Effect of GPC1 on epithelial-to-mesenchymal transition and stemness and interaction with ITGB1 in gastric cancer.

Abstract

e15580 Background: Gastric cancer is the fourth frequently diagnosed cancer worldwide and tumor metastasis plays an important role in its poor prognosis. EMT, which occurs during embryonic development and carcinoma progression, contributes to metastasis and regulates stemness. GPC1, a member of the heparan sulfate proteoglycans family, is overexpressed in many types of cancer, and associates with metastasis and tumor progression. However, it is unknown that the functions of GPC1 and its underlying mechanism in gastric cancer. Methods: Immunohistochemistry analysis was performed in 245 GC tissues to explore the relationship between GPC1 and tumor metastasis. Transwell migration and wound-healing assay were conducted to evaluate the effects of GPC1 on migration and invasiveness. Epithelial marker and mesenchymal markers expression in GC cells were detected by Western blot and immunofluorescence. GPC1 expression induced by TGF-β was detected by Western Blot. After GPC1 was knock downed, the metastatic effect and EMT markers induced by TGF-β were detected. Co-Immunoprecipitation was used to detect the interaction between ITGB1 and GPC1. Results: The expression of GPC1 was higher in GC tissues than in adjacent normal tissues and associated with poor prognosis. Knocking down GPC1 suppressed EMT and stemness which reduced metastasis in vivo and vitro by inhibiting Erk1/2 MAPK and FAK/Akt pathways. TGF-β stimulation significantly upregulated the expression of GPC1 whereas knocking down of GPC1 reversed TGF-β-mediated EMT and stemness. Moreover, we found that knocking down GPC1 could downregulate ITGB1 which was known to promote EMT in gastric cancer. Overexpression of ITGB1 counteracted the influence of knocking down GPC1 on EMT and stemness. Furthermore, GPC1 formed a complex with ITGB1, which indicated that the ability of GPC1 to stimulate EMT is ITGB1-dependent. Conclusions: We conclude that GPC1, through its interaction with ITGB1, plays an important role in regulating TGF-β-mediated EMT and stemness, and could be a potential future therapeutic target to prevent progression of gastric cancer.