HIGH-FREQUENCY OF P53 EXPRESSION IN COLORECTAL ADENOMATOUS POLYPS

Previous studies on p53 protein expression in colonic adenomas showed controversial results. The present study evaluates the p53 expression in colonic adenomas, at different dysplasia degrees, by immunohistoche mical analysis, using a newly introduced monoclonal anti-p53 antibody. Paraffin embedded sections of 48 colorectal adenomas, 5 colonic carci nomas and 11 normal colonic biopsies were studied by immunohistochemic al analysis using a monoclonal mouse anti-p53 antibody (clone DO-1). N ormal colonic mucosa specimens and 5/48 adenomas were found negative f or p53 staining. p53-positive nuclei were less than 10% in 22/48 and b etween 10 and 40% in 15/48 adenomas. In 6/48 adenomas and in 4/5 carci nomas we found a high percentage of p53-positive nuclei ( > 40%). Immu nohistochemical p53-positivity is a common event in colonic adenomas, not dependent on dysplasia degree. It might be the result of p53 wild- type increase, due to the typical genomic instability of colonic adeno mas.