Landscape of G-quadruplex DNA structural regions in breast cancer
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ABSTRACT:
PROVIDER: PRJNA638648 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR11978000.fastq.gz | Fastqsanger.gz | |||
| SRR11978100.fastq.gz | Fastqsanger.gz | |||
| SRR11978200.fastq.gz | Fastqsanger.gz | |||
| SRR11978300.fastq.gz | Fastqsanger.gz | |||
| SRR11978400.fastq.gz | Fastqsanger.gz |
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Project description:Response and resistance to anticancer therapies vary due to inter- and intra-tumour heterogeneity. Here, we developed and applied a quantitative chromatin immunoprecipitation sequencing methodology to map differentially enriched G-quadruplex (G4) DNA structure-forming regions (∆G4Rs) in 22 breast cancer patient-derived tumour xenograft (PDTX) models. ∆G4Rs are significantly more associated with the promoter of highly amplified and expressed genes, and with somatic single-nucleotide variant mutations. Specific ∆G4Rs associate with certain patterns of breast cancer TF occupancy, revealing 7 distinct transcription factor programs with differential activities across PDTXs. Collectively, ∆G4Rs report on the genomic, transcriptomic and regulatory architecture of breast cancer. ∆G4R abundance and locations stratify PDTXs into at least three G4-based subtypes. ∆G4Rs of the majority of PDTXs (14/22) associated with more than one distinct breast cancer subtype, which we also call an integrative cluster (IC). This suggests the frequent coexistence of multiple breast cancer states within a PDTX model; the majority, in contrast to expectation, displaying aggressive triple-negative IC10. Short-term cultures of PDTX models with increased ∆G4R levels are more sensitive to small molecules targeting G4 DNA. Thus, G4 DNA structural landscapes revealed additional IC-related intra-tumour heterogeneity in PDTX biopsies, improving their cancer stratification and potentially new treatment strategies.
2020-06-11 | GSE152216 | GEO
Project description:The G-quadruplex is an alternative DNA structural motif that is considered to be functionally important in the mammalian genome. Herein, we address the hypothesis that G-quadruplex structures can exist within double-stranded genomic DNA using a G-quadruplex-specific probe. An engineered antibody is employed to enrich for DNA containing G-quadruplex structures, followed by deep sequencing to detect and map G-quadruplexes at high resolution in genomic DNA from human breast adenocarcinoma cells. Our high sensitivity structure-based pull-down strategy enables the isolation of genomic DNA fragments bearing a single as well as multiple G-quadruplex structures. Stable G-quadruplex structures are found in sub-telomeres, gene bodies and gene regulatory regions. For a sample of identified target genes, we show that G-quadruplex stabilizing ligands can modulate transcription. These results confirm the existence of G-quadruplex structures and their persistence in human genomic DNA. Four independent libraries have been enriched in DNA G-quadruplex structures using a G-quadruplex-specific probe. One genomic input library was sequenced as control. Deep-sequencing of these libraries allowed the mapping of G-quadruplexes on the genome.
2013-05-08 | E-GEOD-45241 | biostudies-arrayexpress
Project description:The G-quadruplex is an alternative DNA structural motif that is considered to be functionally important in the mammalian genome. Herein, we address the hypothesis that G-quadruplex structures can exist within double-stranded genomic DNA using a G-quadruplex-specific probe. An engineered antibody is employed to enrich for DNA containing G-quadruplex structures, followed by deep sequencing to detect and map G-quadruplexes at high resolution in genomic DNA from human breast adenocarcinoma cells. Our high sensitivity structure-based pull-down strategy enables the isolation of genomic DNA fragments bearing a single as well as multiple G-quadruplex structures. Stable G-quadruplex structures are found in sub-telomeres, gene bodies and gene regulatory regions. For a sample of identified target genes, we show that G-quadruplex stabilizing ligands can modulate transcription. These results confirm the existence of G-quadruplex structures and their persistence in human genomic DNA.
2013-05-08 | GSE45241 | GEO
Project description:DNA secondary structures are important for fundamental genome functions such as transcription and replication1. The G-quadruplex (G4) structural motif has been linked to gene regulation2,3 and genome instability4,5 and may be important to cancer development and other diseases6-8. Recently, ~700,000 discrete G4s have been observed in naked human single-stranded genomic DNA using G4-seq, a high-throughput sequencing technique that detects structural features in vitro.9 It is of vital importance to investigate G4 structures within an endogenous chromatin context, which until now remained elusive10,11. Herein, we address this via the development of G4 ChIP-seq, an antibody-based G4 chromatin immunoprecipitation and high-throughput sequencing approach. We identified ~10,000 endogenous G4 structures and show that G4s are predominantly seen in regulatory, nucleosome-depleted, chromatin regions. G4s were enriched in the promoters and 5âUTR regions of highly transcribed genes, particularly in genes related to cancer and in somatic copy number amplifications, such as MYC. Reorganization of the chromatin landscape using a histone deacetylase inhibitor, resulted in de novo G4 formation in new and more prominent regulatory, nucleosome-depleted regions associated with increased transcriptional output. Our findings suggest a striking relationship between promoter nucleosome-depleted regions, G4 formation and elevated transcriptional activity. Comparison between normal human epidermal keratinocytes and their immortalized counterparts revealed a ï¾7-fold greater G4 abundance in immortalized cells, of which 80 % were found in regulatory, nucleosome-depleted regions common to both cell types. Consequently, cells exhibiting more G4s displayed significantly increased transcriptional output and were more sensitive to growth inhibition by a small molecule G4 ligand. Overall, our results provide new mechanistic insights into where and when DNA adopts G4 structure in vivo. Our findings show for the first time that regulatory, nucleosome-depleted chromatin and transcriptional states predominantly shape the endogenous G4 DNA landscape. Two cell lines, treated with entinostat or untreated, analyzed to detect gene expression differences, presence of G-Qudruplexes and chromatin state. Each combination of conditions replicated in duplicates or triplicates.
2016-08-05 | E-GEOD-76688 | biostudies-arrayexpress
Project description:Chromosomal structural mutations play an important role in determining the transcriptional landscape of human breast cancers. To assess the nature of these structural mutations, we analyzed a representative sampling of the major types of breast tumor samples for detailed structural mutations using paired-end tag sequencing of long-insert genomic DNA (DNA-PET) with matched transcriptome ascertainment by RNA-seq. Compared with other structural mutations, tandem duplications are enriched around partners of fusion transcripts and demarcate regions of high gene expression. Moreover tandem duplications appear to be early events in tumor evolution by facilitating subsequent downstream amplification and deletion of important adjacent cancer associated genes. In a detailed reconstruction of events in chr17, we found large unpaired-inversions connect a duplicated ERBB2 with neighboring 17q21.3 amplicons while simultaneously deleting the intervening BRCA1 tumor suppressor locus. Using siRNAs in breast cancer cell lines, we showed that the 17q21.3 amplicon harbored a significant number of weak oncogenes that appeared consistently co-amplified in primary tumors. Down-regulation of BRCA1 expression augmented the cell proliferation in human normal mammary epithelial cells. Finally, using in silico approaches, we determined that genes whose expression in breast tumors are associated with either poor or good clinical prognosis appear clustered together in segments of frequent amplification or deletion, suggesting that structural abnormalities induce the loss or gain of blocks of adjacent genes with oncogenic or growth suppressor function. These analyses suggest that structural mutations efficiently orchestrate the gain and loss of cancer gene cassettes that engage many oncogenic pathways simultaneously. RNA sequencing of four primary breast cancer RNA samples (SOLiD, Applied Biosystems).
2014-07-01 | E-GEOD-57914 | biostudies-arrayexpress
Project description:Chromosomal structural mutations play an important role in determining the transcriptional landscape of human breast cancers. To assess the nature of these structural mutations, we analyzed a representative sampling of the major types of breast tumor samples for detailed structural mutations using paired-end tag sequencing of long-insert genomic DNA (DNA-PET) with matched transcriptome ascertainment by RNA-seq. Compared with other structural mutations, tandem duplications are enriched around partners of fusion transcripts and demarcate regions of high gene expression. Moreover tandem duplications appear to be early events in tumor evolution by facilitating subsequent downstream amplification and deletion of important adjacent cancer associated genes. In a detailed reconstruction of events in chr17, we found large unpaired-inversions connect a duplicated ERBB2 with neighboring 17q21.3 amplicons while simultaneously deleting the intervening BRCA1 tumor suppressor locus. Using siRNAs in breast cancer cell lines, we showed that the 17q21.3 amplicon harbored a significant number of weak oncogenes that appeared consistently co-amplified in primary tumors. Down-regulation of BRCA1 expression augmented the cell proliferation in human normal mammary epithelial cells. Finally, using in silico approaches, we determined that genes whose expression in breast tumors are associated with either poor or good clinical prognosis appear clustered together in segments of frequent amplification or deletion, suggesting that structural abnormalities induce the loss or gain of blocks of adjacent genes with oncogenic or growth suppressor function. These analyses suggest that structural mutations efficiently orchestrate the gain and loss of cancer gene cassettes that engage many oncogenic pathways simultaneously.
2014-07-01 | GSE57914 | GEO
Project description:It is generally thought that splicing factors regulate alternative splicing through binding to RNA consensus sequences. In addition to these linear motifs, RNA secondary structure is emerging as an important layer in splicing regulation. Here we demonstrate that RNA elements with G-quadruplex forming capacity promote exon inclusion. Destroying G-quadruplex forming capacity while keeping G-tracts intact abrogates exon inclusion. Analysis of RNA binding protein footprints revealed that G-quadruplexes are enriched in hnRNPF-binding sites and near hnRNPF-regulated alternatively spliced exons in the human transcriptome. Moreover, hnRNPF regulates an EMT-associated CD44 isoform switch in a G-quadruplex-dependent manner, which results in inhibition of EMT. Mining breast cancer TCGA datasets, we demonstrate that hnRNPF negatively correlates with an EMT gene signature and positively correlates with patient survival. These data suggest a critical role for RNA G-quadruplexes in regulating alternative splicing. Modulation of G-quadruplex structural integrity may control cellular processes important for tumor progression.
2018-01-22 | GSE107542 | GEO
Project description:G-quadruplex (G4) structural motifs have been linked to transcription, replication and genome instability and are implicated in cancer and other diseases. However, it is crucial to demonstrate the bona fide formation of G4 structures within an endogenous chromatin context. Herein we address this through the development of G4 ChIP-seq, an antibody-based G4 chromatin immunoprecipitation and high-throughput sequencing approach. We find ∼10,000 G4 structures in human chromatin, predominantly in regulatory, nucleosome-depleted regions. G4 structures are enriched in the promoters and 5' UTRs of highly transcribed genes, particularly in genes related to cancer and in somatic copy number amplifications, such as MYC. Strikingly, de novo and enhanced G4 formation are associated with increased transcriptional activity, as shown by HDAC inhibitor-induced chromatin relaxation and observed in immortalized as compared to normal cellular states. Our findings show that regulatory, nucleosome-depleted chromatin and elevated transcription shape the endogenous human G4 DNA landscape.
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Project description:G-quadruplex (G4) structures exist in single-stranded DNA of chromatins and regulate genome function. However, the native chromatin G4 landscape in living cells has yet to be fully characterized. Herein, we fused BG4 antibody and GFP-tag to construct a live-cell G4 identifier (LiveG4ID). We first displayed its function as a high-specificity chromatin G4 probe in living cells by Dox-induced expression LiveG4ID in HEK293T cells and detecting its cellular localization, biocompatibility and G4-binding specificity. By coupling LiveG4ID with CUT&Tag technology, we established LiveG4ID-seq, a method for mapping native chromatin G4 landscape in living cells. LiveG4ID-seq can identify more chromatin G4 motifs than traditional CUT&Tag and ChIP-seq methods. Using LiveG4ID-seq, we profiled the dynamic landscape of chromatin G4 structures during the cell cycle. These data demonstrate the capacity of LiveG4ID-seq to profile a more accurate G4 landscape in living cells and promote future study on chromatin G4 structures.
2022-01-15 | GSE193496 | GEO
Project description:Chromosomal structural mutations play an important role in determining the transcriptional landscape of human breast cancers. We determined that pro-oncogenic and anti-oncogenic genes are clustered throughout the genome and that these clusters coincide with regions of segmental amplification and deletion. We constructed detailed structural mutation maps of representative breast cancers and found that tandem duplications appear to nucleate regions for amplification. Subsequent rearrangements link distant pro-oncogenic elements for co-amplification, and are associated with loss of tumor suppressors. We show that genes engaged in co-amplifications or conjoint deletions on 17q and 8q have pro-growth effects that are additive in nature. Our results suggest structural mutations efficiently orchestrate the gain and loss of cancer gene cassettes that engage many oncogenic pathways simultaneously. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from fresh-frozen breast tumors with >80% tumor cell content and their paired peripheral blood samples. Copy number analysis of the SNP arrays was done using the copy number pipeline implemented into Partek software version 6.5
2013-06-29 | E-GEOD-48377 | biostudies-arrayexpress