MicroRNA-506 is up-regulated in the development of pancreatic ductal adenocarcinoma and is associated with attenuated disease progression

Background:MicroRNA?506 (miR?506) has been reported to function in several tumors as a tumor suppressor gene or oncogene. However, the expression and role of miR?506 in pancreatic ductal adenocarcinoma (PDAC) remains unclear. In this study, we aimed to evaluate the phenotype of miR?506 in PDAC. Methods:Using miRNA insitu hybridization, we examined the expression of miR?506 in 113 PDACs and 87 paired normal pancreatic tissues. We evaluated miR?506 expression in PDAC cells, normal pancreatic ducts, and acinus/islands, and we analyzed the associations between miR?506 expression and the clinicopathologic characteristics of PDAC patients. Results:miR?506 expression was higher in PDAC than in matched normal pancreatic ductal cells (P<0.001). On the other hand, the combined group of well and moderately differentiated PDACs showed higher levels of miR?506 than the poorly differentiated ones (P=0.023). Moreover, miR?506 expression was negatively associated with pathologic T category (P=0.004) and lymph node metastasis (P=0.033), suggesting that miR?506 might inhibit the progression of PDAC. Conclusions:Our results suggest that miR?506 either plays a role as an oncogene in the tumorigenesis and a tumor suppressor in the progression or serves as a house?keeping, tumor?suppressing miRNA, whose expression can be activated by oncogenic signals in early development to hinder the progression of PDAC.