Journal Article

ecDNA hubs drive cooperative intermolecular oncogene expression

Helmsauer, Konstantin, Wong, Ivy Tsz-Lo, Chen, Celine, Duffy, Connor V., Liu, Zhe, Granja, Jeffrey M., Mischel, Paul S., Belk, Julia A., Bagchi, Anindya, Henssen, Anton G., Weiser, Natasha E., Tang, Jun, Mundlos, Stefan, Xie, Liangqi, Rose, John C., Tjian, Robert, Luebeck, Jens, Yost, Kathryn E., Friedlein, Jordan, Bafna, Vineet, Shi, Quanming, Hung, King L., Satpathy, Ansuman T., Valieva, Maria E., Wu, Sihan, Li, Rui, Chang, Howard Y., Dehkordi, Siavash R., Corces, M. Ryan, Chamorro González, Rocío, Rajkumar, Utkrisht, Schöpflin, Robert, Lange, Joshua T., Kraft, Katerina

2021

Overview

Extrachromosomal DNA (ecDNA) is prevalent in human cancers and mediates high expression of oncogenes through gene amplification and altered gene regulation 1 . Gene induction typically involves cis -regulatory elements that contact and activate genes on the same chromosome 2 , 3 . Here we show that ecDNA hubs—clusters of around 10–100 ecDNAs within the nucleus—enable intermolecular enhancer–gene interactions to promote oncogene overexpression. ecDNAs that encode multiple distinct oncogenes form hubs in diverse cancer cell types and primary tumours. Each ecDNA is more likely to transcribe the oncogene when spatially clustered with additional ecDNAs. ecDNA hubs are tethered by the bromodomain and extraterminal domain (BET) protein BRD4 in a MYC -amplified colorectal cancer cell line. The BET inhibitor JQ1 disperses ecDNA hubs and preferentially inhibits ecDNA-derived-oncogene transcription. The BRD4-bound PVT1 promoter is ectopically fused to MYC and duplicated in ecDNA, receiving promiscuous enhancer input to drive potent expression of MYC . Furthermore, the PVT1 promoter on an exogenous episome suffices to mediate gene activation in trans by ecDNA hubs in a JQ1-sensitive manner. Systematic silencing of ecDNA enhancers by CRISPR interference reveals intermolecular enhancer–gene activation among multiple oncogene loci that are amplified on distinct ecDNAs. Thus, protein-tethered ecDNA hubs enable intermolecular transcriptional regulation and may serve as units of oncogene function and cooperative evolution and as potential targets for cancer therapy. Extrachromosomal DNA (ecDNA) congregates in clusters called ecDNA hubs that promote intermolecular interactions between gene-regulatory regions and thereby amplify the expression of oncogenes such as MYC in cancer cell lines.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 14 / 14/32 / 45 / 45/15 / 45/23 / 631/67/2329 / 631/67/395 / 631/67/68/2486 / Amplification / Azepines - pharmacology / Cancer / Cell Cycle Proteins - genetics / Cell division / Cell Line, Tumor / Chromosomes / Colorectal cancer / Colorectal carcinoma / CRISPR / DNA / Enhancers / Gene Amplification / Gene expression / Gene Expression Regulation, Neoplastic / Gene regulation / Genetic aspects / Genomes / Health aspects / Hubs / Humanities and Social Sciences / Humans / multidisciplinary / Myc protein / Neoplasms - genetics / Nuclear Proteins - genetics / Oncogenes / Oncogenes - genetics / Oncology, Experimental / Proteins / Regulatory sequences / RNA polymerase / Science / Science (multidisciplinary) / Transcription Factors - genetics / Tumors