Expression of E-cadherin catenin and C-erbB-2 gene products in invasive ductal-type breast carcinomas

Special attention has focused on E-cadherin and the invasiveness of breast carcinoma because E-cadherin was suggested to be the major cell adhesion molecule in the mammary gland. In the cytoplasm, E-cadherin is linked to beta-catenin and alpha-catenin which mediate the connection of the cytoskeleton. In addition, c-erbB-2 oncoprotein causes disruption of this cell adhesion system through beta-catenin phosphorylation. We investigated the expression of E-cadherin, alpha-catenin and c-erbB-2 gene products in 66 invasive ductal carcinomas by immuno-histochemistry to examine the relation between the E-cadherin mediated cell adhesion system and histological subtypes used in Japan as well as histological grading. The series included 21 papillotubular carcinomas, 16 solid-tubular carcinomas and 29 scirrhous carcinoma. There were 33 cases of grade I, 20 cases of grade II and 13 cases of grade III. We defined P&P&N as E-cadherin positive and alpha-catenin positive and c-erbB-2 negative cases to evaluate the preservation of the E-cadherin mediated cell adhesion system. There were only 13 cases (19.7%) of P&P&N in total. As for the frequency of E-cadherin/alpha-catenin/c-erbB-2 expression and P&P&N, no significant difference between histological subtypes was found. However, those in the grade I group tended to be higher than in the other two grade groups. Regarding the rates of alpha-catenin positive cases and P&P&N cases, there were significant differences between the grade I group and a combination group consisting of the grade II and grade III groups. These results suggest that the E-cadherin-mediated cell adhesion system is frequently lost in invasive ductal-type breast cancers by random loss of E-cadherin/catenins or c-erbB-2 overexpression, and that the preservation of this system correlates with well differentiated morphological features.