Tricellulin expression in normal and neoplastic human pancreas

Aims: Tricellulin is a member of the family of tight junction proteins, which are found concentrated mainly at tricellular contacts. Altered expression of several tight junction components has been observed during carcinogenesis. In the present study, we have analysed the expression of tricellulin in normal human pancreas, and in primary exocrine and endocrine pancreatic tumours. Methods and results: A total of 96 cases were studied: 20 normal pancreas, 58 pancreatic ductal adenocarcinomas, 15 pancreatic endocrine neoplasms, and three acinar cell carcinomas. Immunohistochemistry (analysed by digital morphometry), immunofluorescence, western blot analysis and reverse transcription polymerase chain reaction were performed. Tricellulin was localized apically in normal ducts and acini as intensive, spotty immunopositivity at tricellular contacts, whereas weaker signals were observed at the junction between two cells. Islets of Langerhans were negative. Well-differentiated ductal adenocarcinomas significantly overexpressed tricellulin as compared with poorly differentiated adenocarcinomas. Acinar cell carcinomas expressed tricellulin in tumour cells. All endocrine tumours were tricellulin-negative. Conclusions: This is the first report to describe the tricellulin expression profile in normal and neoplastic human pancreas. Both normal and neoplastic pancreatic exocrine tissues expressed tricellulin, whereas no expression was seen in normal or neoplastic endocrine cells. Tricellulin expression in pancreatic ductal adenocarcinomas showed a significant negative correlation with the degree of differentiation.