Project description:Response of HEK293-cells after transfection with EWS-FLI1. HEK293 cells were transfected with the expression vector pIRES2-EGFP containing type I EWS-FLI1 or empty control vector. For transient transfection standard DEAE dextran method was used and RNA was isolated 48h post transfection. For stable transfection cells were transfected using FuGENE 6 (Roche, Mannheim, Germany) and cells were selected with 400 ug/mL G418. DNA-microarray analysis was performed using Affymetrix HG-U133A microarrays.(see Staege et al. Cancer Res. 2004) Keywords = HEK293 Keywords = EWS-FLI1 Keywords = Ewing family tumors Keywords: other
Project description:Response of HEK293-cells after transfection with EWS-FLI1. HEK293 cells were transfected with the expression vector pIRES2-EGFP containing type I EWS-FLI1 or empty control vector. For transient transfection standard DEAE dextran method was used and RNA was isolated 48h post transfection. For stable transfection cells were transfected using FuGENE 6 (Roche, Mannheim, Germany) and cells were selected with 400 ug/mL G418. DNA-microarray analysis was performed using Affymetrix HG-U133A microarrays.(see Staege et al. Cancer Res. 2004)
Project description:Transient transfection of a Ewing's Sarcoma cell line expressing type I EWS-FLI1 fusion and doxycycline-inducible short hairpin RNA against EWS-FLI1 (A673sh)
Project description:Transient transfection of a Ewing's Sarcoma cell line expressing type I EWS-FLI1 fusion and doxycycline-inducible short hairpin RNA against EWS-FLI1 (A673sh) In total, 7 samples were analysed: empty vector control and two nuclear directed AKT- and CDK2- phosphorylation resistant FOXO1 versions as well as sh-scrambled and sh-FOXO1, either in the presence (w.o. Doxy.) or absence of EWS-FLI1 (+ Doxy.) each 2 replicates
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.
Project description:EWS-FLI1, a multi-functional fusion oncogene, is exclusively detectable in Ewing sarcomas. However, previous studies reported that a subset of osteosarcomas also harbor EWS-ETS family fusion, suggesting that the fusion gene may be involved in the development of a particular type of osteosarcomas. Here using the doxycycline inducible EWS-FLI1 system, we established an EWS-FLI1-dependent osteosarcoma model from murine bone marrow stromal cells. We revealed that the withdrawal of EWS-FLI1 expression enhances the osteogenic differentiation of sarcoma cells, leading to mature bone formation. Taking advantage of induced pluripotent stem cell (iPSC) technology, we also showed that the sarcoma-derived iPSCs with cancer-related genetic abnormalities exhibited the impaired differentiation program of osteogenic lineage irrespective of the EWS-FLI1 expression. Finally, we demonstrated that EWS-FLI1 contributed to in vitro sarcoma development from the sarcoma-iPSCs after osteogenic differentiation. These findings demonstrated that modulating cellular differentiation is fundamental principle of the EWS-FLI1-induced osteosarcoma development. Furthermore, the in vitro cancer model using sarcoma-iPSCs should provide a novel platform for dissecting relationship between cancer genome and cellular differentiation. Chip-seq in mouse EWS-FLI1-induced osteosarcoma cell lines (SCOS#2 )
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.
Project description:Ewing Sarcoma (EwS) is a EWS-FLI1- fusion driven pediatric bone cancer with high metastatic potential. Cellular plasticity, typically regulated via the Rho-pathway, is a prerequisite for metastasis initiation. Here we interrogated the role of the Rho transcriptional effectors MRTFA/B in EwS. We find MRTFB transcriptional function strongly repressed by EWS-FLI1. Under EWS-FLI1-low (knock-down) conditions, MRTFB is activated and antagonizes global EWS-FLI1-dependent transcription. Furthermore, ChIP-Seq revealed strong overlaps in MRTFB and EWS-FLI1 chromatin occupation, especially for EWS-FLI1 suppressed-(anticorrelated) genes. Enrichment of TEAD binding motifs in these shared genomic binding regions, and overlapping transcriptional footprints of MRTFB and TEAD1-4 perturbation led us to propose synergy between MRTFB and TEAD in the regulation of EWS-FLI1 suppressed-anticorrelated genes. Finally, we find F-actin assembly to be already perturbed in our EwS model, F-actin polymerization is perturbed by EWS-FLI1 in our model cell line, however,but pharmacological inhibition of actin polymerization still reduced expression serum-induced expression of MRTFB/YAP-1/TEAD target genes. In summary our data support a model of indirect and direct EWS-FLI1-driven perturbation of MRTFB/YAP-1/TEAD target gene regulation .
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. *
Project description:The fusion oncoprotein EWS-FLI1 arises from a t(11;22)(q24;q12) chromosomal translocation and causes Ewing's Sarcoma, a malignant bone tumor. The mechanism whereby EWS-FLI1 transforms cells is unknown. We made germline transgenic zebrafish expressing human EWS-FLI1 under the control of the heat shock promoter. Induction of EWS-FLI1 expression causes multiple defects in embryonic development. We compared gene expression in control and transgenic EWS-FLI1 zebrafish. The results identify a conserved set of EWS-FLI1-regulated genes, and provide insight into the pathogenesis of Ewing's Sarcoma tumors. We performed heat shock and isolated total RNA for microarray studies comparing wildtype AB strain zebrafish with transgenic zebrafish expressing human EWS-FLI1 [Tg(HSP:EWS-FLI1)]. RNA was biotin-lableled and hybridized to zebrafish-specific Affymetrix arrays.