Dataset Information

Structure-function based molecular relationships in Ewing's sarcoma.

ABSTRACT: Ewing's Sarcoma Oncogene (ews) on chromosome 22q12 is encoding a ubiquitously expressed RNA-binding protein (EWS) with unknown function that is target of tumor-specific chromosomal translocations in Ewing's sarcoma family of tumors. A model of transcription complex was proposed in which the heterodimer Rpb4/7 binds to EAD, connecting it to Core RNA Pol II. The DNA-binding domain, provided by EFP, is bound to the promoter. Rpb4/7 binds RNA, stabilizing the transcription complex. The complex Rpb4/7 can stabilize the preinitiation complexes by converting the conformation of RNA Pol II. EWS may change its conformation, so that NTD becomes accessible. Two different mechanisms of interaction between EWS and RNA Pol II are proposed: (I) an intermolecular EWS-EWS interaction between two molecules, pushing conformation from "closed" to "open" state, or (II) an intramolecular interaction inside the molecule of EWS, pushing conformation of the molecule from "closed" to "open" state. The modified forms of EWS may interact with Pol II subunits hsRpb5 and hsRpb7. The EWS and EFPs binding partners are described schematically in a model, an attempt to link the transcription with the splicing. The proposed model helps to understand the functional molecular interactions in cancer, to find new partners and ways to treat cancer.

SUBMITTER: Todorova R

PROVIDER: S-EPMC4320925 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Structure-function based molecular relationships in Ewing's sarcoma.

Todorova Roumiana R

BioMed research international 20150122

Ewing's Sarcoma Oncogene (ews) on chromosome 22q12 is encoding a ubiquitously expressed RNA-binding protein (EWS) with unknown function that is target of tumor-specific chromosomal translocations in Ewing's sarcoma family of tumors. A model of transcription complex was proposed in which the heterodimer Rpb4/7 binds to EAD, connecting it to Core RNA Pol II. The DNA-binding domain, provided by EFP, is bound to the promoter. Rpb4/7 binds RNA, stabilizing the transcription complex. The complex Rpb4/ ...[more]

PMID: 25688366

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Project description:BackgroundEWS-FLI1 is a chimeric ETS transcription factor that is, due to a chromosomal rearrangement, specifically expressed in Ewing's sarcoma family tumors (ESFT) and is thought to initiate the development of the disease. Previous genomic profiling experiments have identified 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.Methodology/principal findingsIn this study, a molecular function map of ESFT was constructed based on an integrative analysis of gene expression profiling experiments 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. Out of 80 normal tissues tested, mesenchymal progenitor cells (MPC) were found to fit the hypothesis that EWS-FLI1 is the driving transcriptional force in ESFT best and were therefore used as the reference tissue for the construction of the molecular function map. 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.Conclusions/significanceThis 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.

Project description:Ewing's sarcoma is a high-grade malignancy bone and soft tissue tumor that most commonly occurs in children and adolescents. Although the overall prognosis of Ewing's sarcoma has improved, the 5-year survival rate has not improved significantly. The study aimed to determine the risk factors independently associated with the prognosis of Ewing's sarcoma and to construct a nomogram to predict patient survival. Patients diagnosed with Ewing's sarcoma were collected from the Surveillance, Epidemiology, and End Results program database between 2004 and 2015 and further divided into training and validation cohort. Univariate and multivariate Cox regression analyses were used to identify meaningful independent prognostic factors. The nomogram was used to predict 3- and 5-year overall survival (OS) and cancer-specific survival (CSS). Finally, the nomogram was verified internally and externally through the training and validation cohorts, and the predictive capability was evaluated using the receiver operating characteristic (ROC) curve, C-index, and calibration curve and compared with that of the 7th TNM stage. A total of 1120 patients were divided into training (n = 713) and validation (n = 407) cohorts. Based on the multivariate analysis of the training cohort, a nomogram that integrated age, tumor size, primary site, N stage, and M stage was constructed (P < 0.05). The predicted C-indexes of OS and CSS of the training cohort were 0.744 (95% CI 0.717-0.771) and 0.743 (95% CI 0.715-0.770), respectively. However, the TNM stage had a C-index of 0.695 (95% CI 0.666-0.724) and 0.698 (95% CI 0.669-0.727) for predicting OS and CSS, respectively. The nomogram showed higher C-indexes than those in the TNM stage. Furthermore, the internal and external calibration curves showed good consistency between the predicted and observed values. Age, tumor size, primary site, N stage, and M stage are independent risk factors affecting the OS and CSS in Ewing's sarcoma patients. Compared with the 7th TNM staging, the nomogram consisting of these factors was more accurate for risk assessment and survival prediction in patients with Ewing's sarcoma, thus providing a novel reliable tool for risk assessment and survival prediction in Ewing's sarcoma patients.

Dataset Information

Structure-function based molecular relationships in Ewing's sarcoma.

Publications

Structure-function based molecular relationships in Ewing's sarcoma.

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