Immunohistochemical expression of 14-3-3 sigma protein in intraductal papillary-mucinous tumor and invasive ductal carcinoma of the pancreas.

BACKGROUND: 14-3-3 sigma (sigma) has been shown to be overexpressed in pancreatic cancers by a c-DNA microarray technique. However, the expression of 14-3-3 sigma in intraductal papillary-mucinous tumor (IPMT) of the pancreas remains unclear.
MATERIALS AND METHODS: To evaluate the biological importance of 14-3-3 sigma expression in pancreatic carcinogenesis, immunohistochemistry for 14-3-3 sigma, CDX2, MUC1, MUC2, p53, p16 and Ki-67 was carried out on 33 IPMTs and the results were compared with those for 14 invasive ductal carcinomas (IDCs).
RESULTS: The frequency of 14-3-3 sigma immunoreactivity was 70% and 100% in IPMT and IDC, respectively. The frequency of MUCI and Ki-67 immunoreactivity was significantly higher in IDC than IPMT. In IPMT, dark columnar cell types prevailed over clear columnar cell types in terms of the frequency of the Ki-67 labeling index.
CONCLUSION: The overexpression of 14-3-3 sigma was confirmed in both IDC and IPMT. Therefore, this overexpression might occur in the early stages of pancreatic carcinogenesis. Moreover, IPMT composed of dark columnar cells might be a potentially more advanced form than that made up of clear columnar cells.