Expression of the coiled coil domain containing protein 116 in the pancreatic islets and endocrine pancreatic tumors

Aims: Coiled coil domain containing protein 116 (CCDC116) is a product of the gene coiled coil domain containing 116 located on human chromosome 22. Its function has not yet been established. The present study focuses on the expression of this protein in human pancreatic islets and in the endocrine pancreatic tumors (EPTs). Methods and Results: Expression of the protein was evaluated by immunohistochemistry in endocrine pancreas from six patients and in various EPTs from 51 patients. In pancreatic islets, virtually all insulin, approx. 75% of the somatostatin, and approx. 60% of the pancreatic polypeptide (PP) cells were immunoreactive for the CCDC116 protein whereas glucagon, ghrelin and the exocrine cells were not. All insulinomas, gastrinomas, non-functioning sporadic tumors and the hereditary multihormonal EPTs were immunoreactive with variable relative incidence. Two of the three somatostatinomas, and one of the three ACTH-secreting tumors also expressed CCDC116. Conclusions: The CCDC116 protein is expressed in all islet cell types except the glucagon and ghrelin cells. Most of the EPTs also contained CCDC116 protein. These findings suggest that this protein may play some role for the above mentioned endocrine cells and tumors. Its function has to be investigated in future studies.