Project description:LTβR signaling is crucial for immune development, homeostasis, and inflammation. To identify protein determinants that control the quality of LTβR function, we use a novel proteomics approach to identify EWS as a novel signaling component of this pathway. LTβR signaling protein, TRAF3, controls the protein binding activity of EWS via formation of mutually exclusive protein-protein interactions. With transcriptomics and knockdown experiments we identify several pro-inflammatory genes with induction kinetics that are controlled by EWS during LTβR signaling. Given the link between gene induction responsiveness and mRNA decay, we show EWS controls the decay of these transcripts.
Project description:Our objective is to clarify the function of EWS-POU5F1 chimera. Specifially, GBS6 cells were established from an undifferentiated bone sarcoma carrying translocation t(6;22)(p21;q12). The translocation resulted in a gene fusion between EWS and POU5F1. Gene expression analysis of t(6;22) undifferentiated sarcoma cell line GBS6 transfected with POU5F1 specific siRNA to investigate the function of EWS-POU5F1. Knockdown of EWS-POU5F1 using POU5F1 specific siRNAs. 3 control and 6 experimental replicates representing the same experiment repeated 3 times (1st, 2nd, 3rd).
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:The pathognomonic EWS/ETS fusion transcription factors drive Ewing sarcoma (EWS) by orchestrating an oncogenic transcription program. Therapeutic targeting of EWS/ETS has not been successful; therefore identifying mediators of the EWS/ETS function could offer new therapeutic targets. Here we describe the dependency of chromatin reader BET bromodomain proteins in EWS/ETS driven transcription and investigate the potential of BET inhibitors in treating this lethal cancer. Similar to EWS/ETS fusions, knockdown of BET proteins BRD2/3/4 severely impaired the oncogenic phenotype of EWS cells. Notably, EWS/FLI1 and EWS/ERG was found to be in a transcriptional complex consisting of BRD4. RNA-Seq analysis upon BRD4 knockdown or its pharmacologic inhibition by the BET inhibitor JQ1 revealed an attenuated EWS/ETS transcriptional signature. In contrast to other reports, JQ1 reduced proliferation, and induced apoptosis through MYC-independent mechanism without affecting EWS/ETS protein levels, which was further confirmed by depleting BET proteins using PROTAC-BET degrader (BETd). Interestingly, polycomb repressive complex 2 (PRC2) associated factor PHF19 was downregulated by JQ1/BETd or BRD4 knockdown in multiple EWS cells. ChIP-seq analysis revealed occupancy of EWS/FLI1 at a distal regulatory element of PHF19 and its subsequent knockdown resulted in downregulation of PHF19 expression. Furthermore, deletion of PHF19 by CRISPR-Cas9 system lead to a decreased tumorigenic phenotype and increased sensitivity to JQ1. Importantly, PHF19 expression was associated with worse prognosis of Ewing sarcoma patients. In vivo, JQ1 demonstrated anti-tumor efficacy in multiple mouse xenograft models of EWS. Together, these results indicate that EWS/ETS require BET epigenetic reader proteins for its transcriptional program including PHF19 expression, which can be mitigated by BET inhibitors. Moreover, this study provides a clear rationale for the clinical utility of BET inhibitors in treating Ewing sarcoma.
Project description:Our objective is to clarify the function of EWS-POU5F1 chimera. Specifially, GBS6 cells were established from an undifferentiated bone sarcoma carrying translocation t(6;22)(p21;q12). The translocation resulted in a gene fusion between EWS and POU5F1. Gene expression analysis of t(6;22) undifferentiated sarcoma cell line GBS6 transfected with POU5F1 specific siRNA to investigate the function of EWS-POU5F1.
Project description:Ewing’s sarcoma (EWS) is a cancer of the bones or soft tissues in children and adolescents. EWS-FLI1 is a transcriptional factor and the key driver of EWS. To characterize the changes of downstream transcriptional profiles of EWS-FLI1 in A673 cells upon knockdown of EWS-FLI1 and deubiquitinase USP9X, RNA-seq was performed in A673 cells transfected with EWS-FLI1 esiRNA, USP9X esiRNA or GFP esiRNA as control. The data indicates that USP9X regulates transcriptional profiles of EWS through mediating EWS-FLI1.
Project description:Although EWS/FLI-1 fusion protein is responsible for most EwingM-bM-^@M-^Ys sarcoma family tumors (ESFT), the function of native EWS remains largely unknown. Here, we first showed that EWS repressed protein expression in a tethering assay. mRNAs bound to EWS were determined by RNA-immunoprecipitation Chip assay, and one of them, proline-rich Akt substrate of 40 kDa (PRAS40) mRNA, directly interacted with EWS. The inhibitor of AKT, API-2, repressed ESFT cell proliferation. We demonstrate that EWS negatively regulated PRAS40 protein expression through binding to PRAS40 3M-bM-^@M-^YUTR. Furthermore, PRAS40 knockdown inhibited the proliferation and metastatic potential of ESFT cells. Cytoplasmic lysates or whole cell lysates were prepared from HeLa S3 cells transfected with pFLAG-EWS , and incubated with anti-FLAG M2 Affinity Gel (Sigma) at 4M-BM-0C for 2 h. RNAs from lysates and immunoprecipitates were analysed using GeneChip Human Genome U133 Plus 2.0 Array (Affymetrix).
Project description:Although EWS/FLI-1 fusion protein is responsible for most Ewing’s sarcoma family tumors (ESFT), the function of native EWS remains largely unknown. Here, we first showed that EWS repressed protein expression in a tethering assay. mRNAs bound to EWS were determined by RNA-immunoprecipitation Chip assay, and one of them, proline-rich Akt substrate of 40 kDa (PRAS40) mRNA, directly interacted with EWS. The inhibitor of AKT, API-2, repressed ESFT cell proliferation. We demonstrate that EWS negatively regulated PRAS40 protein expression through binding to PRAS40 3’UTR. Furthermore, PRAS40 knockdown inhibited the proliferation and metastatic potential of ESFT cells.
Project description:A chromosomal translocation fusion gene product EWS-WT1 is the defining genetic event in Desmoplastic Small Round Cell Tumor (DSRCT), a rare but aggressive tumor with a high rate of mortality. EWS-WT1 oncogene acts as an aberrant transcription factor that drives tumorigenesis, but the mechanism by which EWS-WT1 causes tumorigenesis is not well understood. To delineate the oncogenic mechanisms, we generated the EWS-WT1 fusion in the mouse using a gene targeting (knock-in) approach, enabling physiologic expression of EWS-WT1 under the native Ews promoter. We derived mouse embryonic fibroblasts (MEFs) and performed genome-wide expression profiling to identify transcripts directly regulated by EWS-WT1. Remarkably, expression of EWS-WT1 led to a dramatic induction of many neuronal genes. Notably, a neural reprogramming factor, ASCL1 (achaete-scute complex-like 1), was highly induced by EWS-WT1 in MEFs and in primary DSRCT. Further analysis demonstrated that EWS-WT1 directly binds to the proximal promoter region of ASCL1 and activates its transcription through multiple WT1-responsive elements. Depletion of EWS-WT1 in a DSRCT cell line resulted in severe reduction in ASCL1 expression and cell viability. Remarkably, when stimulated with neuronal induction media, cells expressing EWS-WT1 expressed neural markers and generated neurite-like projections. These results demonstrate for the first time that EWS-WT1 activates neural gene expression and is capable of directing partial neuronal differentiation, likely via ASCL1. These findings suggest that stimulating DSRCT tumor cells with biological or chemical agents that promote neural differentiation might be a useful approach to develop novel therapeutics against this incurable disease. mouse embryonic fibroblasts (MEFs) and performed genome-wide expression profiling to identify transcripts directly regulated by EWS-WT1 in 0 vs. 24 Hours in three replications (WT+KTS, or WT-KTS in 0, 24 H; CRE in 0 and 24H)