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EcDNA hubs drive cooperative intermolecular oncogene expression [scRNA and scATAC-Seq]

ABSTRACT: Extrachromsomal DNA (ecDNA) are prevalent in human cancers and are associated with high oncogene expression as well as altered chromatin. Here we show that multiple ecDNAs cluster in the nucleus during interphase to form ecDNA hubs, where oncogene transcription preferentially occurs. Single-cell multiomics, single-molecule sequencing, and 3D enhancer connectome reveal MYC ecDNAs are heterogenous in primary sequence and that ecDNA hubs support ectopic and intermolecular enhancer-promoter interactions. Bromodomain-containing protein 4 (BRD4) extensively occupies ecDNA regulatory elements, and inhibition by JQ1 disperses ecDNA hubs and preferentially reduces ecDNA oncogene transcription. Two amplified oncogenes can intermix in ecDNA hubs, engage in intermolecular enhancer-promoter interactions, and transcription is uniformly sensitive to JQ1. Thus, ecDNA hubs – nuclear bodies of many ecDNAs tethered by proteins – are platforms for cooperative oncogene transcription. The recognition of ecDNA hubs as units of oncogene function and diversification has potentially broad implications for cancer cell evolution and therapy.

ORGANISM(S): Homo sapiens

PROVIDER: GSE160148 | GEO | 2020/11/25

REPOSITORIES: GEO

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ecDNA hubs drive cooperative intermolecular oncogene expression [HiChIP]

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.

2020-11-25 | GSE159985 | GEO