open regions of chromatin and gain of 5-hmC was correlated with upregulation of the cognate transcripts, including many oncogenic pathways implicated in pancreatic neoplasia, such as myc, KRAS, VEGF and BRD4. Specifically, BRD4 was overexpressed and acquired 5hmC at enhancer regions in majority of neoplastic samples. Functionally, acquisition of 5hmC at BRD4 promoter regulated increase in transcript expression. Furthermore, blockade of BRD4 inhibited pancreatic cancer growth in vivo. In summary, redistribution of 5-hmC and preferential enrichment at oncogenic enhancers is a novel regulatory mechanism in human cancer.
2017-09-14 | GSE97003 | GEO
Project description:Bromodomain-containing protein 4 (BRD4) functions as an epigenetic reader and binds to so-called super-enhancer regions of driving oncogenes such as MYC in cancer. We investigated the possibility to target super-enhancer regulated genes in neuroblastoma and in MYCN amplified disease in particular. We used OTX015, the first small-molecule BRD4 inhibitor to enter clinical phase I/II trials in adults, to test the feasibility to specifically target super-enhancer regulated gene-expression in neuroblastoma. BRD4 inhibition lead to significant transcriptional down-regulation of genes that were associated with super-enhancers, supporting the notion that BRD4 preferentially acts at these chromatin sites. BRD4 inhibition not only attenuated MYCN transcription but most significantly affected MYCN-regulated transcriptional programs.
2016-07-03 | E-MTAB-3672 | biostudies-arrayexpress
Project description:Chromatin regulators have become highly attractive targets for cancer therapy, yet many of these regulators are expressed in a broad range of healthy cells and contribute generally to gene expression. An important conundrum has thus emerged: how can inhibition of a general regulator of gene expression produce selective effects at specific oncogenes? Here we investigate how inhibition of the transcriptional coactivator BRD4 (Bromodomain containing 4) leads to selective inhibition of disease-critical oncogenes in a highly malignant blood cancer, multiple myeloma (MM). We found that BRD4 generally occupies the promoter elements of active genes together with the Mediator coactivator, but remarkably high levels of these two coactivator proteins were associated with a small set of exceptionally large enhancers. These super-enhancers are associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impact genes with super-enhancers, including the c-MYC oncogene. Super-enhancers were found at key oncogenic drivers in many other tumor cells. Thus, super-enhancers can regulate oncogenic drivers in tumor cells, which in some cells can be preferentially disrupted by BRD4 inhibition, which in turn contributes to the selective transcriptional effects observed at these oncogenes. These observations have implications for the discovery of novel cancer therapeutics directed at components of super-enhancers in diverse tumor types. ChIP-Seq for chromatin regulators and RNA Polymerase II in multiple myeloma, glioblastoma multiforme, and small cell lung cancer
2013-01-02 | E-GEOD-42355 | biostudies-arrayexpress
Project description:Chromatin regulators have become highly attractive targets for cancer therapy, yet many of these regulators are expressed in a broad range of healthy cells and contribute generally to gene expression. An important conundrum has thus emerged: how can inhibition of a general regulator of gene expression produce selective effects at specific oncogenes? Here we investigate how inhibition of the transcriptional coactivator BRD4 (Bromodomain containing 4) leads to selective inhibition of disease-critical oncogenes in a highly malignant blood cancer, multiple myeloma (MM). We found that BRD4 generally occupies the promoter elements of active genes together with the Mediator coactivator, but remarkably high levels of these two coactivator proteins were associated with a small set of exceptionally large enhancers. These super-enhancers are associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impact genes with super-enhancers, including the c-MYC oncogene. Super-enhancers were found at key oncogenic drivers in many other tumor cells. Thus, super-enhancers can regulate oncogenic drivers in tumor cells, which in some cells can be preferentially disrupted by BRD4 inhibition, which in turn contributes to the selective transcriptional effects observed at these oncogenes. These observations have implications for the discovery of novel cancer therapeutics directed at components of super-enhancers in diverse tumor types. Gene expression profiling in multiple myeloma cells after BET-Bromodomain inhibition with JQ1
2013-03-07 | E-GEOD-44929 | biostudies-arrayexpress
Project description:Background: 5-hydroxymethylcytosine (5-hmC) is a recently discovered epigenetic modification that is altered in cancers. Genome wide assays for 5-hmC determination are needed as many of the techniques commonly used to assay 5-methylcytosine (5-mC), including conventional methyl-sensitive restriction digest and bisulfite sequencing, are incapable of distinguishing between 5-mC and 5-hmC. Results: Glycosylation of 5-hmC residues by beta-Glucosyl Transferase (beta-GT) can make CCGG residues insensitive to digestion by MspI. We used this premise to modify the HELP-tagging assay to identify both 5-mC and 5-hmC loci in the genome. Comparison of sequencing libraries after HpaII, MspI and MspI+ beta-GT conversion resulted in locus specific 5-mC and 5-hmC determination. A custom bioinformatics pipeline was created to identify 5-hmC sites that were validated at global level by LS-MS and the locus specific level by qRT-PCR of 5-hmC pulldown DNA. Hydroxymethylation at both promoter and intragenic locations correlated positively with gene expression. Analysis of pancreatic cancer samples revealed striking redistribution of 5-hmC sites in cancer cells and demonstrated enrichment of this modification at many oncogenic promoters such as GATA6. Conclusions: The HELP-GT assay allows a high resolution, simultaneous determination of 5-hmC and 5-mC loci from small amounts of DNA with the utilisation of modest sequencing resources. Redistribution of 5-hmC seen in cancer highlights the importance of examining this modification in conjugation with conventional methylome analysis. We did methylation and hydroxymethylation tests for one control and two pancreatic cancer cases
2013-07-30 | E-GEOD-42723 | biostudies-arrayexpress
Project description:Ovarian cancer is one of the deadliest cancers among women worldwide and is the leading cause of gynecologic-related cancer deaths in the U.S. Enhancers are often repurposed by the tumor cells for the regulation of genes that allow tumor cells to become more aggressive and resistant to therapy. Recent evidence suggests that exploiting transcriptional dependence by targeting oncogenic super-enhancers may be a viable therapeutic avenue. To this end, we leveraged genomic data such as H3K27ac, BRD4, and copy number information to identify putatively oncogenic super-enhancers. We found that copy number amplification of these super-enhancers is predictive of clinical outcome and that the targets genes associated to the copy number events via chromatin eQTL analysis are involved in numerous oncogenic processes. To systematically probe the functions these super-enhancers we designed a CRISPR interference screen (dCas9-KRAB) so specifically inhibit each super-enhancer and measure the consequences on gene expression via RNA-seq. These results show pervasive gene expression changes that underlie the biology of ovarian cancer. Finally, we select two salient super-enhancers for further analysis. CRISPR-based deletion of these two super-enhancers results in in dramatic changes in gene expression and decreased cell proliferation of ovarian cancer cells. Taken together these analyses highlight the importance of BRD4-bound and copy number amplified super-enhancers in ovarian cancer oncogenic regulation.
2022-06-15 | GSE174256 | GEO
Project description:Ovarian cancer is one of the deadliest cancers among women worldwide and is the leading cause of gynecologic-related cancer deaths in the U.S. Enhancers are often repurposed by the tumor cells for the regulation of genes that allow tumor cells to become more aggressive and resistant to therapy. Recent evidence suggests that exploiting transcriptional dependence by targeting oncogenic super-enhancers may be a viable therapeutic avenue. To this end, we leveraged genomic data such as H3K27ac, BRD4, and copy number information to identify putatively oncogenic super-enhancers. We found that copy number amplification of these super-enhancers is predictive of clinical outcome and that the targets genes associated to the copy number events via chromatin eQTL analysis are involved in numerous oncogenic processes. To systematically probe the functions these super-enhancers we designed a CRISPR interference screen (dCas9-KRAB) so specifically inhibit each super-enhancer and measure the consequences on gene expression via RNA-seq. These results show pervasive gene expression changes that underlie the biology of ovarian cancer. Finally, we select two salient super-enhancers for further analysis. CRISPR-based deletion of these two super-enhancers results in in dramatic changes in gene expression and decreased cell proliferation of ovarian cancer cells. Taken together these analyses highlight the importance of BRD4-bound and copy number amplified super-enhancers in ovarian cancer oncogenic regulation.
2022-06-15 | GSE195677 | GEO