Immunohistochemical Expression of p53 Protein and CREB-binding Protein in Polyps and Adenocarcinomas of Colon

ABSTRACT

Purpose: Alterations in the structure of the p53 protein are one of the most common changes associated with human cancers. The CREB-binding protein(CBP) is a transcriptional co-activators of various sequence-specific DNA-binding transcription factors and is involved in a wide variety of cellular activities, such as DNA repair, cell growth, differentiation, and apoptosis. This article examined the expression levels of the p53 protein and CBP as well as their diagnostic value in a biopsy sample. METHODS: Immunohistochemical analysis were performed in 60 hyperplastic polyps, 180 adenomatous polyps, and 120 adenocarcinomas which had sampled from colono-fibroscopic exam from January 2000 to August 2003. RESULTS: 1. p53 protein expression was observed in 15% (9/60) of hyperplastic polyps, in 68.9% (124/180) of adenomatous polyps, and in 80% (96/120) of adenocarcinomas (P<0.01). 2. p53 protein expression according to the cellular atypia in the adenomatous polyp was observed in 45% (27/ 60) of mild dysplasia, 78.3% (47/60) of moderate dysplasia, and 83.4% (50/60) of severe dysplasia. There was an increasing tendency in high grade dysplasia, which is statistically significant (P<0.05). 3. p53 protein expression according to the level of differentiation was observed in 90% (54/60) of well differentiated adenocarcinomas, 78% (39/50) of moderately differentiated adenocarcinomas, and 30% (3/ 10) of poorly differentiated adenocarcinomas (P<0.01). 4. CBP expression was observed in 30% (18/60) of hyperplastic polyps, 70.6% (127/180), of adenomatous polyps, and 85% (102/120) of adenocarcinomas (P<0.01). 5. CBP expression according to cellular atypia in adenomatous polyp was observed in 48.3% (29/60) of mild dysplasia, 76.6% (46/60) of moderate dysplasia, and 86.7% (52/60) of severe dysplasia (P<0.05). 6. CBP expression according to cellular differentiation was observed in 90% (36/60) of well differentiated adenocarcinomas, 86% (43/50) of moderately differentiated adenocarcinomas, and 50% (5/10) of poorly differentiated adenocarcinomas (P<0.05). Conclusion: The p53 protein and CBP expression can indicate the malignant potentiality of the colon cell indirectly.