Experimental Papers
Copyright ©The Author(s) 1996. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Mar 25, 1996; 2(1): 3-5
Published online Mar 25, 1996. doi: 10.3748/wjg.v2.i1.3
Oncoprotein expression and inhibition of apoptosis during colorectal tumorigenesis
Xiao-Qiang Zhuang, Shi-Zhen Yuan, Xiao-Huai Wang, Ri-Quan Lai, Zhu-Quan Luo
Xiao-Qiang Zhuang, Xiao-Huai Wang, Ri-Quan Lai, Zhu-Quan Luo, Department of Gastroenterology, general Hospital of Chinese PLA Guangzhou Commanding Area, Guangzhou 510010, Guangdong Province, China
Shi-Zhen Yuan, Department of Gastroenterology, Sun YatSen Memorial Hospital, Guangzhou 510120, Guangdong Province, China
Xiao-Qiang Zhuang, physician-in-charge, master of gastroenterology, having papers published.
Author contributions: All authors contributed equally to the work.
Correspondence to: Xiao-Qiang Zhuang, Physician-in-Charge, Master of Gastroenterology, Department of Gastroenterology, general Hospital of Chinese PLA Guangzhou Commanding area, Guangzhou 510010, Guangdong Province, China
Telephone: +86-20-6664097
Received: October 3, 1995
Revised: November 16, 1995
Accepted: December 21, 1995
Published online: March 25, 1996
Abstract

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.

Keywords: Colorectal neoplasms; Protein p53; Gene expression; Apoptosis; Bcl-2