title: Xg expression in Ewing's sarcoma is of prognostic value and contributes to tumor invasiveness.
abstract: Ewing's sarcoma (EWS) is an aggressive tumor of children and young adults that requires intensive treatment. The search for new prognostic factors is very important to choose the most appropriate therapy and to better understand the biology of the disease for the development of new therapeutic tools. We found that Xg, a thus far poorly described molecule and member of the CD99 family, is expressed in EWS cell lines and EWS primary tumors. Immunohistochemical analysis confirmed the expression of Xg in 24% of patients. We found that Xg expression in EWS defines a subgroup of patients with worse prognosis compared with those with Xg-negative localized tumors, indicating a clinical relevance of Xg expression in EWS. Forced expression of Xg in an EWS cell line upregulated cell migration and invasion in vitro. Furthermore, knockdown of Xg expression with specific short hairpin RNA significantly reduced migration and invasion of EWS cells. Consistent with these data, in vivo xenotransplant studies in nude mice revealed that Xg expression increased the incidence and the number of metastases of EWS cells. Thus, Xg expression is associated with lower overall survival in EWS patients with localized tumors and is implicated in metastasis.
authors.affiliation: Institut National de la Sante et de la Recherche Medicale UMR 576 and CHU Nice, Hopital de l'Archet, Laboratoire d'Immunologie, Nice, France.
authors.forename: Ophélie
authors.initials: O
authors.lastname: Meynet
authors.forename: Katia
authors.initials: K
authors.lastname: Scotlandi
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Pradelli
authors.forename: Maria C
authors.initials: MC
authors.lastname: Manara
authors.forename: Mario P
authors.initials: MP
authors.lastname: Colombo
authors.forename: Heidy
authors.initials: H
authors.lastname: Schmid-Antomarchi
authors.forename: Piero
authors.initials: P
authors.lastname: Picci
authors.forename: Alain
authors.initials: A
authors.lastname: Bernard
authors.forename: Ghislaine
authors.initials: G
authors.lastname: Bernard
mesh_terms: D000293:Adolescent; D000818:Animals; D001789:Blood Group Antigens / Q000096:biosynthesis*; D001859:Bone Neoplasms / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D002648:Child; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000276:immunology / Q000378:metabolism / Q000556:secondary; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D012516:Osteosarcoma / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D011379:Prognosis; D012512:Sarcoma, Ewing / Q000276:immunology / Q000378:metabolism* / Q000473:pathology
chemical_list: D001789:Blood Group Antigens; D015815:Cell Adhesion Molecules; C088785:XG protein, human