Integrated p53 histopathologic/genetic analysis of premalignant lesions of the esophagus

Abstract

Esophageal carcinoma frequently occurs in patients with long-standing achalasia.

Aim: To examine the role of p53 alterations and PCNA in patients with megaesophagus.

Methods: Sections of four tumors, and corresponding adjacent areas, from patients with achalasia due to Chagas' disease were examined by immunohistochemistry for p53 and PCNA proteins. Furthermore, 128 biopsies from 16 advanced achalasic patients were prospectively collected and evaluated for grades of inflammation, hyperplasia, dysplasia and also for p53 and PCNA proteins. All specimens showing p53 immunoreactivity were topographically genotyped using microdissection, PCR amplification and direct sequencing of p53 exons 5-8.

Results: Diffuse strong immunoreactivity of p53 was observed in 2/4 tumors. In one patient, the adjacent mucosa also showed strong p53. In the adjacent mucosa, the same areas showing p53 overexpression also had PCNA positive cells. In the prospective group, 7/16 (43.7%) patients or 53/128 (41.4%) biopsies expressed p53. The grade of inflammation was significantly correlated with the presence of positive p53, in patients, p = 0.004 and in biopsies, p < 0.00001. PCNA expression was found in the basal layer of the mucosa, and increased PCNA was associated with p53 overexpression, p = 0.00018. Genotyping detected mutation in exon 6, codon 213 RG, in one patient (1/16, 6.2%).

Conclusions: (1.) p53 alterations, overexpression and mutational change, are an early event in patients with achalasia; (2.) The inflammation frequently seen in these patients appears to be associated with alterations of the p53 protein; (3.) Expression of the tumor suppressor gene is increased in areas showing proliferation.