The incidence of adenocarcinoma of the esophagus has been increasing in developing countries over the last three decades and probably reflects a genuine increase in the incidence of its recognized precursor lesion , Barrett's metaplasia. Despite advances in multimodality therapy , the prognosis for invasive esophageal adenocarcinoma is poor. An improved understanding of the molecular biology of this disease may allow improved diagnosis , therapy , and prognosis. We focus on recent developments in the molecular and cell biology of Barrett's metaplasia , a heterogeneous lesion affecting the transitional zone of the gastro-esophageal junction whose associated molecular alterations may vary both in nature and temporally. Early premalignant clones produce biological and genetic heterogeneity as seen by multiple p53 mutations , p16 mutations , aneuploidy , and abnormal methylation resulting in stepwise changes in differentiation , proliferation , and apoptosis , allowing disease progression under selective pressure. Abnormalities in expression of growth factors of the epidermal growth factor family and cell adhesion molecules, especially cadherin/catenin complexes , may occur early in invasion. Exploitation of these molecular events may lead to a more appropriate diagnosis and understanding of these lesions in the future. (Am J Pathol 1999, 154:965-973)
Duodenal ulcers are associated with gastric metaplasia in the duodenum, both at the ulcer margin and at more distant sites in the duodenal bulb. pS2 and human spasmolytic polypeptide (hSP) are secretory peptides expressed in gastric epithelial ceils and in gastric metaplasia. As these peptides may be important in ulcer healing, this study investigated the possibility that the expression ofpS2 and hSP is increased in gastric metaplasia at the margin ofduodenal ulcers. (SEM), 20.6 (3.3) v 9.5 (3.0); p<0.001). There was a trend towards greater hSP staining at the ulcer margin but this did not achieve statistical significance. These findings support the putative role of pS2 and possible hSP in mucosal healing and providy further evidence for an autocrine 'ulcer-gastric metaplasia-repair' loop involving these trefoil peptides.
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