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. 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. 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: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 cellular origin of Ewing tumor (ET), a tumor of bone or soft tissues characterized by specific fusions between EWS and ETS genes, is highly debated. Through gene expression analysis comparing ETs with a variety of normal tissues, we show that the profiles of different EWS-FLI1-silenced Ewing cell lines converge toward that of mesenchymal stem cells (MSC). Moreover, upon EWS-FLI1 silencing, two different Ewing cell lines can differentiate along the adipogenic lineage when incubated in appropriate differentiation cocktails. In addition, Ewing cells can also differentiate along the osteogenic lineage upon long-term inhibition of EWS-FLI1. These in silico and experimental data strongly suggest that the inhibition of EWS-FLI1 may allow Ewing cells to recover the phenotype of their MSC progenitor. Experiment Overall Design: Ewing tumors and EWS-FLI-1 inhibited cell lines were profiled on Affymetrix U133A (GPL96) arrays.
Project description:We have performed a high-throughput RNA interference screen to identify targets inhibiting EWS-FLI1 driven cell proliferation in Ewing sarcoma cells. EWS-FLI1 expressing A673 Ewing sarcoma cells were screened both in presence and absence of EWS-FLI1 shRNA induction with druggable siRNA library. Leucine rich repeats and WD repeat Domain containing 1 (LRWD1) targeting siRNA pool was the strongest anti-proliferative hit identified only in presence of EWS-FLI1. Validation experiments confirmed the anti-proliferative effect of LRWD1 depletion especially in EWS-FLI1 expressing cells. Functional analysis of differentially expressed genes in LRWD1 depleted Ewing sarcoma cells showed over-representation of connective tissue development, cell projection morphogenesis and neuronal processes.