Suppression of apoptosis does not foster neoplastic growth in Barrett's esophagus

Esophageal adenocarcinoma often arises in association with metaplastic and dysplastic mucosa in Barrett's esophagus. Derangements in cell cycle control and apoptosis regulation might be responsible for the progression from metaplasia to dysplasia and adenocarcinoma We tested this hypothesis by performing cell cycle analysis, in situ detection of apoptosis, and evaluation for the immunohistochemical expression of proteins involved in proliferation (Ki-67), the control of apoptosis (bcl-2, bcl-x and bax), and cell cycle regulation (retinoblastoma and cyclin D1). We studied 17 randomly selected paraffin-embedded esophagectomy specimens that contained intestinal metaplasia without dysplasia, low-grade dysplasia, high-grade dysplasia, and esophageal adenocarcinoma Compared with gastric controls and intestinal metaplasia without dysplasia, high-grade dysplasia and esophageal adenocarcinoma demonstrated greater numbers of cells in S phase and G2 phase. Comparison of the proliferation index and the apoptotic rate in intestinal metaplasia without dysplasia, low-grade dysplasia, high-grade dysplasia, and esophageal adenocarcinoma showed a statistically significant trend that linked an increasing proliferation index and apoptotic rate with increasing histologic severity (P = .006 and P = .0002, respectively). A statistically significant linear association was found between bcl-x expression, bax expression, and the bcl-2-to-bax expression ratio versus increasing histologic severity (P = .0004, P = .007, and P = .03, respectively). These data support the hypothesis that neoplastic transformation of intestinal metaplastic epithelium in the esophagus might result from sequential changes in the expression of proteins involved in the control of apoptosis and the cell cycle. Furthermore, suppression of apoptosis does not seem to foster neoplastic growth in Barrett's esophagus. These observations will lead to a better understanding of the pathogenesis of esophageal adenocarcinoma and might contribute to enhancing the diagnostic accuracy when presented with dysplastic lesions.