Expression of Bcl-2 and p53 in the colorectal adenoma-carcinoma sequence.
To evaluate the respective roles of Bcl-2 and p53 during colorectal tumour growth, 73 sporadic adenomas and 54 carcinomas arising in adenomas were studied by immunohistochemistry. Bcl-2 protein was expressed in 72 of 73 (98.6%) adenomas and in 25 of 54 (46.3%) carcinomas, whereas p53 protein expression was found in 18 of 73 (24.6%) adenomas and 23 of 54 (42.6%) carcinomas. Bcl-2 expression was related to the size and increasing severity of dysplasia (p < 0.05), while p53 expression was associated with the degree of dysplasia, but not with size (p < 0.025 and p > 0.10, respectively). Bcl-2 expression in carcinomas arising in adenomas was significantly reduced when compared with the associated adenoma (p < 0.005). However, there was no such difference in p53 expression between carcinomas and associated adenomas. Interestingly, there were inverse correlations between p53 and Bcl-2 expression in both adenomas and carcinomas (p < 0.05 and p < 0.005, respectively). We conclude that increased expression of Bcl-2 in adenomas may imply increasing protection against apoptosis during the progression from mild to severe dysplasia. Reduced expression of Bcl-2 may be due to downregulation by mutant p53 and may mark the point of transition from adenoma to carcinoma.
Hao
X P
XP
Academic Department of Pathology, St Mark's Hospital, Harrow, UK.
Ilyas
M
M
Talbot
I C
IC
D000236:Adenoma / Q000378:metabolism* / Q000473:pathology; D017209:Apoptosis; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D018450:Disease Progression; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000276:immunology; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis* / Q000276:immunology
D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53