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 growthpromoting 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.
Basic fibroblast growth factor (bFGF, FGF-2) is a potent angiogenic factor and endothelial cell mitogen. Although bFGF levels are increased in chronically inflamed tissue, its role in inflammation is unclear. We investigated the effect of bFGF on acute dermal inflammation and the recruitment of monocytes, T cells, and neutrophils. Leukocyte recruitment to inflamed sites was quantified with radiolabeled leukocytes. Intradermal injection of bFGF in rats did not induce leukocyte recruitment or inflammation. However, the recruitment of leukocytes to inflammation induced by tumor necrosis factor-alpha, interferon-gamma, C5a, or a delayed hypersensitivity reaction was enhanced by bFGF by 55 to 132% (P < 0.05). Either acute or prolonged bFGF treatment of dermal sites had this effect. The potentiating effect of bFGF on leukocyte recruitment was also seen in joints. There was no associated modulation of vascular permeability, blood flow, or angiogenesis in the sites by bFGF. However, the expression of the endothelial cell adhesion molecules (CAMs) for leukocytes, P-selectin, E-selectin, and ICAM-1, was significantly up-regulated in the inflamed tissue by bFGF, as quantified by radiolabeled anti-CAM antibody binding in vivo. Thus, although not directly proinflammatory, bFGF synergistically potentiates inflammatory mediator-induced leukocyte recruitment, at least in part, by enhancing CAM up-regulation on endothelium.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.