The effect of Vasohibin-1 expression and tumor-associated macrophages on the angiogenesis in vitro and in vivo.

Vasohibin-1 is an intrinsic inhibitor of angiogenesis induced by VEGF-A. However, there little is known about the relationship between Vasohibin-1 expression, angiogenesis, and tumor-associated macrophages (TAMs). Vasohibin-1 expression, VEGF-A expression, microvessel density (MVD) marked with CD34, and density of cells marked with CD68 were measured in 111 paraffin-embedded tissues of gastric cancer by immunohistochemistry. The length of tube forming structures of endothelial cells and mobility rate of gastric cancer cells in Matrigel were tested by three-dimensional live cell imaging system. The effect of TAMs on the tumor growth, MVD, and Vasohibin-1 expression was measured by nude mice tumor genesis assay in vivo. We found that high Vasohibin-1 protein expression correlated significantly with worse TNM stage (P = 0.002), metastatic lymph node (P = 0.014), distant metastasis (P = 0.022), overall survival (P < 0.001), and progression-free survival (P < 0.001) compared to those with low Vasohibin-1 expression. Vasohibin-1 protein expression had statistical correlation with the MVD (r = 0.860, P < 0.001), density of CD68(+) cells (r = 0.882, P < 0.001), and VEGF-A expression (r = 0.719, P < 0.001) in the gastric cancer tissues. Decreasing Vasohibin-1 expression with siRNA increased the length of tube forming structures of endothelial cells in co-culture with endothelial cells (EA-hy923), macrophages, and gastric cancers (Hs746T). Tumor volume (P = 0.001), Vasohibin-1 (P < 0.001), and VEGF-A (P < 0.001) expression in mice inoculated with AGS and THP (10:1) was significantly higher than that with AGS alone (P = 0.001). Vasohibin-1 protein expression had statistical correlation with VEGF expression (r = 0.786, P < 0.001) and MVD (r = 0.496, P = 0.014) in gastric xenografted tumor. Therefore, Vasohibin-1 might be a potential marker of worse prognosis and therapeutic target in gastric cancer. Vasohibin-1 might play an important role in the process of angiogenesis regulated by TAMs.