DIFFERENTIAL EXPRESSIONS OF MRNA IN TUMOR PROGRESSION OF PANCREATIC DUCTAL CARCINOMA AND INTRADUCTAL PAPILLARY MUCINOUS NEOPLASM

Abstract

Background and Aim: Recent microarray analyses suggested that various novel genes were up-regulated in pancreatic ductal carcinoma and intraductal papillary mucinous neoplasm (IPMN). In the present study, we quantitatively measured the mRNA expression of such genes in microdissected cells of normal ducts, PanINs, IPMNs, and invasive pancreatic cancer (IDC) by real time RT-PCR. Furthermore, we evaluated mRNA expression in pancreatic juice samples from patients with chronic pancreatitis, IPMN or IDC. Method: We designed gene-specific primers of MUC1, MUC5AC, S100P, S100A6, S100A11, Twist, and house keeping genes of beta-actin and 18SrRNA. We used one-step real time RT-PCR with gene-specific priming, short amplicons, and normalization to house keeping genes to achieve reliable quantification of mRNA from moderately to extensively fragmented samples of microdissected cells or pancreatic juice. After histological evaluation on H&E stained sections, normal duct cells, PanIN cells (PanIN 1B or PanIN 2), IPMN cells (IPM adenoma or IPM borderline), and IDC cells were isolated selectively from frozen sections with a laser microdissection and pressure catapulting system. Result: All six genes showed significantly higher expressions in IDC cells than in normal duct. Stepwise up-regulations were observed in MUC5AC, MUC1, S100A6 and Twist in relation to the tumor progression of pancreatic ductal carcinoma, from normal duct to PanINs and IDC. Levels of S100P mRNA in PanINs were comparable to those of IDC, and that of S100A11 was significantly higher in PanINs than in IDC. Meanwhile, MUC5AC, S100P and S100A11 showed significantly higher expression in IPMN than in IDC. Twist expression was significantly lower in IPMN than in IDC. Expression of mRNA in pancreatic juice was similar to that in microdissected cells, and Twist was most useful to differentiate pancreatic cancer from IPMN. Conclusion: Quantitative measurement of mRNA levels of these genes was successfully achieved in microdissected target cells from pancreatic tissues and differential expressions were observed in pancreatic cancer and IPMN. These genes may become promising diagnostic markers and therapeutic targets for pancreatic cancer.