EGFL7 promotes hepatocellular carcinoma cell proliferation and inhibits cell apoptosis through increasing CKS2 expression by activating Wnt/beta-catenin signaling

Epidermal growth factor-like domain multiple 7 (EGFL7) is an important sport stimulating factor and motility related factors significantly enhanced the tumor cell metastasis and overexpressed in many cancers, including hepatocellular carcinoma (HCC), associated with tumorigenesis. However, the molecular mechanism by which EGFL7 regulates HCC cell proliferation and apoptosis and the correlation between EGFL7 and cyclin-dependent kinases regulatory subunit 2 (CKS2), which is essential for biological function, have not fully explained. In this study, EGFL7 and CKS2 expression in patients with HCC was measured by real-time polymerase chain reaction and immunohistochemistry. After HCC cells respectively transfected with pLKO.1-EGFL7-shRNA, pLVX-Puro-EGFL7 recombined vector or CKS2 small interfering RNA, cell counting kit-8 and flow cytometry was performed to examine the cell proliferation and apoptosis, respectively, and the expression of beta-catenin, CKS2, CDK2, and cleaved caspase-3 was measured by Western blot analysis. We found that EGFL7 and CKS2 were overexpressed in HCC tissues and a positive correlation was found between them. EGFL7 knockdown markedly inhibited proliferation and promoted apoptosis of HCC cells, along with decreased expression of CKS2 and CDK2, but increased cleaved caspase-3 expression, while EGFL7 overexpression showed an opposite effect. EGFL7 silencing in nude mice also showed decreased tumor growth and altered protein expression similar to its effect in HCC cells in vitro. Importantly, CKS2 silencing significantly inhibited EGFL7-induced HCC cell proliferation and protein expression, and Wnt/beta-catenin signaling pathway inhibitor IWR-1-endo significantly inhibited CKS2 expression in HCC cells. Taken together, EGFL7 promotes HCC cell proliferation and inhibits cell apoptosis through increasing CKS2 expression by activating Wnt/beta-catenin signaling.