Mutation of beta-catenin and its protein accumulation in solid and cystic tumor of the pancreas associated with metastasis.

Beta-catenin serves not only as a structural component of the E-cadherin-mediated cell-cell adhesion system, but also as a signaling molecule of the Wnt/wingless pathway. Mutations of beta-catenin and aberrant expression of its protein have been identified in a number of different types of human malignancies. To determine the role of beta-catenin in solid and cystic tumor (SCT) of the pancreas, a rare neoplasm usually observed in young females, we examined three primary tumors and one corresponding liver metastatic tumor presented in pediatric patients. Single strand conformation polymorphism and neucleotide sequencing analysis confirmed a TCT right curved arrow TTT somatic mutation at codon 37 changing serine to phenylalanine in one of the primary tumors and its corresponding metastatic tumor. Immunohistochemical analysis displayed abnormally strong nuclear and widespread cytoplasmic expression of beta-catenin in these tumors with the mutation. Our observations suggest that, in some SCTs of the pancreas presented in the pediatric age group, mutated beta-catenin has an important oncogenic effect.