Overexpression of the Sm-like proto-oncogene in primary and metastatic pancreatic endocrine tumors

CONTEXT: The cancer associated Sm-like proto-oncogene mRNA has been found to be overexpressed in the majority of pancreatic adenocarcinomas and is necessary for the transformed phenotype in pancreatic cancer cell lines. However, expression levels have not been examined in other types of pancreatic neoplasms, such as pancreatic endocrine tumors. SETTING: Fifteen primary pancreatic endocrine tumors, including five insulinomas and 10 non-functioning tumors, along with seven hepatic metastatic pancreatic endocrine tumors. MAIN OUTCOME MEASURES: Quantitative expression levels of cancer associated Sm-like mRNA were measured by real-time PCR. Overexpression was defined as a two-fold or greater value when compared to the expression levels found in normal pancreatic islet cells obtained from healthy donors. RESULTS: In primary tumors, four of the 10 non-functioning pancreatic endocrine tumors were found to overexpress cancer associated Sm-like mRNA (40%). Three of the five (60%) insulinomas also overexpressed cancer associated Sm-like mRNA. In total, cancer associated Sm-like mRNA was overexpressed in seven of 15 primary tumors (47%) and in the majority (71%, 5 of 7) of the hepatic metastases. CONCLUSIONS: Our results indicate that the cancer associated Sm-like mRNA gene may also play a role in the tumorigenesis of pancreatic endocrine tumors.