Project description:Posterior homeobox D genes, in particular HOXD13, are over-expressed by Ewing sarcoma, a tumor driven by the oncogenic fusion protein EWS-FLI1. Here, we have found that EWS-FLI1 maintains HOXD13 expression through a GGAA microsatellite enhancer in the developmental posterior HOXD regulatory domain. Activation of this enhancer is EWS-FLI1 dependent and epigenomic silencing of this region leads to loss of HOXD13 expression in Ewing sarcoma cells, but not in unrelated cells. To determine the function of HOXD13 activation in Ewing sarcoma we performed nascent RNA sequencing upon HOXD13 knockdown. We identified NT5E as a target induced by HOXD13. NT5E encodes for the cell surface marker CD73, so we used CITE-seq to profile these cells.
Project description:Posterior homeobox D genes, in particular HOXD13, are over-expressed by Ewing sarcoma, a tumor driven by the oncogenic fusion protein EWS-FLI1. Here, we have found that EWS-FLI1 maintains HOXD13 expression through a GGAA microsatellite enhancer in the developmental posterior HOXD regulatory domain. Activation of this enhancer is EWS-FLI1 dependent and epigenomic silencing of this region leads to loss of HOXD13 expression in Ewing sarcoma cells, but not in unrelated cells. To determine the function of HOXD13 activation in Ewing sarcoma we performed nascent RNA sequencing or RNA sequencing upon HOXD13 knockdown.
Project description:Posterior homeobox D genes, in particular HOXD13, are over-expressed by Ewing sarcoma, a tumor driven by the oncogenic fusion protein EWS-FLI1. Here, we have found that EWS-FLI1 maintains HOXD13 expression through a GGAA microsatellite enhancer in the developmental posterior HOXD regulatory domain. RNA-seq of shHOXD13 defined HOXD13-ergulated genes, so we performed CUT&RUN for HOXD13 and histone marks (H3K27ac, H3K4me3, H3K4me1, and H3K27me3) to determine how it regulates target genes.
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 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.
Project description:we report a synthetic lethality of ETV6 and EWS-FLI1 in ewing sarcome that is imposed by ETV6 antagonize EWS-FLI1 from particular GGAA microsatellite sites
Project description:The molecular hallmark of the Ewing family of tumors is the presence of balanced chromosomal translocations leading to the formation of chimerical transcription factors (i.e. EWS/FLI1) that play a pivotal role in the pathogenesis of Ewing tumors by deregulating gene expression. We have recently demonstrated that DAX1 (NR0B1), an orphan nuclear receptor which was not previously implicated in cancer, is induced by the EWS/FLI1 oncoprotein and is highly expressed in Ewing tumors, suggesting that DAX1 is a biologically relevant target of EWS/FLI1-mediated oncogenesis. In this work we demonstrate that DAX1 is a direct transcriptional target of the EWS/FLI1 oncoprotein through its binding to a GGA-rich region in the DAX1 promoter and show that DAX1 is a key player of EWS/FLI1-mediated oncogenesis. DAX1 silencing using an inducible model of RNA interference induces growth arrest in the A673 Ewing cell line and severely impairs its capability to grow in semisolid medium and form tumors in immunodeficient mice. Gene expression profile analysis demonstrated that about ten percent of the genes regulated by EWS/FLI1 in Ewing cells are DAX1 targets, confirming the importance of DAX1 in Ewing oncogenesis. These findings indicate that DAX1 is an important player in the pathogenesis of the Ewing family of tumors, identify new functions for DAX1 as a cell cycle progression regulator and open the possibility to new therapeutic approaches based on DAX1 function interference. A673 cells derived from Ewing sarcoma were genetically enginereed to express specific shRNAs against GFP (control), EWS/FLI1 and DAX1 upon doxycycline stimulation. Three independent clones and a polyclonal population from each enginereed cell were analyzed. Cells were stimulated with doxycycline for 72 hours to induce the expression of the corresponding shRNA and whole gene expression profile performed. Gene expression profile in A673 cells in which EWS/FLI1 or DAX1 were silenced were compared to the control cells.