Accumulation of beta-catenin protein and mutations in exon 3 of beta-catenin gene in gastrointestinal carcinoid tumor

The molecular basis of carcinogenesis in gastrointestinal carcinoid tumors is not well understood. To clarify the contribution of the Wnt/beta -cateni n signaling to this type of carcinogenesis, we investigated 72 cases of gas trointestinal carcinoid tumor both immunohistochemically and by direct sequ encing or beta -catenin. Accumulation of beta -catenin in the cytoplasm and /or nucleus was observed in 57 cases (79.2%). We also detected mutations in exon 3 of beta -catenin in 27 cases (37.5%) and one mutation in APC (1.4%) . Our results suggest that alterations in the Wnt/beta -catenin signaling p atb,hay may be involved in the development of gastrointestinal carcinoid tu mors.