Gastroesophageal reflux leads to esophageal cancer in a surgical model with mice

Abstract

Background: Esophago-gastroduodenal anastomosis with rats mimics the development of human Barrett's esophagus and esophageal adenocarcinoma by introducing mixed reflux of gastric and duodenal contents into the esophagus. However, use of this rat model for mechanistic and chemopreventive studies is limited due to lack of genetically modified rat strains. Therefore, a mouse model of esophageal adenocarcinoma is needed.

Methods: We performed reflux surgery on wild-type, p53A135V transgenic, and INK4a/Arf+/- mice of A/J strain. Some mice were also treated with omeprazole (1,400 ppm in diet), iron (50 mg/kg/m, i.p.), or gastrectomy plus iron. Mouse esophagi were harvested at 20, 40 or 80 weeks after surgery for histopathological analysis.

Results: At week 20, we observed metaplasia in wild-type mice (5%, 1/20) and p53A135V mice (5.3%, 1/19). At week 40, metaplasia was found in wild-type mice (16.2%, 6/37), p53A135V mice (4.8%, 2/42), and wild-type mice also receiving gastrectomy and iron (6.7%, 1/15). Esophageal squamous cell carcinoma developed in INK4a/Arf+/- mice (7.1%, 1/14), and wild-type mice receiving gastrectomy and iron (21.4%, 3/14). Among 13 wild-type mice which were given iron from week 40 to 80, twelve (92.3%) developed squamous cell carcinoma at week 80. None of these mice developed esophageal adenocarcinoma.

Conclusion: Surgically induced gastroesophageal reflux produced esophageal squamous cell carcinoma, but not esophageal adenocarcinoma, in mice. Dominant negative p53 mutation, heterozygous loss of INK4a/Arf, antacid treatment, iron supplementation, or gastrectomy failed to promote esophageal adenocarcinoma in these mice. Further studies are needed in order to develop a mouse model of esophageal adenocarcinoma.

Figure 1

Surgical produces producing gastroesophageal reflux. (A) esophagogastroduodenal anastomosis; (B) esophagogastroduodenal anastomosis plus gastrectomy.

Figure 2

Average body weight of A/J mice after surgery. Non-operated control mice (Group A, -◆-) had the highest body weight.

Figure 3

Histopathology of mouse esophagus after reflux surgery. (A) In the non-operated control group, the basal layer of the epithelium was smooth and the nuclei were in a single line. (B) The epithelium responded to surgery-induced reflux with hyperplasia. Layers of the squamous epithelium increased and papillae were enlarged. (C) After long-term reflux, the epithelial cells started to lose their polarity with condensed nuclei and increased mitosis. (D) Later on, the squamous epithelium lost its normal architecture. Dysplastic cells penetrated the basal membrane and invade into the stroma. (E) At 20 weeks after the surgery, mucin-producing cells were observed in the parabasal layer of the squamous epithelium. (F) Alcian blue staining confirmed mucin secretion in these scattered mucinous cells. (G, H) At 80 weeks after surgery, squamous cell carcinoma was observed in the Swiss-rolled esophagus of a mouse in Group B. Panel H is magnification of part of Panel G.

Figure 4

p53 expression in the esophagi of wild-type and p53^A135V mice. Strong nuclear accumulation appeared in the esophageal epithelial cells of p53^A135V mice, suggesting the mutant form of p53 protein.