title: Microsatellites as EWS/FLI response elements in Ewing's sarcoma.
abstract: The ETS gene family is frequently involved in chromosome translocations that cause human cancer, including prostate cancer, leukemia, and sarcoma. However, the mechanisms by which oncogenic ETS proteins, which are DNA-binding transcription factors, target genes necessary for tumorigenesis is not well understood. Ewing's sarcoma serves as a paradigm for the entire class of ETS-associated tumors because nearly all cases harbor recurrent chromosomal translocations involving ETS genes. The most common translocation in Ewing's sarcoma encodes the EWS/FLI oncogenic transcription factor. We used whole genome localization (ChIP-chip) to identify target genes that are directly bound by EWS/FLI. Analysis of the promoters of these genes demonstrated a significant over-representation of highly repetitive GGAA-containing elements (microsatellites). In a parallel approach, we found that EWS/FLI uses GGAA microsatellites to regulate the expression of some of its target genes including NR0B1, a gene required for Ewing's sarcoma oncogenesis. The microsatellite in the NR0B1 promoter bound EWS/FLI in vitro and in vivo and was both necessary and sufficient to confer EWS/FLI regulation to a reporter gene. Genome wide computational studies demonstrated that GGAA microsatellites were enriched close to EWS/FLI-up-regulated genes but not down-regulated genes. Mechanistic studies demonstrated that the ability of EWS/FLI to bind DNA and modulate gene expression through these repetitive elements depended on the number of consecutive GGAA motifs. These findings illustrate an unprecedented route to specificity for ETS proteins and use of microsatellites in tumorigenesis.
authors.affiliation: Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA.
authors.forename: Kunal
authors.initials: K
authors.lastname: Gangwal
authors.forename: Savita
authors.initials: S
authors.lastname: Sankar
authors.forename: Peter C
authors.initials: PC
authors.lastname: Hollenhorst
authors.forename: Michelle
authors.initials: M
authors.lastname: Kinsey
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Haroldsen
authors.forename: Atul A
authors.initials: AA
authors.lastname: Shah
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Boucher
authors.forename: W Scott
authors.initials: WS
authors.lastname: Watkins
authors.forename: Lynn B
authors.initials: LB
authors.lastname: Jorde
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Graves
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Lessnick
mesh_terms: D001483:Base Sequence; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D004273:DNA, Neoplasm / Q000235:genetics; D006801:Humans; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D020218:Response Elements; D012512:Sarcoma, Ewing / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014162:Transfection
chemical_list: D004273:DNA, Neoplasm; C106031:EWS-FLI fusion protein; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors