Distribution of cell populations with DNA aneuploidy and p53 protein expression in ulcerative colitis

Patients with ulcerative colitis are at an increased risk for developing colorectal neoplasms. p53 mutations and the occurrence of DNA aneuploidies are common events in the development of sporadic colorectal neoplasias. This study tried to determine the frequency of these events during the development of colitis-associated colorectal neoplasms.

Four colectomy specimens with a total of 124 biopsies were investigated. DNA content was measured by flow cytometry and p53 protein expression was detected by immunohistochemistry. These results were correlated with histological findings.

DNA aneuploidies were found in 58 (46.8%), and p53 protein expression in 30 samples (24.2%). The presence of DNA aneuploidy as well as of p53 protein expression correlated with the histological characteristics of neoplastic transformation. In areas without dysplasias or with indefinite dysplasias, 31.5% of the samples showed DNA aneuploidies and in about 9% of the samples p53 protein expression could be detected; 33.7% of samples without or with indefinite dysplasias showed p53 protein expression and/or DNA aneuploidies.

These results show that the occurrence of DNA aneuploidies and nuclear p53 protein expression is a common event in the development of colitis-associated colorectal neoplasias. p53 protein expression seems to be an early event in this process. DNA aneuploidies occur even earlier and more frequently in the absence of p53 protein expression. Therefore, other genetic alterations besides p53 gene mutations might be involved in colitis-associated tumour development.