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.