Project description:Extrachromosomal DNA (ecDNA) are circular DNA bodies that play critical roles in tumor progression and treatment resistance by amplifying oncogenes across a wide range of cancer types. ecDNA lack centromeres and are thus not constrained by typical Mendelian segregation, enabling their unequal accumulation within daughter cells and associated increases in copy number. Despite intrinsic links to their oncogenic potential, the fidelity and mechanisms of ecDNA inheritance are poorly understood. Here, we show that ecDNA are protected against cytosolic mis-segregation through mitotic clustering and by tethering to mitotic chromosome ends. High fidelity nuclear segregation of MYC-amplifying ecDNA depends on BRD4 transcriptional co-activation and mitotic transcription of the long non-coding RNA PVT1, which is co-amplified with MYC in colorectal and prostate cancer cell lines. Disruption of ecDNA mitotic clustering through BRD4 inhibition, PVT1 depletion, or inhibiting mitotic transcription results in cytosolic mis-segregation, ecDNA chromosomal reintegration, and the formation of homogeneously staining regions (HSRs). We propose that nuclear inheritance of ecDNA is facilitated by an RNA-based mechanism that clusters ecDNA during mitosis and protects against cytosolic missegregation and chromosomal reintegration.
Project description:Extrachromosomal DNA (ecDNA) amplification enhances intercellular oncogene dosage variability and accelerates tumor evolution by violating foundational principles of genetic inheritance through its asymmetric mitotic segregation. Spotlighting high-risk neuroblastoma we demonstrate how ecDNA amplification undermines the clinical efficacy of current therapies in cancers with extrachromosomal MYCN amplification. Integrating theoretical models of oncogene copy number-dependent fitness with single-cell ecDNA quantification and phenotype analyses, we reveal that ecDNA copy number heterogeneity drives phenotypic diversity and determines treatment sensitivity through mechanisms unattainable by chromosomal oncogene amplification. We demonstrate that ecDNA copy number directly influences critical cell fate decisions in cancer cell lines, patient-derived xenografts and primary neuroblastomas, illustrating how extrachromosomal oncogene dosage-driven phenotypic diversity offers a strong evolutionary advantage under therapeutic pressure. Furthermore, we identify senescent ecDNA-containing cells with reduced copy numbers in neuroblastomas and other MYC-amplified cancers as a source of treatment resistance and outline a strategy for their targeted elimination to improve the poor outcome of patients with MYCN-amplified cancers.
Project description:In this study, we established ecDNA-containing cell models by either transfecting synthetic circular DNA or excising endogenous chromosomal DNA. We found that ecDNA can be stable maintained in these cell models. By identifying proteins on nascent DNA, we found DNA damage repair pathway was significantly enriched in ecDNA-containing cells. ecDNA can activate DNA damage response. Further evidence show that TOP2B and LIG3. The association of ecDNA replication with cell proliferation and DNA damage response was explored by comprehensive profiling and analysis. Utilizing EdU (5-ethynyl-2’-deoxyuridine)-immunoprecipitation-mass spectrometry (EdU-IP-MS), we identified critical regulators involved in ecDNA replication and examined their functional roles in cancer cell DNA damage response and proliferation.
Project description:Chromothripsis, the shattering and imperfect reassembly of one (or a few) chromosome(s)1, is an ubiquitous2 mutational process generating localized and complex chromosomal rearrangements that drive genome evolution in cancer. Chromothripsis can be initiated by mis-segregation errors in mitosis3,4 or DNA metabolism5-7 that lead to entrapment of chromosomes within micronuclei and their subsequent fragmentation in the next interphase or following mitotic entry6,8-10. Here we use inducible degrons to demonstrate that chromothriptically produced pieces of a micronucleated chromosome are tethered together in mitosis by a protein complex consisting of mediator of DNA damage checkpoint 1 (MDC1), DNA topoisomerase II-binding protein 1 (TOPBP1) and cellular inhibitor of PP2A (CIP2A), thereby enabling en masse segregation to the same daughter cell. Such tethering is shown to be crucial for the viability of cells undergoing chromosome mis-segregation and shattering after transient inactivation of the spindle assembly checkpoint. Transient, degron-induced reduction in CIP2A following chromosome micronucleation-dependent chromosome shattering is shown to drive acquisition of segmental deletions and inversions. Analyses of pancancer tumour genomes showed that expression of CIP2A and TOPBP1 was increased overall in cancers with genomic rearrangements, including copy number-neutral chromothripsis with minimal deletions, but comparatively reduced in cancers with canonical chromothripsis in which deletions were frequent. Thus, chromatin-bound tethers maintain the proximity of fragments of a shattered chromosome enabling their re-encapsulation into, and religation within, a daughter cell nucleus to form heritable, chromothriptically rearranged chromosomes found in the majority of human cancers.
Project description:Extrachromosomal DNA (ecDNA) presents a major challenge for cancer patients. EcDNA renders tumours treatment-resistant by facilitating massive oncogene transcription and rapid genome evolution, contributing to poor patient survival. At present, there are no ecDNA-specific treatments. Here we show that enhancing transcription replication conflict enables targeted elimination of ecDNA-containing cancers. Stepwise analyses of ecDNA transcription reveal pervasive RNA transcription and associated single-stranded DNA (ssDNA), leading to excessive transcription replication conflicts and replication stress (RS) compared to chromosomal loci. Nucleotide incorporation on ecDNA is markedly slower, and RS is significantly higher in ecDNA-containing tumours regardless of cancer type or oncogene cargo. pRPA2-S33, a mediator of DNA damage repair that binds ssDNA, shows elevated localization on ecDNA in a transcription dependent manner, along with increased DNA double strand breaks, and activation of the S-phase checkpoint kinase, CHK1. Genetic or pharmacological CHK1 inhibition abrogates the DNA replication check point, causing extensive and preferential tumour cell death in ecDNA-containing tumours. We advance a highly selective, potent, and bioavailable oral CHK1 inhibitor, BBI-2779, that preferentially kills ecDNA-containing tumour cells. In a gastric cancer model containing FGFR2 on ecDNA, BBI-2779 suppresses tumour growth and prevents ecDNA-mediated acquired resistance to the pan-FGFR inhibitor infigratinib, resulting in potent and sustained tumour regression in mice. Transcription replication conflict emerges as a target for ecDNA-directed therapy, exploiting a synthetic lethality of excess to treat cancer. This SuperSeries is composed of the SubSeries listed below. This work was delivered as part of the eDyNAmiC team supported by the Cancer Grand Challenges partnership funded by Cancer Research UK (CGCATF-2021/100012 and CGCATF-2021/100025) and the National Cancer Institute (OT2CA278688 and OT2CA278635) to H.Y.C., P.S.M., and V.B. This project was supported by NIH RM1-HG007735 (H.Y.C., W.J.G., C.C.).
Project description:Extrachromosomal DNA (ecDNA) presents a major challenge for cancer patients. EcDNA renders tumours treatment-resistant by facilitating massive oncogene transcription and rapid genome evolution, contributing to poor patient survival. At present, there are no ecDNA-specific treatments. Here we show that enhancing transcription replication conflict enables targeted elimination of ecDNA-containing cancers. Stepwise analyses of ecDNA transcription reveal pervasive RNA transcription and associated single-stranded DNA (ssDNA), leading to excessive transcription replication conflicts and replication stress (RS) compared to chromosomal loci. Nucleotide incorporation on ecDNA is markedly slower, and RS is significantly higher in ecDNA-containing tumours regardless of cancer type or oncogene cargo. pRPA2-S33, a mediator of DNA damage repair that binds ssDNA, shows elevated localization on ecDNA in a transcription dependent manner, along with increased DNA double strand breaks, and activation of the S-phase checkpoint kinase, CHK1. Genetic or pharmacological CHK1 inhibition abrogates the DNA replication check point, causing extensive and preferential tumour cell death in ecDNA-containing tumours. We advance a highly selective, potent, and bioavailable oral CHK1 inhibitor, BBI-2779, that preferentially kills ecDNA-containing tumour cells. In a gastric cancer model containing FGFR2 on ecDNA, BBI-2779 suppresses tumour growth and prevents ecDNA-mediated acquired resistance to the pan-FGFR inhibitor infigratinib, resulting in potent and sustained tumour regression in mice. Transcription replication conflict emerges as a target for ecDNA-directed therapy, exploiting a synthetic lethality of excess to treat cancer. This work was delivered as part of the eDyNAmiC team supported by the Cancer Grand Challenges partnership funded by Cancer Research UK (CGCATF-2021/100012 and CGCATF-2021/100025) and the National Cancer Institute (OT2CA278688 and OT2CA278635) to H.Y.C., P.S.M., and V.B. This project was supported by NIH RM1-HG007735 (H.Y.C., W.J.G., C.C.).
Project description:Extrachromosomal DNA (ecDNA) presents a major challenge for cancer patients. EcDNA renders tumours treatment-resistant by facilitating massive oncogene transcription and rapid genome evolution, contributing to poor patient survival. At present, there are no ecDNA-specific treatments. Here we show that enhancing transcription replication conflict enables targeted elimination of ecDNA-containing cancers. Stepwise analyses of ecDNA transcription reveal pervasive RNA transcription and associated single-stranded DNA (ssDNA), leading to excessive transcription replication conflicts and replication stress (RS) compared to chromosomal loci. Nucleotide incorporation on ecDNA is markedly slower, and RS is significantly higher in ecDNA-containing tumours regardless of cancer type or oncogene cargo. pRPA2-S33, a mediator of DNA damage repair that binds ssDNA, shows elevated localization on ecDNA in a transcription dependent manner, along with increased DNA double strand breaks, and activation of the S-phase checkpoint kinase, CHK1. Genetic or pharmacological CHK1 inhibition abrogates the DNA replication check point, causing extensive and preferential tumour cell death in ecDNA-containing tumours. We advance a highly selective, potent, and bioavailable oral CHK1 inhibitor, BBI-2779, that preferentially kills ecDNA-containing tumour cells. In a gastric cancer model containing FGFR2 on ecDNA, BBI-2779 suppresses tumour growth and prevents ecDNA-mediated acquired resistance to the pan-FGFR inhibitor infigratinib, resulting in potent and sustained tumour regression in mice. Transcription replication conflict emerges as a target for ecDNA-directed therapy, exploiting a synthetic lethality of excess to treat cancer. This work was delivered as part of the eDyNAmiC team supported by the Cancer Grand Challenges partnership funded by Cancer Research UK (CGCATF-2021/100012 and CGCATF-2021/100025) and the National Cancer Institute (OT2CA278688 and OT2CA278635) to H.Y.C., P.S.M., and V.B. This project was supported by NIH RM1-HG007735 (H.Y.C., W.J.G., C.C.).
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.
Project description:Extrachromosomal DNA (ecDNA) presents a major challenge for cancer patients. EcDNA renders tumours treatment-resistant by facilitating massive oncogene transcription and rapid genome evolution, contributing to poor patient survival. At present, there are no ecDNA-specific treatments. Here we show that enhancing transcription replication conflict enables targeted elimination of ecDNA-containing cancers. Stepwise analyses of ecDNA transcription reveal pervasive RNA transcription and associated single-stranded DNA (ssDNA), leading to excessive transcription replication conflicts and replication stress (RS) compared to chromosomal loci. Nucleotide incorporation on ecDNA is markedly slower, and RS is significantly higher in ecDNA-containing tumours regardless of cancer type or oncogene cargo. pRPA2-S33, a mediator of DNA damage repair that binds ssDNA, shows elevated localization on ecDNA in a transcription dependent manner, along with increased DNA double strand breaks, and activation of the S-phase checkpoint kinase, CHK1. Genetic or pharmacological CHK1 inhibition abrogates the DNA replication check point, causing extensive and preferential tumour cell death in ecDNA-containing tumours. We advance a highly selective, potent, and bioavailable oral CHK1 inhibitor, BBI-2779, that preferentially kills ecDNA-containing tumour cells. In a gastric cancer model containing FGFR2 on ecDNA, BBI-2779 suppresses tumour growth and prevents ecDNA-mediated acquired resistance to the pan-FGFR inhibitor infigratinib, resulting in potent and sustained tumour regression in mice. Transcription replication conflict emerges as a target for ecDNA-directed therapy, exploiting a synthetic lethality of excess to treat cancer. This work was delivered as part of the eDyNAmiC team supported by the Cancer Grand Challenges partnership funded by Cancer Research UK (CGCATF-2021/100012 and CGCATF-2021/100025) and the National Cancer Institute (OT2CA278688 and OT2CA278635) to H.Y.C., P.S.M., and V.B. This project was supported by NIH RM1-HG007735 (H.Y.C., W.J.G., C.C.).
Project description:Extrachromosomal DNA (ecDNA) presents a major challenge for cancer patients. EcDNA renders tumours treatment-resistant by facilitating massive oncogene transcription and rapid genome evolution, contributing to poor patient survival. At present, there are no ecDNA-specific treatments. Here we show that enhancing transcription replication conflict enables targeted elimination of ecDNA-containing cancers. Stepwise analyses of ecDNA transcription reveal pervasive RNA transcription and associated single-stranded DNA (ssDNA), leading to excessive transcription replication conflicts and replication stress (RS) compared to chromosomal loci. Nucleotide incorporation on ecDNA is markedly slower, and RS is significantly higher in ecDNA-containing tumours regardless of cancer type or oncogene cargo. pRPA2-S33, a mediator of DNA damage repair that binds ssDNA, shows elevated localization on ecDNA in a transcription dependent manner, along with increased DNA double strand breaks, and activation of the S-phase checkpoint kinase, CHK1. Genetic or pharmacological CHK1 inhibition abrogates the DNA replication check point, causing extensive and preferential tumour cell death in ecDNA-containing tumours. We advance a highly selective, potent, and bioavailable oral CHK1 inhibitor, BBI-2779, that preferentially kills ecDNA-containing tumour cells. In a gastric cancer model containing FGFR2 on ecDNA, BBI-2779 suppresses tumour growth and prevents ecDNA-mediated acquired resistance to the pan-FGFR inhibitor infigratinib, resulting in potent and sustained tumour regression in mice. Transcription replication conflict emerges as a target for ecDNA-directed therapy, exploiting a synthetic lethality of excess to treat cancer. This work was delivered as part of the eDyNAmiC team supported by the Cancer Grand Challenges partnership funded by Cancer Research UK (CGCATF-2021/100012 and CGCATF-2021/100025) and the National Cancer Institute (OT2CA278688 and OT2CA278635) to H.Y.C., P.S.M., and V.B. This project was supported by NIH RM1-HG007735 (H.Y.C., W.J.G., C.C.).