RNAi profiling by array of human Ewings carcinoma cells to down regulate EWS-FLI1
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Gong-Hong Wei
PROVIDER: E-MEXP-2759 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Goal: identification of differentially expressed genes after STEAP1 silencing. Ewing tumors (ET) are characterized by oncogenic EWS/ETS translocations and early metastasis. STEAP1 is a membrane-bound channel protein of unkown function. While overexpressed in many cancers, STEAP1 expression is strongly restricted to mesenchymal stem cells, prostate and urothelium among benign tissues. Here we show that STEAP1 is a direct transcriptional target of EWS/FLI1 and critical for ET malignancy. We demonstrate that STEAP1 is most prominently expressed in ET among sarcomas and provide further evidence for the concept of STEAP1 as a universal diagnostic marker for carcinomas. Using RNA interference we determined that STEAP1 promotes cellular invasiveness and anchorage-independent growth in vitro and accelerates tumor growth and metastasis in vivo. Transcriptome and proteome analyses as well as functional studies reveal that STEAP1 contributes to the generation of reactive oxygen species that in turn regulate the levels of redox-sensitive signaling molecules and pro-metatstatic genes. In synopsis, these data illuminate the hitherto unkown oncogenic function of STEAP1 as a redox-modulator in ET and point to a potential role of STEAP1 as universal drug target for anti-cancer therapy. 6 samples (3x A673 cells; 3x SK-N-MC cells); for each cell line one sample was transfected with control non silencing siRNA and two samples with different STEAP1 siRNAs (siSTEAP1_2 and siSTEAP1_3).
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Project description:Using EWS-FLI and its parental transcription factor, FLI1, we created a unique experimental system to address questions regarding the genomic mechanisms by which chimeric transcription factors cause cancer. We found that in tumor cells, EWS-FLI targets regions of the genome distinct from FLI1, despite identical DNA-binding domains. In primary endothelial cells, however, EWS-FLI and FLI1 demonstrate similar targeting. To understand this mistargeting, we examined chromatin organization. Regions targeted by EWS-FLI are normally repressed and nucleosomal in primary endothelial cells. In tumor cells, however, bound regions are nucleosome-depleted and harbor the chromatin signature of enhancers. We next demonstrated that through chimerism, EWS-FLI acquired the ability to alter chromatin. Expression of EWS-FLI results in nucleosome depletion at targeted sites, whereas silencing of EWS-FLI in tumor cells restored nucleosome occupancy. Thus, the EWS-FLI chimera acquired chromatin-altering activity, leading to mistargeting, chromatin disruption, and ultimately transcriptional dysregulation. Examination of two transcription factors in two different cell types, as well as three histone methylation marks and FAIRE
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Project description:Ewing sarcoma (EwS) is characterized by EWSR1-ETS fusion transcription factors converting polymorphic GGAA microsatellites (mSats) into potent neo-enhancers. Although the paucity of additional mutations makes EwS a genuine model to study principles of cooperation between dominant fusion oncogenes and neo-enhancers, this is impeded by the limited number of well-characterized models. Here we present the Ewing Sarcoma Cell Line Atlas (ESCLA), comprising whole-genome, DNA methylation, transcriptome, proteome, and chromatin immunoprecipitation sequencing (ChIP-seq) data of 18 cell lines with inducible EWSR1-ETS knockdown. The ESCLA shows hundreds of EWSR1-ETS-targets, the nature of EWSR1-ETS-preferred GGAA mSats, and putative indirect modes of EWSR1-ETS-mediated gene regulation, converging in the duality of a specific but plastic EwS signature. We identify heterogeneously regulated EWSR1-ETS-targets as potential prognostic EwS biomarkers. Our freely available ESCLA (http://r2platform.com/escla/) is a rich resource for EwS research and highlights the power of comprehensive datasets to unravel principles of heterogeneous gene regulation by chimeric transcription factors.
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Project description:EWS-FLI1 is a chimeric ETS transcription factor that is, due to a chromosomal rearrangement, specifically expressed in Ewingâs sarcoma family tumors (ESFT) and is thought to be the initiating event in the development of the disease. Previous genomic profiling experiments have identified a number of EWS-FLI1 regulated genes and genes that discriminate ESFT from other sarcomas, but so far a comprehensive analysis of EWS-FLI1 dependent molecular functions characterizing this aggressive cancer is lacking. In this study a molecular function map of ESFT was constructed based on an integrative analysis of gene expression profiling experiments on a uniform microarray platform following EWS-FLI1 knockdown in a panel of five ESFT cell lines, and on gene expression data from the same platform of 59 primary ESFT tumors. Based on the assumption that EWS-FLI1 is the driving transcriptional force in ESFT pathogenesis, we predicted an inverse correlation of gene expression for EWS-FLI1 regulated genes between the putative tissue of origin and the cell lines under EWS-FLI1 knockdown conditions. Consistent with recent reports, mesenchymal progenitor cells (MPC) were found to fit this hypothesis best and were therefore used as the reference tissue for the construction of the molecular function map in ESFT. The interrelations of molecular pathways were visualized by measuring the similarity among annotated gene functions by gene sharing. The molecular function map highlighted distinct clusters of activities for EWS-FLI1 regulated genes in ESFT and revealed a striking difference between EWS-FLI1 up- and down-regulated genes: EWS-FLI1 induced genes mainly belong to cell cycle regulation, proliferation and response to DNA damage, while repressed genes were associated with differentiation and cell communication. This study revealed that EWS-FLI1 combines by distinct molecular mechanisms two important functions of cellular transformation in one protein, growth promotion and differentiation blockage. By taking MPC as a reference tissue a significant EWS-FLI1 signature was discovered in ESFT that only partially overlapped with previously published EWS-FLI1 dependent gene expression patterns, identifying a series of novel targets for the chimeric protein in ESFT. Our results may guide target selection for future ESFT specific therapies. Experiment Overall Design: EWS-FLI1 knock down was performed by expressing specific siRNAs against EWS-FLI1 as small hairpin (sh) RNAs from pSUPER-based retroviral expression constructs in 5 different Ewing's sarcoma cell lines (WE68, SK-N-MC, TC252, STA-ET-1, STA-ET-7.2). As a negative control in each cell line, pSTNeg (Ambion, Applied Biosystems, Brunn am Gebirge, Austria) encoding a scrambled shRNA with no significant similarity to human sequences was used.
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Project description:HeLa cell line was trasfected by a EWS siRNA oligo causing knock-down of EWS or a siRNA scrambled oligo Three biological replicates were labeled in direct and dye-swap microarray experiments and hybridized onto an Agilent custom splicing-sensitive microarray platform.
2011-09-19 | E-GEOD-22929 | biostudies-arrayexpress
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. *
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