[MicroRNA expression pattern in intraductal papillary mucinous neoplasm].

BACKGROUND/AIMS: Intraductal papillary mucinous neoplasms (IPMN) are precursor lesions of fatal pancreatic cancer. Physiological function of microRNA is to regulate the stability and translation of mRNA. The aberrant microRNA expression is commonly observed in many cancers. The aim of this study was to analyze the expression pattern of microRNA in IPMN and evaluate the role of the microRNA.

METHODS: Using two paraffin-embedded IPMN tissues, microRNA expression of normal tissue, IPMN adenoma and carcinoma were compared by cDNA-mediated annealing, selection, extension and ligation microarray assay. Using real time PCR, expression levels of aberrantly up-regulated microRNAs were assessed in another 20 IPMNs, four pancreatic cancer cell lines (Panc1, MiaPaCa-2, XPA-3, BxPC-3) and immortalized pancreatic ductal cell line (HPNE). Effect of suppressing highly over-expressed two microRNAs in pancreatic cancer cell lines with anti-microRNA inhibitors were evaluated using CCK-8 assay.

RESULTS: Among aberrantly expressed 122 microRNAs in IPMN, miR-552, miR-25*, miR-183, miR-1300, miR-196a, miR-182*, and miR-30c-1* were consistently increased more than 3-fold. On average, miR-196a and miR-183 increased 10,824 folds and 26,519 folds in four pancreatic cancer cell lines compared with HPNE. These two microRNAs were also over-expressed in 20 IPMNs compared with HPNE. After applying anti-miRNA inhibitors, cell survival of four pancreatic cancer cell lines decreased by 24.5% with anti-miR-196a and by 14.2% with anti-miR-183 on average.

CONCLUSIONS: Aberrant expression of 122 microRNAs was observed in IPMN. Two microRNAs, miR-196a and miR-183-increased in IPMN and pancreatic cancer cell lines compared with immortalized dancreatic ductal cell line. The inhibitions of these microRNAs repressed cell proliferation of pancreatic cancer cell lines. (Korean J Gastroenterol 2011;58:190-200).