PTEN/MMAC1/TEP1 mutations in human primary renal-cell carcinomas and renal carcinoma cell lines

Down-regulated expression of PTEN in colorectal cancer and its clinical significance

AIM: To study the expression of PTEN in colorectal carcinoma and its correlation with the clinicopathological features.

METHODS: Immunohistochemical SP technique was used to determine the expression of PTEN protein in 65 cases of colorectal carcinoma and their corresponding adjacent tissues, 13 cases of adenoma tissues, and 20 cases of normal colorectal tissues.

RESULTS: The expression of PTEN protein was mainly located in the nucleus and cytoplasm. The expression of PTEN protein was significantly lower in human colorectal cancer tissues than that in the corresponding adjacent tissues ones (56.92% vs 86.15%, P < 0.01), and it was also markedly lower in the lowly- and non-differentiated adenoma than that in the highly-and moderately-differentiated one (37.50% vs 75.76%, P < 0.01). The expression of PTEN protein in Dukes A and B stages were significantly higher than that in in Dukes C and D stages (73.33% vs 42.86%, P < 0.05). In addition, PTEN expression was correlated with lymph node metastasis (c² = 7.448, P < 0.01), but not with the sex, tumor sizes of patients.

CONCLUSION: The expression of PTEN is down-regulated in colorectal carcinoma, and it may be one of the molecular and biological indicators in reflecting the progression and prognosis of colorectal cancer.

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

AIM: To investigate the expression of PTEN/MMAC₁/TEP₁ 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 caner 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 (γ = -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 (γ = 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 (γ = -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.

Growth, invasion, metastasis, differentiation, angiogenesis and apoptosis of gastric cancer regulated by expression of PTEN encoding products

AIM: To investigate expression of PTEN in gastric cancer and to explore its roles in tumorigenesis and progression of gastric cancer.

METHODS: Formalin-fixed and paraffin-embedded tissues of adjacent non-tumor mucosa and primary foci from 113 cases of gastric cancers were studied for the expression of PTEN and Caspase-3 and microvessel density (MVD) by streptavidin-peroxidase (S-P) immunohistochemistry with antibodies against PTEN, Caspase-3, and CD34. The relationship between PTEN and Caspase 3 expression and clinicopathological parameters of tumors was compared.

RESULTS: Primary gastric cancer cells expressed PTEN less frequently than adjacent epithelial cells of primary foci (54.9% vs 89.4%; P = 0.000, χ² = 33.474). PTEN expression was significantly associated with invasive depth (P = 0.003, rs = 0.274), metastasis (P = 0.036, rs = 0.197), growth pattern (P=0.008, rs = 0.282), Lauren’s classification (P = 0.000, rs = 0.345), and histological classification (P = 0.005, rs = 0.262) of tumors, but not with tumor size (P = 0.639, rs = 0.045), Borrmann’s classification (P = 0.544, rs = 0.070) or TNM staging (P = 0.172, rs = 0.129). PTEN expression was negatively correlated with MDV in primary gastric cancer (P = 0.020, F = 5.558). Primary gastric cancer cells showed less frequent immunoreactivity to Caspase-3 than adjacent epithelial cells of primary foci (32.7% vs 50.4%; P = 0.007, χ² = 7.286). Caspase-3 expression was dependent of PTEN expression in primary gastric cancer cells (P = 0.000, χ² = 15.266).

CONCLUSION: Down-regulated expression of PTEN plays an important role in tumorigenesis, progression, growth, differentiation and angiogenesis of gastric cancer. Low expression of PTEN can decrease expression of Caspase-3 to disorder apoptosis of tumor cells, which might explain the molecular mechanisms of PTEN contributions to tumorigenesis and progression of gastric cancer.