title: Soluble glypican 3 inhibits the growth of hepatocellular carcinoma in vitro and in vivo.
abstract: The heterogeneity of the molecular pathology of HCC poses a formidable obstacle to the development of non-cytotoxic therapies. Several pro-tumorigenic signaling pathways can be aberrantly activated in HCC, including those triggered by Wnts. Glypican-3 (GPC3), a membrane-bound heparan sulfate proteoglycan that is overexpressed in most HCCs, promotes the growth of these tumors by stimulating Wnt signaling. Because GPC3 binds with high affinity to Wnts, and its growth-promoting activity requires attachment to the cell membrane, we have hypothesized that a mutated GPC3 lacking the GPI anchoring domain (sGPC3) will block Wnt signaling and inhibit the growth of Wnt-dependent tumors. In addition, because sGPC3 displays heparan sulfate chains, this secreted glypican could also inhibit HCC growth by blocking the activity of other heparin-binding growth factors. To test this hypothesis, HCC cell lines were infected with an sGPC3-expressing lentivirus or virus control, and the effect of sGPC3 on the in vitro and in vivo growth was investigated. In addition, the signaling pathways targeted by sGPC3 were identified. We observed that sGPC3-expressing cells had lower proliferation rate. In addition, sGPC3 significantly inhibited the in vivo growth of the Huh6, HepG2 and Huh7 HCC cell lines. sGPC3 blocked Wnt signaling in Huh6- and Huh7-derived tumors and Erk1/2 and Akt phosphorylation in tumors generated by Huh7 and HepG2 cells, respectively. An anti-angiogenic effect in Huh7 and HepG2-derived tumors was also observed. We conclude that sGPC3 can inhibit HCC tumorigenicity by blocking the activity of several pro-tumorigenic growth factors.
authors.affiliation: Division of Molecular and Cellular Biology, Sunnybrook Research Institute and Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
authors.forename: Sandra I
authors.initials: SI
authors.lastname: Zittermann
authors.forename: Mariana I
authors.initials: MI
authors.lastname: Capurro
authors.forename: Wen
authors.initials: W
authors.lastname: Shi
authors.forename: Jorge
authors.initials: J
authors.lastname: Filmus
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D053673:Glypicans / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008114:Liver Neoplasms, Experimental / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D016513:Mice, SCID; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D014183:Transplantation, Heterologous; D047368:Tumor Burden; D051153:Wnt Proteins / Q000378:metabolism; D060508:Wnt3 Protein
chemical_list: D017261:Glycosylphosphatidylinositols; D053673:Glypicans; D051153:Wnt Proteins; D060508:Wnt3 Protein; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3