EPCR promotes MGC803 human gastric cancer cell tumor angiogenesis in vitro through activating ERK1/2 and AKT in a PAR1-dependent manner

The endothelial cell protein C receptor (EPCR) serves a key role in activated protein C (APC)-mediated cytoprotective effects in endothelial cells, and is involved in the development of certain types of human cancer. To the best of our knowledge, the present study is the first to demonstrate that EPCR may exert effects on gastric cancer angiogenesis in vitro. To detect microvessel density (MVD), the microvascular endothelial cells were stained for cluster of differentiation (CD)31 and CD34 in 61 cases of surgical resection of gastric carcinoma tissues, and the association between the expression of EPCR protein and MVD was analyzed. In addition, to analyze the effect of EPCR expressed by gastric cancer cells on the proliferation, migration and angiogenic abilities of endothelial cells, human umbilical vein endothelial cells (HUVECs) were cultured with tumor-conditioned medium derived from EPCR knockdown or protease-activated receptor 1 (PAR1)-blocked MGC803 gastric cancer cells. A CCK-8 assay was used to assess the proliferation ability of the HUVECs. A Transwell assay was performed to assess the migration ability of the HUVECs and a Matrigel-based tube formation assay was used to assess the angiogenic activity of the HUVECs. The results demonstrated that the expression of EPCR was correlated with the MVD of gastric cancer tissues. When cultured with tumor-conditioned medium derived from EPCR knockdown or PAR1-blocked MGC803 cells, the proliferation, migration and tubules formation abilities of HUVECs were markedly inhibited markedly. The expression of phosphorylated (p)-extracellular signal regulated kinase 1/2, p-protein kinase B (AKT; s473) and p-AKT (T308) in the HUVECs was decreased. In addition, EPCR knockdown inhibited PAR1 activation in the MGC803 cells. These results indicated that the expression of EPCR in gastric cancer cell line MGC803 contributes to tumor angiogenesis in vitro by activating ERK1/2 and AKT, and that this effect of EPCR is dependent on PAR1 activation.