Project description:Human Ewing sarcoma cell line EW-8 with different levels of EWSR/FLI1 using siRNA-EWSR1 were collected and profiled using single-cell RNA-seq. The single-cell RNA-sequencing data identified diverse reponses leading to the prediction of two rare cell identities in an unperturbed population (si-Control) with stem-like and dormant-like characterisitics. These newly discovered cell states may play important roles in undrstanding cancer heterogeneity, drug resistance and recurrence in Ewing sarcoma .
Project description:Identification of druggable targets is a prerequisite for developing targeted therapies against Ewing sarcoma. We report the identification of Protein Kinase C Beta (PRKCB) as a protein specifically and highly expressed in Ewing sarcoma as compared to other pediatric cancers. Its transcriptional activation is directly regulated by the EWSR1-FLI1 oncogene. Getting insights in PRKCB activity we show that, together with PRKCA, it is responsible for the phosphorylation of histone H3T6, allowing global maintenance of H3K4 trimethylation on a variety of gene promoters. In the long term, PRKCB RNA interference induces apoptosis in vitro. More importantly, in xenograft mice models, complete impairment of tumor engraftment and even tumor regression were observed upon PRKCB inhibition, highlighting PRKCB as a most valuable therapeutic target. Deciphering PRKCB roles in Ewing sarcoma using expression profiling, we found a strong overlap with genes modulated by EWSR1-FLI1 and an involvement of RPKCB in regulating crucial signaling pathways. Altogether, we show that PRKCB may have two important independent functions and should be considered as highly valuable for understanding Ewing sarcoma biology and as a promising target for new therapeutic approaches in Ewing sarcoma. A673 Ewing cell line was treated for 72 hours by either control siRNA or siRNA directed against PRKCB or EWSR1-FLI1. Total RNAs were extracted and hybridized on HuGene1.1STv1 Affymetrix Arrays. Normalisation was performed using specific Brainarray Enrtez gene CDF file (v14.1).
Project description:To get insight in the functional role of EGR2 for Ewing sarcoma, we performed a transcriptional profiling of Ewing sarcoma cells after knockdown of EGR2 and compared the resulting transcriptional signature with that of EWSR1-FLI1-silenced Ewing sarcoma cells. In accordance with the strong EGR2-induction by EWSR1-FLI1, both genes highly significantly overlap in their transcriptional signatures. Gene-set enrichment analyses (GSEA) and DAVID (Database for Annotation, Visualisation and Integrated Discovery) gene ontology analyses indicated a strong impact of EGR2 on cholesterol and lipid biosynthesis resembling its function in orchestrating lipid metabolism of myelinating Schwann cells. A673 and SK-N-MC Ewing sarcoma cells were transfected with specific siRNAs directed against EGR2 or EWSR1-FLI1 or non-targeting control siRNA. 48 h thereafter RNA was harvested and processed for microarray analysis.
Project description:EWSR1-FLI1 is a chimeric transcription factor resulting from the pathognomonic translocation present in Ewing sarcoma cells. Here, we silenced EWSR1-FLI1 in different Ewing sarcoma cell lines. RNA from SKNMC, TC71 and MHH-ES1 cells was extracted 96h post transfection (siCT or siEWSR1-FLI1) or prior doxycycline (day 0) and 7 days after inducing silencing of EWSR1-FLI1 with doxycycline in ASP14 cells. RNA-seq was performed for all conditions.
Project description:Ewing sarcomas harbor few mutations beyond the chromosomal translocation that initiates disease and the mechanistic basis for the metastasis of these tumors remains poorly understood. The epigenome of Ewing sarcoma (EWS) cells reflects the regulatory state of genes associated with the DNA binding activity of the fusion oncoproteins EWSR1::FLI1 or EWSR1::ERG. In this study, we examined the repressive activities of the EWSR1::FLI1/ERG fusion oncoproteins. Focusing on one of the repressed EWSR1::FLI1/ERG target genes, ETS1, we detected EWSR1::FLI1 binding and a H3K27me3 repressive mark at this locus. Depletion of EWSR1::FLI1 results in ETS1’s binding of promoter regions, and we show ETS1 regulates the expression of multiple proteins that function in extracellular matrix organization including TENSIN3 (TSN3). Interestingly, TSN3 expression in EWS tumors significantly correlates with that of ETS1 (0.85, FDR <0.01). TNS3 is a focal adhesion protein that contributes to tumor cell migration by connecting the cytoplasmic tail of integrins to the actin cytoskeleton. EWS cell lines, in which we activated ETS1 expression (CRISPRa) exhibited increased TNS3 expression and a migratory phenotype. Critically, the activated ETS1 EWS cell lines show TNS3 accumulation at leading cell edges, with F-actin cytoskeletal reorganization, a phenotype associated with cell migration.
Project description:Ewing sarcomas harbor few mutations beyond the chromosomal translocation that initiates disease and the mechanistic basis for the metastasis of these tumors remains poorly understood. The epigenome of Ewing sarcoma (EWS) cells reflects the regulatory state of genes associated with the DNA binding activity of the fusion oncoproteins EWSR1::FLI1 or EWSR1::ERG. In this study, we examined the repressive activities of the EWSR1::FLI1/ERG fusion oncoproteins. Focusing on one of the repressed EWSR1::FLI1/ERG target genes, ETS1, we detected EWSR1::FLI1 binding and a H3K27me3 repressive mark at this locus. Depletion of EWSR1::FLI1 results in ETS1’s binding of promoter regions, and we show ETS1 regulates the expression of multiple proteins that function in extracellular matrix organization including TENSIN3 (TSN3). Interestingly, TSN3 expression in EWS tumors significantly correlates with that of ETS1 (0.85, FDR <0.01). TNS3 is a focal adhesion protein that contributes to tumor cell migration by connecting the cytoplasmic tail of integrins to the actin cytoskeleton. EWS cell lines, in which we activated ETS1 expression (CRISPRa) exhibited increased TNS3 expression and a migratory phenotype. Critically, the activated ETS1 EWS cell lines show TNS3 accumulation at leading cell edges, with F-actin cytoskeletal reorganization, a phenotype associated with cell migration.
Project description:Ewing sarcomas harbor few mutations beyond the chromosomal translocation that initiates disease and the mechanistic basis for the metastasis of these tumors remains poorly understood. The epigenome of Ewing sarcoma (EWS) cells reflects the regulatory state of genes associated with the DNA binding activity of the fusion oncoproteins EWSR1::FLI1 or EWSR1::ERG. In this study, we examined the repressive activities of the EWSR1::FLI1/ERG fusion oncoproteins. Focusing on one of the repressed EWSR1::FLI1/ERG target genes, ETS1, we detected EWSR1::FLI1 binding and a H3K27me3 repressive mark at this locus. Depletion of EWSR1::FLI1 results in ETS1’s binding of promoter regions, and we show ETS1 regulates the expression of multiple proteins that function in extracellular matrix organization including TENSIN3 (TSN3). Interestingly, TSN3 expression in EWS tumors significantly correlates with that of ETS1 (0.85, FDR <0.01). TNS3 is a focal adhesion protein that contributes to tumor cell migration by connecting the cytoplasmic tail of integrins to the actin cytoskeleton. EWS cell lines, in which we activated ETS1 expression (CRISPRa) exhibited increased TNS3 expression and a migratory phenotype. Critically, the activated ETS1 EWS cell lines show TNS3 accumulation at leading cell edges, with F-actin cytoskeletal reorganization, a phenotype associated with cell migration.
Project description:Ewing sarcomas harbor few mutations beyond the chromosomal translocation that initiates disease and the mechanistic basis for the metastasis of these tumors remains poorly understood. The epigenome of Ewing sarcoma (EWS) cells reflects the regulatory state of genes associated with the DNA binding activity of the fusion oncoproteins EWSR1::FLI1 or EWSR1::ERG. In this study, we examined the repressive activities of the EWSR1::FLI1/ERG fusion oncoproteins. Focusing on one of the repressed EWSR1::FLI1/ERG target genes, ETS1, we detected EWSR1::FLI1 binding and a H3K27me3 repressive mark at this locus. Depletion of EWSR1::FLI1 results in ETS1’s binding of promoter regions, and we show ETS1 regulates the expression of multiple proteins that function in extracellular matrix organization including TENSIN3 (TNS3). Interestingly, TNS3 expression in EWS tumors significantly correlates with that of ETS1 (0.85, FDR <0.01). TNS3 is a focal adhesion protein that contributes to tumor cell migration by connecting the cytoplasmic tail of integrins to the actin cytoskeleton. EWS cell lines, in which we activated ETS1 expression (CRISPRa) exhibited increased TNS3 expression and a migratory phenotype. Critically, the activated ETS1 EWS cell lines show TNS3 accumulation at leading cell edges, with F-actin cytoskeletal reorganization, a phenotype associated with cell migration.
Project description:Ewing sarcoma, a rare and aggressive pediatric cancer, is characterized by chromosomal translocations that give rise to chimeric transcription factors. The most frequent of these chromosomal translocations is the t(11;22) that produces the fusion of the EWSR1 and FLI1 genes to generate the chimeric transcription factor EWSR1::FLI1. EWSR1::FLI1 is the main oncogenic event in Ewing's sarcoma. Recently, it has been proposed that EWSR1::FLI1 levels may fluctuate in Ewing sarcoma cells, giving rise to two cell populations: cells expressing low levels of EWSR1::FLI1 are characterized by a more migratory and invasive phenotype, while cells expressing high levels of EWSR1::FLI1 are more proliferative. The identification and functional characterization of EWSR1::FLI1 gene targets is therefore relevant to understanding the pathobiology of Ewing sarcoma, which in turn could contribute to the identification of new therapeutic targets. Using this approach, we have observed that CD44, a transmembrane protein involved in cell adhesion and migration and associated with metastasis in various cancer types, is overexpressed in the EWSR1::FLI1-low phenotype. Our results suggest that CD44 may play a role in regulating cell migration in Ewing sarcoma cells and thus contribute to the spread of tumor cells.
Project description:EWSR1-FLI1 genome reprogramming through remodeling of enhancers is determinant for Ewing sarcoma (ES) tumorigenesis. We describe a non-canonical function of RING1B, a PRC1 subunit highly expressed in primary ES tumors, co-localizing genome wide with EWSR1-FLI1 in active enhancers. While retaining its repressive canonical activity, we find RING1B as necessary for the expression of key EWSR1-FLI1 activated targets like NKX2-2, SOX2 or IGF1 where it mainly exerts a role in promoting oncogene recruitment to enhancers. Knockdown of RING1B is sufficient to impair growth of tumor xenografts and expression of EWSR1-FLI1 induced neomorphic enhancers in vivo. Restoration of RING1B ubiquitin ligase activity by the AURKB inhibitor AZD1152 decreases expression of RING1B/EWSR1-FLI1 common targets. Overall, our findings demonstrate RING1B as a critical modulator of EWSR1-FLI1 induced chromatin remodeling.