Inactivation of PTEN is associated with increased angiogenesis and VEGF overexpression in gastric cancer

AIM: To investigate the expression of PTEN/MMAC(1)/TEP(1) and vascular endothelial growth factor (VEGF), their roles in biologic behavior and angiogenesis and their association in gastric cancer. METHODS: Immunohistochemical staining was used to evaluate the expression of PTEN, VEGF and microvascular density (MVD) on paraffin-embedded sections in 70 patients with primary gastric cancer and 24 patients with chronic superficial gastritis (CSG). Expression of PTEN, VEGF and MVD were compared with clinicopathological features of gastric cancer. The relationship between expression of PTEN, VEGF and MVD as well as the relationship between PTEN and VEGF expression in cancer cells were investigated. RESULTS: PTEN expression significantly decreased (t = 3.98, P<0.01) whereas both VEGF expression and MVD significant increased (t = 4.29 and 4.41, respectively, both P<0.01) in gastric cancer group compared with CSG group. PTEN expression was significantly down-regulated (t = 1.95,P<0.05) whereas VEGF expression (t = 2.37, P<0.05) and MVD (t = 3.28, P<0.01) was significantly up-regulated in advanced gastric cancer compared with early-stage gastric cancer. PTEN expression in gastric cancer showed a negative association with lymph node metastasis (t = 3.91, P<0.01), invasion depth (t = 1.95, P<0.05) and age (t = 4.69, P<0.01). MVD in PTEN-negative gastric cancer was significantly higher than that in PTEN-positive gastric cancer (t = 3.69, P<0.01), and there was a negative correlation between PTEN expression and MVD (gamma= -0.363, P<0.05). VEGF expression was positively associated with invasion depth (especially with serosa invasion, t = 4.69, P<0.01), lymph node metastasis (t = 2.31, P<0.05) and TNM stage (t = 3.04, P<0.01). MVD in VEGF-positive gastric cancer was significantly higher than that in VEGF-negative gastric cancer (t = 4.62, P<0.01), and there was a positive correlation between VEGF expression of and MVD (gamma= 0.512, P<0.05). VEGF expression in PTEN-negative gastric cancer was significantly stronger than that in PTEN-positive gastric cancer (t = 2.61, P<0.05), and there was a significantly negative correlation between the expression of VEGF and PTEN (gamma= -0.403, P<0.05). CONCLUSION: Our results imply that inactivation of PTEN gene and over-expression of VEGF contribute to the neovascularization and progression of gastric cancer. PTEN-related angiogenesis might be attributed to its up-regulation of VEGF expression. PTEN and VEGF could be used as the markers reflecting the biologic behaviors of tumor and viable targets in therapeutic approaches to inhibit angiogenesis of gastric cancers.