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 mi RNA in situ hybridization, we examined the expression of miR-506 in 113 PDACs and 87 paired normal pancreatic tissues. We evaluated mi R-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 diferentiated PDACs showed higher levels of mi R-506 than the poorly diferentiated ones（P = 0.023）. Moreover, mi R-506 expression was negatively associated with pathologic T category（P = 0.004） and lymph node metastasis（P = 0.033）, suggesting that mi R-506 might inhibit the progression of PDAC.Conclusions： Our results suggest that mi R-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 mi RNA, whose expression can be activated by oncogenic signals in early development to hinder the progression of PDAC.