Published online Mar 25, 1996. doi: 10.3748/wjg.v2.i1.3
Revised: November 16, 1995
Accepted: December 21, 1995
Published online: March 25, 1996
AIM: To study bcl-2 and p53 protein expression and inhibition of apoptosis during colorectal tumorigenesis.
METHODS: Expression of bcl-2 and p53 was detected by immunohistochemical staining of 45 colorectal adenomas, 61 colorectal carcinomas, and 15 pathologically-confirmed normal colorectal biopsies.
RESULTS: The bcl-2 and p53 protein expression was uniformly negative in the normal mucosa specimens, whereas bcl-2 and p53 positive rates were significantly higher in the adenoma and carcinoma specimens (P < 0.01). Strong bcl-2 expression was often present in areas of severe dysplasia. In the colorectal adenoma specimens, expression of p53 increased with increasing size and dysplasia, being higher in adenomas ≥ 20 mm in diameter than in adenomas < 10 mm in diameter (77.8% vs 35.0%, P < 0.05). p53 protein expression was correlated with differentiation and Duke's staging. A significant inverse correlation was found between immunostaining of bcl-2 and p53 in adenomas but not in carcinomas. Furthermore, carcinomas with a high percentage of bcl-2 positive cells were significantly more likely to have low rates of apoptosis.
CONCLUSION: Bcl-2 expression appears to be an early event in colorectal tumorigenesis that can inhibit apoptosis. p53 expression plays an important role in the development and malignant change of colorectal adenoma. Bcl-2 and p53 may represent useful markers of cell apoptosis.