title: PTPL1 is a direct transcriptional target of EWS-FLI1 and modulates Ewing's Sarcoma tumorigenesis.
abstract: Ewing's Sarcoma family tumors (ESFT) are characterized by a translocation t(11:22) forming an aberrant transcription factor EWS-FLI1. Protein tyrosine phosphatase L1 (PTPL1) was identified as a gene upregulated by EWS-FLI1 in transfected cells by microarray. Our results show that PTPL1 is a transcriptional target of EWS-FLI1 both by chromatin immunoprecipitation and promoter activation studies. We demonstrate that PTPL1 is highly expressed in ESFT cells and patient tumors compared with normal tissues, with a trend towards higher expression in metastatic versus primary tumors. Reduction of PTPL1 protein in ESFT cells correlated with a significant reduction in both monolayer and soft-agar cell growth. In addition, these PTPL1-reduced cells were more sensitive to etoposide-induced apoptosis than the controls. We therefore report a novel transcriptional activation of a phosphatase involved in the oncogenesis of ESFT. Increasing interest in specific phosphatase inhibitors would allow PTPL1 to be evaluated as a therapeutic target in ESFT.
authors.affiliation: Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA.
authors.forename: Ogan D
authors.initials: OD
authors.lastname: Abaan
authors.forename: Amy
authors.initials: A
authors.lastname: Levenson
authors.forename: Osman
authors.initials: O
authors.lastname: Khan
authors.forename: Priscilla A
authors.initials: PA
authors.lastname: Furth
authors.forename: Aykut
authors.initials: A
authors.lastname: Uren
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Toretsky
mesh_terms: D000818:Animals; D001859:Bone Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D003001:Cloning, Molecular; D006801:Humans; D051379:Mice; D016297:Mutagenesis, Site-Directed; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D011485:Protein Binding; D054595:Protein Tyrosine Phosphatase, Non-Receptor Type 13; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D012512:Sarcoma, Ewing / Q000235:genetics* / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: C106031:EWS-FLI fusion protein; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors; C516742:PTPN13 protein, human; D054595:Protein Tyrosine Phosphatase, Non-Receptor Type 13; D017027:Protein Tyrosine Phosphatases; C516743:Ptpn13 protein, mouse