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Background/Aims--Granding of Helicobacter pylori induced atrophic gastritis using the updated Sydney system is severely limited by high interobserver variability. The aim of this study was to set up a quantitative [...]

Background: Patients with Barrett's oesophagus (80) are at risk of oesophageal adenocarcinoma. Because the pattern of mucosal mucins changes during neoplastic progression, it may serve as a marker of intraepithelial neoplasia. Aims: To determine the expression pattern of mucins in neoplastic 80 epithelium (high grade dysplasia) and correlate it with the expression of apoptosis markers Sax and Bcl-2. Methods: Thirty seven patients with 80 were studied: 16 without introepithelial neoplasia, six with high grade intraepithelial neoplasia (HGN), and 15 with infiltrating adenocarcinoma. Biopsies were obtained from squamous epithelium, Barrett's epithelium, and (when present) foci of suspected HGN or adenocarcinoma. MUC1-4, MUC5AC, MUC5B, MUC6, Bax, and Bcl-2 mRNA were determined by semiquantitative RT-PCR. MUC2, MUC5AC, and MUC6 protein was determined by immunoblotting. Results: Mucin expression varied between neoplastic progression stages in 80. Mucin mRNA levels were low in squamous epithelium, except for MUC4, and were at least four times higher in 80 and HGN (p<0.001), but less so in adenocarcinoma. MUC4 expression was significantly lower in 80 than in normal squamous epithelium, whereas in HGN and adenocarcinoma, levels were significantly higher than in BO (p = 0.037). The Bax:Bcl-2 ratio was increased in HGN compared with 80 (p = 0.04). MUC2, MUC5AC, and MUC6 protein values correlated with mRNA data. Conclusions: Mucin expression varies during the development of oesophageal adenocarcinoma in BO. MUC4 could serve as a tumour marker in this process. In contrast to animal studies, upregulation of MUC4 in HGN is associated with increased apoptosis, suggesting that MUC4 plays a minor role in apoptosis regulation in 80. [ABSTRACT FROM AUTHOR]