Altered expression of β-catenin and c-erbB-2 in early gastric cancer

To investigate the possible relationship between altered expression (loss of membranous staining or nuclear accumulation) of β-catenin and invasion/metastasis in early gastric cancer (EGC), β-catenin was detected immunohistochemically in 116 cases of EGC, including 86 differentiated and 30 undifferentiated carcinomas. In parallel, immunohistochemical expression of c-erbB-2 was analyzed in all EGC cases. Regardless of histological type, altered expression of β-catenin was found in 47% of mucosal carcinomas and 89% of carcinomas with submucosal invasion (p<0.001). Of particular interest is that β-catenin alteration was found in almost all EGCs with lymph node metastasis, even though no significant statistical comparison could be made. These results suggest that molecular changes resulting in abnormal β-catenin expression participate in the process of submucosal invasion and metastasis. While loss of expression was preferentially observed in undifferentiated EGCs, nuclear accumulation was found exclusively in 24% of differentiated EGCs. c-erbB-2 was overexpressed in only 16% of differentiated EGCs but there was no correlation between this overexpression and invasion or metastasis. However, it is intriguing that 12 out of 14 cases with c-erbB-2 overexpression also showed altered β-catenin expression, suggesting that both molecules are involved in the development of a certain set of differentiated EGCs.