NPTX2 hypermethylation in pure pancreatic juice predicts pancreatic neoplasms

The neuronal pentraxin II (NPTX2) gene is methylated in over 90% primary pancreatic cancer tissues but rarely in normal pancreatic ductal epithelia. Here, the authors investigated the utility of methylated NPTX2 as a diagnostic marker for pancreatic cancer in pure pancreatic juice samples of patients with benign and malignant pancreatic diseases, including pancreatic cancer, intraductal papillary mucinous neoplasm or chronic pancreatitis using methylation-specific polymerase chain reaction (MSP) and quantitative MSP. MSP assays revealed that the incidence of aberrant NPTX methylation in pure pancreatic juice samples was 64.5% (20 of 31) in patients with pancreatic cancer, 70.0% (7 of 10) in patients with malignant intraductal papillary mucinous neoplasm, 33.3% (2 of 6) in patients with benign intraductal papillary mucinous neoplasm and 21.7% (5 of 23) in patients with chronic pancreatitis. NPTX2 hypermethylation in patients with chronic pancreatitis was significantly lower than that of pancreatic cancer (P < 0.01) or patients with intraductal papillary mucinous neoplasm (P < 0.05). At a cutoff value of 1.39 for quantitative MSP, the incidence of aberrant NPTX2 methylation was 61.3% (19 of 31) in patients with pancreatic cancer, 50.0% (5 of 10) in patients with malignant intraductal papillary mucinous neoplasm, 0% in patients with benign intraductal papillary mucinous neoplasm and 8.7% (2 of 23) in patients with chronic pancreatitis. There was a significant difference in NPTX2 methylation between pancreatic cancer and chronic pancreatitis (P < 0.01). Our findings indicate that detection of aberrant methylation of NPTX2 in pure pancreatic juice samples could be useful as a molecular marker to discriminate between patients with malignant and benign disease of the pancreas.