Immunohistochemical analysis of REG Iα expression in ulcerative colitis-associated neoplastic lesions.

ABSTRACT

BACKGROUND AND AIMS: The regenerating gene (REG)Iα has been identified by microarray analysis as a gene that is distinctly overexpressed in ulcerative colitis (UC), and its protein product is suggested to play a pivotal role in the development of UC-associated carcinoma. In the present study, we investigated the significance of REG Iα expression as a diagnostic marker of UC-associated neoplasia. METHODS: Tissue samples were obtained from colectomy specimens from 31 patients with long-standing UC (mean disease duration 17.2 years, range 5-29). The lesions were evaluated according to the International Classification for Dysplasia in Inflammatory Bowel Diseases, and the sections were examined using immunohistochemistry for REG Iα and p53. RESULTS: In the 'regenerating atypia' group, REG Iα immunoreactivity was restricted to the lower third of the UC mucosa (grade 1). Lesions classified as 'indefinite for dysplasia' also showed predominantly basal-type staining for REG Iα. However, in 'low-grade dysplasia' and 'high-grade dysplasia' lesions, the localization of REG Iα immunoreactivity expanded to the middle (grade 2) and upper (grade 3) third of the UC mucosa, respectively. The REG Iα immunostaining pattern differed significantly (p < 0.0001) between non-neoplastic and neoplastic lesions, and was significantly (p < 0.0001) associated with p53 overexpression. CONCLUSIONS: Immunohistochemical analysis of REG Iα expression is useful for differential diagnosis of non-neoplastic and neoplastic lesions in UC tissues.