Expression of glucagon-like peptide 1 receptor and its effects on biologic behavior in pancreatic neuroendocrine tumors

OBJECTIVES: Glucagon-like peptide 1 (GLP-1) interacts with its specific high-affinity receptor, glucagon-like peptide 1 receptor (GLP-1R), and induces cellular growth and inhibition of apoptosis in pancreatic β cells. The aim of this study was to investigate the significance of GLP-1R expression in pancreatic neuroendocrine tumors (PNETs). METHODS: Glucagon-like peptide 1 receptor expression was semiquantitatively evaluated by immunohistochemical staining in 50 resected PNETs, and the correlation between the GLP-1R expression and clinicopathologic features was investigated. RESULTS: There were 23 PNETs with positive expression and 27 PNETs with negative expression of GLP-1R. Positive expression of GLP-1R was more frequently observed in insulinoma than in gastrinoma and nonfunctioning tumor (P < 0.05). Although expression status of GLP-1R did not affect the prognosis of the patients with PNETs (P = 0.82), most of the metastatic sites such as lymph node and liver showed positive staining for GLP-1R (8 of 11 PNETs, 73%). CONCLUSIONS: Glucagon-like peptide 1 receptor would be a diagnostic marker of insulinoma and might become a molecular target for treatment of metastatic PNETs and hormonal regulation of insulin.