pS2 expression as a possible diagnostic marker of colorectal carcinoma in ulcerative colitis.

This study was performed to evaluate the significance of pS2 and MUC1 expressions in ulcerative colitis (UC)-associated colorectal neoplasias. Tissues were collected from 6 patients with UC-associated colorectal neoplasias treated surgically. Specimens were 13 adenocarcinomas, 40 dysplasias (20 high-grade dysplasias, 20 low-grade dysplasias), and 60 normal mucosae. Tissues were also collected from patients without UC treated surgically or endoscopically. pS2, p53, and MUC1 expressions were examined immunohistochemically and compared. The K-ras codon 12 mutation was investigated by single-strand conformation polymorphism analysis. In patients with UC, the incidence of pS2 expression was significantly higher (p<0.01) in adenocarcinomas than it was in dysplasias, and no pS2 expression was seen in normal mucosae. p53 overexpression was detected in 50% (10/20) even in low-grade dysplasias. MUC1 expression was seen only in invasive carcinomas, but it was seen in 100% of cases (3/3). K-ras gene mutations were detected in 2 (20%) of 10 carcinomas. In low and high-grade dysplasias, the incidences of pS2 expression were significantly (p<0.01) lower than the incidences of p53 overexpression, however, in UC-associated carcinomas there was no significant difference; pS2 expression and p53 overexpression were detected in 13 of 13 (100%) cases and in 12 of 13 (92%) cases, respectively. These results suggest that p53 overexpression may be a diagnostic marker of neoplasia, and that pS2 expression may be a diagnostic marker of colorectal carcinoma in case of UC.