Abstract
The expression of P‐cadherin, one of the Ca^2+^‐dependent cell‐cell adhesion molecules, in human gastric carcinomas was examined by Northern blotting, Western blotting and immuno‐histochemistry. P‐cadherin mRNA was expressed in all the gastric carcinoma tissues examined, whereas no message was detected in non‐neoplastic mucosa. By Western‐blot analysis, P‐cadherin protein was expressed in 83% and 29% of the well‐differentiated and poorly differentiated gastric adenocarcinomas, respectively, the incidence being significantly different. Immunohistochemically, P‐cadherin immunoreactivity was localized on the cell surface or the cell‐to‐cell borders of well‐differentiated adenocarcinomas. P‐cadherin was not detected in Borrmann's type‐4 or scirrhous carcinomas where the tumor cells proliferate diffusely with productive fibrosis. The level of P‐cadherin expression in stage‐2 carcinomas was significantly higher than in stage‐1 carcinomas. In the case of patients in stages 2 to 4, however, the level of P‐cadherin expression decreased as the stage progressed, the difference between stages 2 and 3 and between stages 3 and 4 being significant. Our findings suggest that P‐cadherin might play an important role in the development of well‐differentiated gastric adenocarcinomas and the decreased expression of P‐cadherin might be responsible for the infiltrative growth and progression of gastric carcinomas.