Human Monoclonal Antibody Targeting the Heparan Sulfate Chains of Glypican-3 Inhibits HGF-Mediated Migration and Motility of Hepatocellular Carcinoma Cells

Heparan sulfate proteoglycans (HSPGs) participate in many processes related to tumor development, including tumorigenesis and metastasis. HSPGs contain one or more heparan sulfate (HS) chains that are covalently linked to a core protein. Glypican-3 (GPC3) is a cell surface-associated HSPG that is highly expressed in hepatocellular carcinoma (HCC). GPC3 is involved in Wnt3a-dependent HCC cell proliferation. Our previous study reported that HS20, a human monoclonal antibody targeting the HS chains on GPC3, inhibited Wnt3a/β-catenin activation. In the current study, we showed that the HS chains of GPC3 could mediate HCC cells' migration and motility. Knocking down GPC3 or targeting the HS chains by HS20 inhibited HCC cell migration and motility. However, HS20 had no effect on GPC3 knockdown cells or GPC3 negative cells. In addition, an antibody that recognizes the core protein of GPC3 did not change the rate of cell motility. HCC cell migration and motility did not respond to either canonical or non-canonical Wnt induction, but did increase under hepatocyte growth factor (HGF) treatment. HS20-treated HCC cells exhibited less ability for HGF-mediated migration and motility. Furthermore, HS20 inhibited in vitro HCC spheroid formation and liver tumor growth in mice. GPC3 interacted with HGF; however, a mutant GPC3 lacking the HS chain showed less interaction with HGF. Blocking the HS chains on GPC3 with HS20 reduced c-Met activation in HGF-treated HCC cells and 3D-cultured spheroids. Taken together, our study suggests that GPC3 is involved in HCC cell migration and motility through HS chain-mediated cooperation with the HGF/Met pathway, showing how HS targeting has potential therapeutic implications for liver cancer.