Mithramycin Alters EWS::FLI1 DNA Binding and RNA Polymerase II Processivity to Inhibit Nascent Transcription
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE305545 | GEO | 2026/01/19
REPOSITORIES: GEO
Similar Datasets
Project description:Although many DNA binding natural products exert their effects through non-specific mechanisms, a therapeutic opportunity exists for a subset of these compounds that alter the expression or activity of specific driver oncogenes in specific cell contexts. In this study, we integrate CUT&Tag with Global Run-On Sequencing (CUT, Tag, and GRO) to show that the minor groove binding compound, mithramycin (MMA), inhibits the Ewing sarcoma oncogenic driver, the EWS::FLI1 transcription factor. MMA causes either an increase or decrease in EWS::FLI1 binding to chromatin at downstream target response elements to poison nascent transcription. The reversal of EWS::FLI1 activity is limited by non-specific effects of the drug on RNAPII processivity but can be optimized by continuous administration at low concentration to cause more precise reversal of the oncogenic transcriptome and striking Ewing sarcoma xenograft regressions. The activity in vivo is further improved with a less-toxic second-generation analog, AIT-102.
2026-01-22 | GSE316978 | GEO
Project description:Although many DNA binding natural products exert their effects through non-specific mechanisms, a therapeutic opportunity exists for a subset of these compounds that alter the expression or activity of specific driver oncogenes in specific cell contexts. In this study, we integrate CUT&Tag with Global Run-On Sequencing (CUT, Tag, and GRO) to show that the minor groove binding compound, mithramycin (MMA), inhibits the Ewing sarcoma oncogenic driver, the EWS::FLI1 transcription factor. MMA causes either an increase or decrease in EWS::FLI1 binding to chromatin at downstream target response elements to poison nascent transcription. The reversal of EWS::FLI1 activity is limited by non-specific effects of the drug on RNAPII processivity but can be optimized by continuous administration at low concentration to cause more precise reversal of the oncogenic transcriptome and striking Ewing sarcoma xenograft regressions. The activity in vivo is further improved with a less-toxic second-generation analog, AIT-102.
2026-01-22 | GSE316977 | GEO
Project description:EWS-FLI1 is the driver oncogene in >85% of Ewing sarcoma tumors. We used siRNA to knock down EWS-FLI1 for 48h hours in two Ewing sarcoma cell lines (EW8, TC71) to identify downstream genes and pathways affected by loss of EWS-FLI1 activity. RNAseq analysis was performed after 48 hours of treatment with a nontargeting siControl or siEWS-FLI1.
2024-09-30 | GSE263504 | GEO
Project description:Ewing sarcoma (EwS) is an adolescent and young adult sarcoma characterized by chromosome translocations between members of the FET family of RNA binding proteins and members of the ETS family of transcription factors, the most frequent fusion being EWS-FLI1. EWS-FLI1 acts as a pioneer factor, creating de novo enhancers and activating genes located in the vicinity of EWS-FLI1-bound microsatellite sequences. recent results from our lab indicate that EWS-FLI1, which activates transcription through binding to the DNA at specific sites, can generate fully novel, unconventional transcription units in regions of the genome that are fully quiescent in normal cells (manuscript in preparation). The hypothesis of the project is that the open reading frames (ORFs) of these transcripts may encode peptides presented at the cell surface by HLA class I molecules and hence be recognized as non-self by the immune system. The aim of this study is to detect Ewing-specific neo-peptides/proteins using proteomics approach.
2022-05-12 | PXD027309 | Pride
Project description:Ewing sarcoma (EWS) is a malignant pediatric bone cancer. Most Ewing sarcomas are driven by EWS-FLI1 oncogenic transcription factor that plays roles in transcriptional regulation, DNA damage response, cell cycle checkpoint control, and alternative splicing. USP1, a deubiquitylase which regulates DNA damage and replication stress responses, is overexpressed at both the mRNA and protein levels in EWS cell lines compared to human mesenchymal stem cells, the EWS cell of origin. The functional significance of high USP1 expression in Ewing sarcoma is not known. Here, we identify USP1 as a transcriptional target of EWS-FLI1 and a key regulator of EWS cell survival. We show that EWS-FLI1 knockdown decreases USP1 mRNA and protein levels. ChIP and ChIP-seq analyses show EWS-FLI1 occupancy on the USP1 promoter. Importantly, USP1 knockdown or inhibition arrests EWS cell growth and induces cell death by apoptosis. We observe destabilization of Survivin (also known as BIRC5 or IAP4) and activation of caspases-3 and -7 following USP1 knockdown or inhibition in the absence of external DNA damage stimuli. Notably, EWS cells display hypersensitivity to combinatorial treatment of doxorubicin or etoposide, EWS standard of care drugs, and USP1 inhibitor compared to single agents alone. Together, our study demonstrates that USP1 is regulated by EWS-FLI1, the USP1-Survivin axis promotes EWS cell survival, and USP1 inhibition sensitizes EWS cells to standard of care chemotherapy.
2024-01-26 | PXD041033 | Pride
Project description:We show that EWS-FLI1, an aberrant transcription factor responsible for the pathogenesis of Ewing sarcoma, reprograms gene regulatory circuits by directly inducing or directly repressing enhancers. At GGAA repeats, which lack regulatory potential in other cell types and are not evolutionarily conserved, EWS- FLI1 multimers potently induce chromatin opening, recruit p300 and WDR5, and create de novo enhancers. GGAA repeat enhancers can loop to physically interact with target promoters, as demonstrated by chromosome conformation capture assays. Conversely, EWS-FLI1 inactivates conserved enhancers containing canonical ETS motifs by displacing wild-type ETS transcription factors and abrogating p300 recruitment. ChIP-seq for of 4 histone modifications (H3K27ac, H3K4me1, H3K4me3 and H3K27me3), FLI1, p300, WDR5, ELF1 and GABPA in primary Ewing sarcomas, Ewing sarcoma cell lines (A673 and SKMNC cells), and mesenchymal stem cells (MSC). EWS-FLI1 was knocked down in Ewing sarcoma cell lines with lentiviral shRNAs (shFLI1 and shGFP control). EWS-FLI1 was expressed in MSCs with lentiviral expression vectors (pLIV EWSFLI1 or pLIV empty vector control). * Raw data not provided for the MSC and Primary Ewing sarcoma samples. *
2014-10-30 | E-GEOD-61944 | biostudies-arrayexpress
Project description:Oncogenic transformation in Ewing sarcoma tumors is driven by the fusion oncogene EWS-FLI1. The inducible expression of EWS-FLI1 (EF) in embryoid bodies, or collections of differentiating stem cells, generates cells with properties of Ewing sarcoma tumors, including characteristics of transformation. These cell lines exhibit anchorage-independent growth, a lack of contact inhibition and a strong Ewing sarcoma gene expression signature. These cells also demonstrate a requirement for the persistent expression of EWS-FLI1 for cell survival and growth. We used microarrays to detail the effects of doxycycline-inducible expression of EWS-FLI1 on the gene expression signature of cells derived from differentiating stem cells, or embryoid bodies. Triplicate biological replicates were collected and analyzed.
2015-12-31 | E-GEOD-64686 | biostudies-arrayexpress
Project description:Ewing sarcoma is a highly aggressive tumor characterized by a translocation between members of the FET family of RNA binding proteins and one of several ETS transcription factors, with the most common translocation being EWS-FLI1. EWS-FLI1 leads to changes in gene expression through mechanisms that are not completely understood. We performed RNA sequencing analysis on primary pediatric human mesenchymal progenitor cells (pMPCs) expressing EWS-FLI1 in order to identify novel target genes. This analysis identified lnc277 as a previously uncharacterized long non-coding RNA upregulated by EWS-FLI1 in pMPCs. Inhibiting the expression of lnc277 diminished the ability of Ewing sarcoma cell lines to proliferate and form colonies in soft agar whereas inhibiting lnc277 had no effect on other cell types tested. By analyzing gene expression after shRNA knockdown, we found that both EWS-FLI1 and lnc277 repressed many more genes that they induced and that a significant fraction of EWS-FLI1 repressed targets were also repressed by lnc277. Analysis of primary human Ewing sarcoma RNA sequencing data further supports a role for lnc277 in mediating gene repression. We identified hnRNPK as an RNA binding protein that interacts directly with lnc277. We found a significant overlap in the genes repressed by hnRNPK and those repressed by both EWS-FLI1 and lnc277, suggesting that hnRNPK participates in lnc277 mediated gene repression. Thus, lnc277 is a previously uncharacterized long non-coding RNA downstream of EWS-FLI1 that facilitates the development of Ewing sarcoma via the repression of target genes. Our studies identify a novel mechanism of oncogenesis downstream of a chromosomal translocation and underscore the importance of lncRNA-mediated gene repression as a mechanism of EWS-FLI1 transcriptional regulation. A673 Ewing cells expressing an shRNA targeting hnRNPK or control were subjected to paired end RNA sequencing and compared to shGFP control.
2014-11-01 | E-GEOD-60890 | biostudies-arrayexpress
Project description:Ribonucleotide reductase (RNR) is the rate limiting enzyme in the synthesis of deoxyribonucleotides and the target of multiple chemotherapy drugs, including gemcitabine and hydroxyurea. In previous work, we identified that inhibition of RNR in Ewing sarcoma tumors upregulates the expression levels of multiple members of the activator protein-1 (AP-1) transcription factor family, including c-Jun and c-Fos, and downregulates the expression of c-Myc. However, the broader functions and downstream targets of AP-1, which are highly context- and cell-dependent, are unknown in Ewing sarcoma tumors. Consequently, in this work, we used genetically defined models, transcriptome profiling, and gene set enrichment analysis to identify that AP-1 and EWS-FLI1, the driver oncogene in most Ewing sarcoma tumors, reciprocally regulate the expression of multiple extracellular matrix proteins, including fibronectins, integrins, and collagens. AP-1 expression in Ewing sarcoma cells also drives, coincident with these perturbations in gene and protein expression, changes in cell morphology and phenotype. Furthermore, we also identified that the EWS-FLI1 oncoprotein dysregulates the expression of multiple AP-1 proteins, aligning with previous reports demonstrating genetic and physical interactions between EWS-FLI1 and AP-1. Overall, these results provide novel insight into the distinct, EWS-FLI1-dependent features of Ewing sarcoma tumors and identify a novel, reciprocal regulation of extracellular matrix components by EWS-FLI1 and AP-1.
2024-09-30 | GSE263503 | GEO
Project description:Ewing sarcoma is a highly aggressive tumor characterized by a translocation between members of the FET family of RNA binding proteins and one of several ETS transcription factors, with the most common translocation being EWS-FLI1. EWS-FLI1 leads to changes in gene expression through mechanisms that are not completely understood. We performed RNA sequencing analysis on primary pediatric human mesenchymal progenitor cells (pMPCs) expressing EWS-FLI1 in order to identify novel target genes. This analysis identified lnc277 as a previously uncharacterized long non-coding RNA upregulated by EWS-FLI1 in pMPCs. Inhibiting the expression of lnc277 diminished the ability of Ewing sarcoma cell lines to proliferate and form colonies in soft agar whereas inhibiting lnc277 had no effect on other cell types tested. By analyzing gene expression after shRNA knockdown, we found that both EWS-FLI1 and lnc277 repressed many more genes that they induced and that a significant fraction of EWS-FLI1 repressed targets were also repressed by lnc277. Analysis of primary human Ewing sarcoma RNA sequencing data further supports a role for lnc277 in mediating gene repression. We identified hnRNPK as an RNA binding protein that interacts directly with lnc277. We found a significant overlap in the genes repressed by hnRNPK and those repressed by both EWS-FLI1 and lnc277, suggesting that hnRNPK participates in lnc277 mediated gene repression. Thus, lnc277 is a previously uncharacterized long non-coding RNA downstream of EWS-FLI1 that facilitates the development of Ewing sarcoma via the repression of target genes. Our studies identify a novel mechanism of oncogenesis downstream of a chromosomal translocation and underscore the importance of lncRNA-mediated gene repression as a mechanism of EWS-FLI1 transcriptional regulation. RNA from primary human bone marrow derived mesenchymal cells either control or with inducible expression of EWS-FLI1 for 13 days was used to prepare PolyA selected cDNA libraries.
2014-11-01 | E-GEOD-60889 | biostudies-arrayexpress