title: Loss of p16 pathways stabilizes EWS/FLI1 expression and complements EWS/FLI1 mediated transformation.
abstract: Ewings sarcoma and primitive neuroectodermal tumors (ES/PNET) are characterized by the fusion of the N-terminus of the EWS gene to the C-terminus of a member of the ETS family of transcription factors. While such fusion proteins are thought to play dominant oncogenic roles, it is unlikely that a single genetic alteration by itself will support cellular transformation. Given that EWS/FLI1 is only able to transform immortalized 3T3 fibroblasts and that 30% of ES/PNET tumors contain a homozygous deletion of the p16 locus, it is likely that other genetic events are required for EWS/FLI1 oncogenesis. Here we describe a complementary mechanism utilized in the establishment ES/PNET tumors. EWS/FLI1 has the capacity to induce apoptosis and growth arrest in normal MEFs. Such effects prevent the establishment of stable expression of the protein in these cells. When expressed in p16, p19(ARF), or p53 deficient MEFs, the apoptotic and growth arrest effects are attenuated, creating a environment permissive for stable expression of the protein. While loss of a single tumor suppressor is sufficient to establish expression of EWS/FLI1, cellular transformation requires further genetic perturbation.
authors.affiliation: Molecular Biology Institute, Gwynne Hazen Cherry Memorial Labs, University of California at Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: B
authors.initials: B
authors.lastname: Deneen
authors.forename: C T
authors.initials: CT
authors.lastname: Denny
mesh_terms: D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis; D015152:Blotting, Northern; D002455:Cell Division; D002471:Cell Transformation, Neoplastic; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D005347:Fibroblasts / Q000378:metabolism; D017353:Gene Deletion; D049452:Green Fluorescent Proteins; D006720:Homozygote; D015151:Immunoblotting; D007700:Kinetics; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D008954:Models, Biological; D009154:Mutation; D015514:Oncogene Proteins, Fusion / Q000096:biosynthesis* / Q000235:genetics*; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D012190:Retroviridae / Q000235:genetics; D013997:Time Factors; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics*; D014161:Transduction, Genetic; D025803:Tumor Suppressor Protein p14ARF / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: C417743:Cdkn2a protein, mouse; D019941:Cyclin-Dependent Kinase Inhibitor p16; C106031:EWS-FLI fusion protein; D008164:Luminescent Proteins; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; D049452:Green Fluorescent Proteins