title: Alteration of mesodermal cell differentiation by EWS/FLI-1, the oncogene implicated in Ewing's sarcoma.
abstract: The chimeric fusion gene EWS/FLI-1 is detected in most cases of Ewing's sarcoma (ES), the second most common malignant bone tumor of childhood. Although 80% of ES tumors develop in skeletal sites, the remainder can arise in almost any soft tissue location. The lineage of the cell developing the EWS/FLI-1 gene fusion has not been fully characterized but is generally considered to be of either mesenchymal or neural crest origin. To study this oncogene in a conceptually relevant target cell, EWS/FLI-1 was introduced into the murine cell line C2C12, a myoblast cell line capable of differentiation into muscle, bone, or fat. In this cellular context, EWS/FLI-1 profoundly inhibited the myogenic differentiation program. The block in C2C12 myogenic differentiation required the nuclear localization and DNA-binding functions of EWS/FLI-1 and was mediated by transcriptional and posttranscriptional suppression of the myogenic transcription factors MyoD and myogenin. Interestingly, C2C12-EWS/FLI-1 cells constitutively expressed alkaline phosphatase, a bone lineage marker, and were alkaline phosphatase positive by histochemistry but showed no other evidence of bone lineage commitment. Consistent with recent findings in human ES tumor cell lines, C2C12-EWS/FLI-1 cells constitutively expressed cyclin D1 and demonstrated decreased expression of the cell cycle regulator p21(cip1), even under differentiation conditions and at confluent density. This C2C12-EWS/FLI-1 cell model may assist in the identification of novel differentially expressed genes relevant to ES and provide further insight into the cell(s) of origin developing ES-associated genetic fusions.
authors.affiliation: Division of Hematology-Oncology, Department of Medicine, Simmons Cancer Center and Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8593, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Eliazer
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Spencer
authors.forename: Dan
authors.initials: D
authors.lastname: Ye
authors.forename: Eric
authors.initials: E
authors.lastname: Olson
authors.forename: Robert L
authors.initials: RL
authors.lastname: Ilaria
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002453:Cell Cycle; D002454:Cell Differentiation; D002460:Cell Line; D019070:Cell Lineage; D019938:Cyclin D1 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D005434:Flow Cytometry; D005822:Genetic Vectors; D007150:Immunohistochemistry; D051379:Mice; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D017570:MyoD Protein / Q000378:metabolism; D018008:Myogenin / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000378:metabolism / Q000502:physiology*; D009857:Oncogenes / Q000235:genetics; D010957:Plasmids / Q000378:metabolism; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D012190:Retroviridae / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012512:Sarcoma, Ewing / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; C106031:EWS-FLI fusion protein; D017570:MyoD Protein; C503801:Myog protein, mouse; D018008:Myogenin; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors; D019938:Cyclin D1; D000469:Alkaline Phosphatase