Expression Of BCL-2, BAG-1 Protein And Its Clinic Significance In Human Colorectal Carcinoma

BACKGROUND & OBJECTIVE: Cell apoptosis plays an important role in the development and progression of malignant tumour . Among apoptosis regulators , Bcl-2 inhibits apoptosis and cause tumours . Bag-1 is also an inhibitor of apoptosis . Bag-1 protein encoded by Bag-1 gene which called Bcl-2 associated athanogene-1 . It has no aminoacid homology with Bcl-2 protein . The protein functions are inhibiting apoptosis with binding to Bcl-2 and restraining cell apoptosis independently . This study was designed to investige the relationship of Bcl-2 & Bag-1 protein expressions in normal colorectal mucosa, adenoma and carcinoma tissues, and the development of colorectal carcinoma, and its clinical significance.METHODS: The expressions of Bag-1 and Bcl-2 protein in 20 normal colorectal mucosa, 35 colorectal adenoma and 82 colorectal carcinoma tissues were examined with S-P immunohistochemical staining.RESULTS: The positive rates of Bcl-2 protein in normal colorectal mucosa, adenoma and carcinoma tissues were 25%,80% and 65% respectively . The positive expression rates of Bcl-2 protein in colorectal adenoma and carcinoma tissues were significantly higher than that in normal colorectal mucosa tissues (P<0.05) , and the positive expression rate in colorectal adenoma tissues was higher than that in carcinoma tissues (P<0.05) . The expressions of Bcl-2 protein were not related to the age and sex of patients, differentiation degree, Duke's stage and lymph node metastasis (P>0.05) . The positive expression rates of Bag-1 protein in normal colorectal mucosa, colorectal adenoma and carcinoma tissues were10%, 60% and 81% respectively . The positive expression rates showed increasing trend from normal colorectal mucosa to adenoma to carcinoma , and the difference was statistic meaning (P<0.05) . No correlation was found between expression levels of Bag-1 protein and the age and sex of patients , butexpression levels of Bag-1 protein with differentiation degree, Duke' s stage and lymph node metastasis (PO.05), the expressions of nuclear Bag-1 and cytoplasm Bag-1 were not related to differentiation degree, Duke's stage and lymph node metastasis (F>0.05). Bcl-2 protein expression was positive correlation with Bag-1 protein expression in colorectal carcinoma (r=0.3827^P<0.05) .CONCLUSIONS: (1) In colorectal carcinoma , bcl-2 and Bag-1 genes are related to cell apoptosis. Compare to Bcl-2 , the apoptosis regulator activity of Bag-1 is more dominant . (2) Bcl-2 protein plays an important role in the occurance of colorectal carcinoma . The expression levels of Bcl-2 protein decrease from adenoma to carcinoma. (3) The overexpression of Bag-1 protein plays an important role in the development and progression of colorectal carcinoma . The expression levels of Bag-1 protein is related to the malignant degree of colorectal carcinoma and may be a new biomarker in predicting the potent invasion and the metastasis of colorectal carcinoma . (4) The occurance and progression of colorectal carcinoma are controlled by a variety of genes , and Bcl-2 and Bag-1 protein in the development of colorectal carcinoma enhance each other .