Glypican-3 promotes cell proliferation and tumorigenesis through up-regulation of β-catenin expression in lung squamous cell carcinoma

As a cell surface proteoglycan anchored by glycosyl-phosphatidylinositol, Glypican-3 (GPC3) is reported to be highly expressed in hepatocellular carcinoma (HCC) and to promote cell proliferation and tumorigenesis through activating Wnt/β-catenin signalling. GPC3 is also overexpressed in lung squamous cell carcinoma (SCC), but its effects and mechanisms in the progression of lung SCC remain unknown. The present study aims to explore the role and molecular mechanism of GPC3 in the occurrence and development of lung SCC. Immunohistochemistry, Western blot (WB) and real-time PCR (RT-PCR) assays were used to determine the expression patterns of GPC3 in lung SCC tissues and cells. MTT, flow cytometry and in vivo xenotransplantation assays were used to evaluate the influence of GPC3 on the growth, apoptosis and tumorigenesis of lung SCC cells. The results showed that GPC3 expression levels in lung SCC tissues and cells were significantly elevated, and the high expression of GPC3 significantly promoted cell growth and tumorigenesis and repressed cell apoptosis, as well as increased β-catenin expression. Moreover, knockdown of β-catenin obviously weakened GPC3 role in the promotion of cell proliferation and tumorigenesis, as well as the inhibition of cell apoptosis. In conclusion, the present study demonstrates that up-regulation of GPC3 accelerates the progression of lung SCC in a β-catenin-dependent manner. Our study provides a theoretical basis for GPC3/β-catenin as a novel diagnostic marker and therapeutic target for lung SCC.