ALTERED GAP JUNCTIONAL INTERCELLULAR COMMUNICATION IN NEOPLASTIC RAT ESOPHAGEAL EPITHELIAL-CELLS

Gap junctional intercellular communication (GJIC) is reduced in many n eoplastic cells, but few data exist for esophageal neoplasms. GJIC was examined by fluorescent dye microinjection in two nontumorigenic and two highly tumorigenic rat esophageal epithelial cell lines, All lines expressed high levels of dye coupling in homologous cell culture, In cocultures of nontumorigenic and tumorigenic cells, however, only one of six cell combinations displayed significant heterologous GJIC, Nort hern, Western, and immunohistochemical analyses indicated that all fou r cell lines expressed comparable levels of connexin43 (Cx43), but not connexin32 or connexin26, and formed Cx4S-containing gap junction pla ques at cell-cell interfaces, Immunostaining of rat esophageal frozen sections demonstrated that esophageal epithelial cells expressed Cx43 in vivo. In normal epithelium, the highest expression was seen in the basal cells and little suprabasal staining was evident, In preneoplast ic and neoplastic lesions of the esophageal epithelium which were indu ced by treating rats with N-nitrosomethylbenzylamine, Cx43 staining of the basal layer was also seen but appeared to be more diffuse compare d to normal epithelium. In addition, suprabasal Cx43 staining was appa rent in dysplastic and papillomatous lesions, These results indicate t hat Cx43 is expressed in normal and neoplastic rat esophageal cells an d that the cells exhibit extensive homologous GJIC, but little heterol ogous GJIC. This lack of heterologous GJIC may be due to differences i n cell adhesion proteins or other factors.