Study On The Correlation Between Protein Expression Of PTEN And VEGF In Colorectal Carcinoma

Colorectal cancer is one of the tumors with a relatively high incidence and mortality in the digestive system. Although many advanced measures have been taken to improve the outcome of patients suffering from colorectal cancer, up to now, there has been no radical progress in reducing its incidence and mortality. This could be due to the fact that the underlying mechanism in tumorigenesis and progression of colorectal cancer is still poorly understood. Many studies have demonstrated that tumor suppressor genes, such as p16 and p27, play an important role in oncogenesis and progression of various malignancies. Recently, many investigators have been interested in the role of PTEN, a novel tumor suppressor gene, located on chromosome band 10q 23. 3. Accumulated evidence has suggested that inactivation of PTEN gene was implicated in the carcinogenesis and progression of various tumors. Loss of PTEN expression was dominantly attributed to the inactive alteration of PTEN gene,including mutations, deletions, loss of heterozygosity (LOH) and promoter methylation in various malignancies, meaning that the expressive intensity of PTEN could almost embody the status of PTEN gene. VEGF, one of the most powerful pro-angiogenic factors, is dominantly involved in all the process including vascular endothelial cell mitosis, proliferation, adhesion and migration. The purpose of this study was to investigate the role of PTEN in tumorigenesis and progression of colorectal cancer and its association with VEGF expression.Materials and MethodsColorectal carcinoma tissues were obtained from 80 patients who received surgery in Jinhua Municipal Central Hospital during 2000-2003. Serial section of colorectal carcinomas were adopted for concomitant expressions of PTEN and VEGF by streptavidin-peroxidase(SP) immunohistochemical staining while the expression in normal colorectal mucosa were adopted as controls.ResultsThe immunohistochemical staining of PTEN and VEGF in serial sections of human colorectal carcinoma tissues have produced expected positive signals with clear background. The negative control shows no signal. Both PTEN and VEGF positive staining are located in cell plasma. The total positive rates of PTEN and VEGF protein staining in 80 cases of colorectal adenocarcinoma were 46.3% (37/80) and 77.5% (62/80) respectively. They were not significantly correlated with patients' age or histological type (P>0.05) . The low level of PTEN protein expression and the high levelof VEGF protein expression were positively correlated with the Dukes stage, serosa infiltration, lymph node metastasis of colorectal adenocarcinoma (P<0.01) . The expression of PTEN protein was negatively correlated with that of VEGF protein (P<0.01) .Conclusions1, There is a deletion or lower expression of tumor suppressor gene PTEN protein and it is correlated with the Dukes stage, serosa infiltration, lymph node metastasis in colorectal cancer.2, The high level expression of VEGF protein is associated with the Dukes stage, serosa infiltration, lymph node metastasis in colorectal carcinoma.3, The expression of PTEN protein was negatively correlated with that of VEGF protein.