Integrated analysis of extrachromosomal DNA elements in SCLC [scCNV]
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE206352 | GEO | 2023/01/24
REPOSITORIES: GEO
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Project description:Integrated analysis of whole-genome sequencing, long-range optical mapping, single-cell DNA sequencing, and fluorescence in situ hybridization to find extrachromosomal DNA (ecDNA) as the primary source of MYC amplifications and driver fusions in SCLC. ecDNAs bring to proximity enhancer elements and oncogenes through circularization, creating transcription-amplifying units, driving heterogeneity of MYC gene dosage and expression of SCLC lineage-defining transcription factors.
2023-01-24 | GSE206351 | GEO
Project description:Integrated analysis of whole-genome sequencing, long-range optical mapping, single-cell DNA sequencing, and fluorescence in situ hybridization to find extrachromosomal DNA (ecDNA) as the primary source of MYC amplifications and driver fusions in SCLC. ecDNAs bring to proximity enhancer elements and oncogenes through circularization, creating transcription-amplifying units, driving heterogeneity of MYC gene dosage and expression of SCLC lineage-defining transcription factors.
2023-01-24 | GSE206353 | GEO
Project description:Oncogene amplification on extrachromosomal DNA (ecDNA) is a pervasive driver event in cancer, yet our understanding of how ecDNA forms is limited. Here, we couple a CRISPR-based method for ecDNA induction with extensive characterization of newly formed ecDNA to examine their biogenesis. We find that DNA circularization is efficient, irrespective of 3D genome context, with formation of 800kb, 1 Mb, and 1.8 Mb ecDNAs reaching or exceeding 15%. We show non-homologous end joining and microhomology-mediated end joining both contribute to ecDNA formation, while inhibition of DNA-PKcs and ATM have opposing impacts on ecDNA formation. EcDNA and the corresponding chromosomal excision scar can form at significantly different rates and respond differently to DNA-PKcs and ATM inhibition. Taken together, our results support a model of ecDNA formation in which double strand break ends dissociate from their legitimate ligation partners prior to joining of illegitimate ends to form the ecDNA and excision scar.
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Project description:Focal gene amplifications are among the most common cancer-associated mutations, but their evolution and contribution to tumorigenesis have proven challenging to recapitulate in primary cells and model organisms. Here we describe a general strategy to engineer large (>1 Mbp) focal amplifications mediated by extrachromosomal circular DNAs (ecDNAs) in a spatiotemporally controlled manner in cells and in genetically engineered mice. By coupling ecDNA formation with expression of selectable markers, we track the dynamics of ecDNA-containing cells under physiological conditions and in the presence of specific selective pressures. We also apply this approach to generate mice harboring Cre-inducible Myc- and Mdm2-containing ecDNAs analogous to those occurring in human cancers. We show that the engineered ecDNAs spontaneously accumulate in primary cells derived from these animals, promoting their proliferation, immortalization, and transformation. Finally, we demonstrate the ability of Mdm2-containing ecDNAs to promote tumor formation in an autochthonous mouse model of hepatocellular carcinoma.
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Project description:Focal gene amplifications are among the most common cancer-associated mutations, but their evolution and contribution to tumorigenesis have proven challenging to recapitulate in primary cells and model organisms. Here we describe a general strategy to engineer large (>1 Mbp) focal amplifications mediated by extrachromosomal circular DNAs (ecDNAs) in a spatiotemporally controlled manner in cells and in genetically engineered mice. By coupling ecDNA formation with expression of selectable markers, we track the dynamics of ecDNA-containing cells under physiological conditions and in the presence of specific selective pressures. We also apply this approach to generate mice harboring Cre-inducible Myc- and Mdm2-containing ecDNAs analogous to those occurring in human cancers. We show that the engineered ecDNAs spontaneously accumulate in primary cells derived from these animals, promoting their proliferation, immortalization, and transformation. Finally, we demonstrate the ability of Mdm2-containing ecDNAs to promote tumor formation in an autochthonous mouse model of hepatocellular carcinoma.
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Project description:Extrachromosomal, circular DNA (ecDNA) is emerging as a prevalent yet less characterized oncogenic alteration in cancer genomes. We leverage ChIA-PET and ChIA-Drop chromatin interaction assays to characterize genome-wide ecDNA-mediated chromatin contacts that impact transcriptional programs in cancers. ecDNAs in glioblastoma patient-derived neurosphere and prostate cancer cell cultures are marked by widespread intra-ecDNA and genome-wide chromosomal interactions. ecDNA-chromatin contact foci are characterized by broad and high-level H3K27ac signals converging predominantly on chromosomal genes of increased expression levels. Prostate cancer cells harboring synthetic ecDNA circles composed of characterized enhancers result in the genome-wide activation of chromosomal gene transcription. Deciphering the chromosomal targets of ecDNAs at single-molecule resolution reveals an association with actively expressed oncogenes spatially clustered within ecDNA-directed interaction networks. Our results suggest that ecDNA can function as mobile transcriptional enhancers to promote tumor progression and manifest a potential synthetic aneuploidy mechanism of transcription control in cancer.
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Project description:Extrachromosomal DNA (ecDNA) is prevalent in human cancers and mediates high oncogene expression through gene amplification and altered gene regulation. Gene induction typically involves cis regulatory elements that contact and activate genes on the same chromosome. Here we show that ecDNA hubs, clusters of ~10-100 ecDNAs within the nucleus, enable intermolecular enhancer-gene interactions to promote oncogene overexpression in trans. ecDNAs encoding multiple distinct oncogenes form hubs in diverse cancer cell types and primary tumors. Each ecDNA is more likely to transcribe the oncogene when spatially clustered with additional ecDNAs. ecDNA hubs are tethered by the BET protein BRD4 in a MYC-amplified colorectal cancer cell line. BET inhibitor JQ1 disperses ecDNA hubs and preferentially inhibits ecDNA-based oncogene transcription. A BRD4-bound promoter in PVT1 is ectopically fused to MYC and duplicated in ecDNA, receiving promiscuous enhancer input to drive potent MYC expression. PVT1 promoter on a heterologous episome suffices to mediate gene activation in trans by ecDNA hubs in a JQ1-sensitive manner. Systematic CRISPRi silencing of ecDNA enhancers reveal intermolecular enhancer-gene activation among multiple oncogene loci amplified on distinct ecDNAs. Together, these results demonstrate that ecDNA hubs are protein-tethered clusters of ecDNAs which enable intermolecular transcriptional regulation. ecDNA hubs may act as units of oncogene function, cooperative evolution, and potential targets for cancer therapy.
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Project description:Extrachromosomal DNA (ecDNA) is prevalent in human cancers and mediates high oncogene expression through gene amplification and altered gene regulation. Gene induction typically involves cis regulatory elements that contact and activate genes on the same chromosome. Here we show that ecDNA hubs, clusters of ~10-100 ecDNAs within the nucleus, enable intermolecular enhancer-gene interactions to promote oncogene overexpression in trans. ecDNAs encoding multiple distinct oncogenes form hubs in diverse cancer cell types and primary tumors. Each ecDNA is more likely to transcribe the oncogene when spatially clustered with additional ecDNAs. ecDNA hubs are tethered by the BET protein BRD4 in a MYC-amplified colorectal cancer cell line. BET inhibitor JQ1 disperses ecDNA hubs and preferentially inhibits ecDNA-based oncogene transcription. A BRD4-bound promoter in PVT1 is ectopically fused to MYC and duplicated in ecDNA, receiving promiscuous enhancer input to drive potent MYC expression. PVT1 promoter on a heterologous episome suffices to mediate gene activation in trans by ecDNA hubs in a JQ1-sensitive manner. Systematic CRISPRi silencing of ecDNA enhancers reveal intermolecular enhancer-gene activation among multiple oncogene loci amplified on distinct ecDNAs. Together, these results demonstrate that ecDNA hubs are protein-tethered clusters of ecDNAs which enable intermolecular transcriptional regulation. ecDNA hubs may act as units of oncogene function, cooperative evolution, and potential targets for cancer therapy.
2021-05-24 | GSE175452 | GEO
Project description:Extrachromosomal DNA (ecDNA) is prevalent in human cancers and mediates high oncogene expression through gene amplification and altered gene regulation. Gene induction typically involves cis regulatory elements that contact and activate genes on the same chromosome. Here we show that ecDNA hubs, clusters of ~10-100 ecDNAs within the nucleus, enable intermolecular enhancer-gene interactions to promote oncogene overexpression in trans. ecDNAs encoding multiple distinct oncogenes form hubs in diverse cancer cell types and primary tumors. Each ecDNA is more likely to transcribe the oncogene when spatially clustered with additional ecDNAs. ecDNA hubs are tethered by the BET protein BRD4 in a MYC-amplified colorectal cancer cell line. BET inhibitor JQ1 disperses ecDNA hubs and preferentially inhibits ecDNA-based oncogene transcription. A BRD4-bound promoter in PVT1 is ectopically fused to MYC and duplicated in ecDNA, receiving promiscuous enhancer input to drive potent MYC expression. PVT1 promoter on a heterologous episome suffices to mediate gene activation in trans by ecDNA hubs in a JQ1-sensitive manner. Systematic CRISPRi silencing of ecDNA enhancers reveal intermolecular enhancer-gene activation among multiple oncogene loci amplified on distinct ecDNAs. Together, these results demonstrate that ecDNA hubs are protein-tethered clusters of ecDNAs which enable intermolecular transcriptional regulation. ecDNA hubs may act as units of oncogene function, cooperative evolution, and potential targets for cancer therapy.
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