title: Role for amplification and expression of glypican-5 in rhabdomyosarcoma.
abstract: Overexpression of genes, through genomic amplification and other mechanisms, can critically affect the behavior of tumor cells. Genomic amplification of the 13q31-32 region is reported in many tumors, including rhabdomyosarcomas that are primarily pediatric sarcomas resembling developing skeletal muscle. The minimum overlapping region of amplification at 13q31-32 in rhabdomyosarcomas was defined as containing two genes: Glypican-5 (GPC5) encoding a cell surface proteoglycan and C13orf25 encompassing the miR-17-92 micro-RNA cluster. Genomic copy number and gene expression analyses of rhabdomyosarcomas indicated that GPC5 was the only gene consistently expressed and up-regulated in all cases with amplification. Constitutive overexpression and knockdown of GPC5 expression in rhabdomyosarcoma cell lines increased and decreased cell proliferation, respectively. A correlation between expression levels of nascent pre-rRNA and GPC5 (P = 0.001), but not a C13orf25 transcript containing miR-17-92, in primary samples supports an association of GPC5 with proliferative capacity in vivo. We show that GPC5 increases proliferation through potentiating the action of the growth factors fibroblast growth factor 2 (FGF2), hepatocyte growth factor (HGF), and Wnt1A. GPC5 enhanced the intracellular signaling of FGF2 and HGF and altered the cellular distribution of FGF2. The mesoderm-inducing effect of FGF2 and FGF4 in Xenopus blastocysts was also enhanced. Our data are consistent with a role of GPC5, in the context of sarcomagenesis, in enhancing FGF signaling that leads to mesodermal cell proliferation without induction of myogenic differentiation. Furthermore, the properties of GPC5 make it an attractive target for therapeutic intervention in rhabdomyosarcomas and other tumors that amplify and/or overexpress the gene.
authors.affiliation: Molecular Cytogenetics Team, Paediatric Oncology, Cancer Research UK Centre for Cancer Therapeutics, The Institute of Cancer Research, Sutton, Surrey, United Kingdom.
authors.forename: Daniel
authors.initials: D
authors.lastname: Williamson
authors.forename: Joanna
authors.initials: J
authors.lastname: Selfe
authors.forename: Tony
authors.initials: T
authors.lastname: Gordon
authors.forename: Yong-Jie
authors.initials: YJ
authors.lastname: Lu
authors.forename: Kathy
authors.initials: K
authors.lastname: Pritchard-Jones
authors.forename: Kasumi
authors.initials: K
authors.lastname: Murai
authors.forename: Phil
authors.initials: P
authors.lastname: Jones
authors.forename: Paul
authors.initials: P
authors.lastname: Workman
authors.forename: Janet
authors.initials: J
authors.lastname: Shipley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D048708:Cell Growth Processes / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism; D002882:Chromosomes, Human, Pair 13; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D051519:Fibroblast Growth Factor 4 / Q000378:metabolism; D005784:Gene Amplification; D018628:Gene Dosage; D015870:Gene Expression; D053673:Glypicans / Q000096:biosynthesis* / Q000235:genetics*; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D035683:MicroRNAs / Q000235:genetics; D008845:Microinjections; D008969:Molecular Sequence Data; D012313:RNA / Q000008:administration & dosage / Q000235:genetics; D012208:Rhabdomyosarcoma / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction; D014982:Xenopus laevis
chemical_list: C496445:FGF4 protein, human; D051519:Fibroblast Growth Factor 4; C106228:GPC5 protein, human; C120300:GPC6 protein, human; D053673:Glypicans; D035683:MicroRNAs; D016222:Fibroblast Growth Factor 2; D012313:RNA; D017228:Hepatocyte Growth Factor