Altered localization of E-cadherin and alpha-catenin in rat esophageal tumors

An alteration in the localization of E-cadherin and its associated proteins has been observed in many epithelial neoplasms. No data exist, however, fo r the expression of these proteins in an animal model system for esophageal cancer or in cultured rat esophageal epithelial cell lines. The present st udy investigated the localization of E-cadherin and its associated protein, alpha-catenin, in rat esophageal epithelial cell lines of differing tumori genic potential; in tumors induced after transplantation of these cell line s into syngeneic hosts; and, in esophageal tumors induced in rats by the ca rcinogen, N-nitrosomethylbenzylamine (NMBA). Immunofluorescent staining of the cultured cell lines revealed staining for both E-cadherin and alpha-cat enin at cell-cell boundaries. Western blot analysis confirmed the membrane- bound localization of E-cadherin and alpha-catenin in the cells. However, t umors induced by these cell lines in syngeneic rats showed reduction in the expression of both E-cadherin and alpha-catenin in the plasma membrane of invasive epithelial cells. Immunohistochemical analysis of NMBA-induced eso phageal neoplasms in rats revealed E-cadherin and alpha-catenin to be abnor mally expressed in poorly differentiated tumors when compared to well diffe rentiated tumors. These results suggest that the microenvironment may have an important role in regulating the expression of these adhesion molecules in rat esophageal epithelial cells, and that alteration in the cellular loc alization of E-cadherin and a-catenin may be indicative of tumor progressio n in NMBA-induced rat esophageal cancer.