Abstract
Abstract Esophageal carcinogenesis is a multistage process characterized by morphological changes from normal esophagus to basal cell hyperplasia, dysplasia, carcinoma in situ and squamous cell carcinoma (SCC). Our laboratory has used a rodent model of N-nitrosomethylbenzylamine (NMBA)-induced esophageal SCC to investigate molecular carcinogenesis and identify putative chemopreventive agents. In our previous studies, we found that the expression of cyclooxygenase-2 and the production of prostaglandin E2 (PGE2) in rat esophageal epithelium were elevated in papillomatous lesions relative to precancerous and normal tissues. PGE2 exerts its cellular effect by binding to its cognate receptors. There are four subtypes of PGE2 receptors, EP1, EP2, EP3 and EP4, which are involved in carcinogenesis depending on the cell or tissue types. The overall objective of the current study was to assess the roles of PGE2 receptors in NMBA-induced rat esophageal tumorigenesis. F344 rats were injected subcutaneously with NMBA (0.30 mg/kg b.w.) three times per week for five weeks. One week after NMBA treatment, animals were randomized into five experimental groups and fed 300 ppm celcecoxib plus 50 ppm S,S'-1,4-phenylenebis(1,2-ethanediyl)bisisothiourea (PBIT) starting from week 6, 9, 12 , or 15, respectively, or 5% freeze-dried black raspberries (BRB) starting from week 6. Esophagi were collected at 29 weeks. Results of real-time PCR, western blot analysis and immunohistochemistry demonstrated a correlation between the upregulation of EP1, EP2, EP3 and EP4 and neoplastic progression in the rat esophagus. The expression of the PGE2 receptors in preneoplastic tissues and papillomas was significantly elevated when compared to normal tissues. Moreover, we observed that celecoxib + PBIT and 5% BRB significantly reduced EP2 expression. Our data suggest, therefore, that the production of PGE2 receptors by the esophageal epithelium is associated with the development of NMBA-induced esophageal tumorigenesis in rats, and EP2 antagonist may have chemopreventive potential in esophageal cancer. Research efforts are needed to elucidate the function of PGE2 receptors and related oncogenic pathways in esophageal SCC. (Supported by NIH/NCI R01 CA131073-01A1). Citation Format: Ni Shi, Tong Chen. Assessment of the roles of prostaglandin E2 receptors in a rodent model of chemically induced esophageal carcinogenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1247. doi:10.1158/1538-7445.AM2014-1247
Published Version
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