title: EWS-FLI1 employs an E2F switch to drive target gene expression.
abstract: Cell cycle progression is orchestrated by E2F factors. We previously reported that in ETS-driven cancers of the bone and prostate, activating E2F3 cooperates with ETS on target promoters. The mechanism of target co-regulation remained unknown. Using RNAi and time-resolved chromatin-immunoprecipitation in Ewing sarcoma we report replacement of E2F3/pRB by constitutively expressed repressive E2F4/p130 complexes on target genes upon EWS-FLI1 modulation. Using mathematical modeling we interrogated four alternative explanatory models for the observed EWS-FLI1/E2F3 cooperation based on longitudinal E2F target and regulating transcription factor expression analysis. Bayesian model selection revealed the formation of a synergistic complex between EWS-FLI1 and E2F3 as the by far most likely mechanism explaining the observed kinetics of E2F target induction. Consequently we propose that aberrant cell cycle activation in Ewing sarcoma is due to the de-repression of E2F targets as a consequence of transcriptional induction and physical recruitment of E2F3 by EWS-FLI1 replacing E2F4 on their target promoters.
authors.affiliation: Children's Cancer Research Institute, St. Anna Kinderkrebsforschung, Vienna 1090, Austria.
authors.forename: Raphaela
authors.identifier: http://orcid.org/0000-0001-6839-0322
authors.initials: R
authors.lastname: Schwentner
authors.affiliation: Department of Statistics, University of Warwick, Coventry, CV4 7AL, UK.
authors.forename: Theodore
authors.initials: T
authors.lastname: Papamarkou
authors.affiliation: Children's Cancer Research Institute, St. Anna Kinderkrebsforschung, Vienna 1090, Austria.
authors.forename: Maximilian O
authors.initials: MO
authors.lastname: Kauer
authors.affiliation: Department of Statistics, University of Warwick, Coventry, CV4 7AL, UK.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Stathopoulos
authors.affiliation: Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.affiliation: Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: Sven
authors.initials: S
authors.lastname: Bilke
authors.affiliation: Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Meltzer
authors.affiliation: Department of Statistics, University of Warwick, Coventry, CV4 7AL, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Girolami
authors.affiliation: Children's Cancer Research Institute, St. Anna Kinderkrebsforschung, Vienna 1090, Austria Dept. of Pediatrics, Medical University, Vienna 1090, Austria heinrich.kovar@ccri.at.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Kovar
mesh_terms: D000465:Algorithms; D001499:Bayes Theorem; D002453:Cell Cycle / Q000235:genetics; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D050699:E2F3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D050704:E2F4 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015151:Immunoblotting; D008957:Models, Genetic; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034802:RNA-Binding Protein EWS / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012512:Sarcoma, Ewing / Q000235:genetics / Q000378:metabolism / Q000473:pathology
chemical_list: D050699:E2F3 Transcription Factor; C098319:E2F3 protein, human; D050704:E2F4 Transcription Factor; C493762:E2F4 protein, human; C106031:EWS-FLI fusion protein; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS