Postprandial cell proliferation in the esophageal epithelium of rats

Immunohistochemical examination of gastrin, gastrin precursors, and gastrin/CCK-2 receptor in human esophageal squamous cell carcinomas

A promoting effect of gastrin on stimulating Barrett's oesophagus proliferation has been demonstrated, but whether it plays a regulating role for esophageal squamous cell carcinoma (ESCC) to date has not been fully investigated. The aim of this study is to examine the expressions of gastrin, gastrin precursors and gastrin/CCK-2 receptor in ESCC. Tissue specimen sections from 38 patients with ESSC obtained from a high incidence area of north China were assessed using immunohistochemistry for amidated gastrin, gastrin precursors (progastrin and glycine-extended gastrin) and gastrin/CCK-2 receptors. Their clinical histopathological significance was also analyzed. Of 38 ESCC, the immunoreactivities of gastrin, glycine-extended gastrin and progastrin were observed in 13.2% (5/38), 7.9% (3/38) and 23.68% (9/38) cases. The expression of progastrin was obviously higher than other gastrins, though not significantly (P > 0.05). In positive cases for gastrin or glycine-extended gastrin, the scores of positive tumor cell numbers were at a lower density (<10/abundant-distributed field). However, the scores of progastrin positive tumor cell density in five of nine positive cases were over 10/abundant-distributed field. The immunoreactivity of gastrin/CCK-2 receptor was also observed in 15.8% (6/38) ESCC cases. There was not significant correlation regarding immunohistochemical results with known histomorphological parameters i.e. gender, tumor location and TNM stages. Based on our current results, ESCC tumor cells could be a possible cellular source of gastrin precursors, which has been postulated to play a role in regulating the growth in some human tumor cells.

Gastrin stimulates receptor-mediated proliferation of human esophageal adenocarcinoma cells

The prevalence of esophageal adenocarcinoma in the setting of Barrett's metaplasia continues to increase in Western nations at a rate greater than any other cancer. The trophic properties of gastrin have been documented in gastric, pancreatic and colon cancer cell lines, suggesting a potential role for this regulatory peptide in the growth of these malignancies. The aims of these studies were to identify and characterize the presence of functional cholecystokinin type-2 (gastrin) receptors on the membranes of human esophageal adenocarcinoma cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated the presence of cholecystokinin type-2 receptor transcripts in human esophageal adenocarcinoma cell lines. Competitive binding assays revealed specific binding of gastrin in SEG-1 cells (IC50 of 2.4 x 10(-8) M). This finding was confirmed by laser scanning confocal microscopy through internalization of rhodamine green labeled gastrin heptapeptide in SEG-1 cells. Gastrin caused a dose-dependent increase in proliferation of SEG-1 cells when compared to controls. This effect was abolished by co-incubation with L365,260, a CCK-2-specific receptor antagonist. Gastrin-induced phosphorylation of the p44 and p42 mitogen-activated protein kinases was demonstrated by Western blot analysis. In conclusion, the studied human esophageal adenocarcinoma cell lines possess cholecystokinin type-2 (gastrin) receptors. Receptors bind gastrin, resulting in increased proliferation in SEG-1 cells.