Protein profiling in pancreatic juice for detection of intraductal papillary mucinous neoplasm of the pancreas.

BACKGROUND/AIMS: Malignant intraductal papillary mucinous neoplasm of the pancreas (IPMN) has a very poor prognosis, and there is no useful biomarker for an early diagnosis at present. A biomarker is expected to allow an early diagnosis of IPMNs and consequently lead to an improvement of the patients' prognosis. Recent advances in proteomic analysis are remarkable; therefore we explored novel biomarkers for IPMN using Surface-Enhanced Laser Desorption and Ionization (SELDI) Mass Spectrometry.

METHODOLOGY

We collected pancreatic juice samples from 33 patients with IPMNs, 54 patients with pancreatic ductal carcinoma, and 31 with chronic pancreatitis. We analyzed the pancreatic juice samples using a SELDI ProteinChip system (Ciphergen Biosystems, Fremont, CA).

RESULTS

We identified a 6240-Da peak whose expression in pancreatic juice from patients with IPMNs was significantly higher compared with that in other pancreatic diseases (P<0.01). This 6240-Da protein was partially purified and was identified as pancreatic secretory trypsin inhibitor (PSTI) by amino acid sequencing. The pancreatic juice PSTI levels, as measured by radioimmunoassay, were significantly higher in the IPMN group than in the other groups (P<0.001). When the diagnostic cutoff value of PSTI in pancreatic juice was set at 25000 ng/mL, the positive predictive value, negative predictive value, sensitivity, and specificity were respectively 89%, 83%, 48%, and 98%.

CONCLUSIONS

PSTI levels of pancreatic juice in patients with IPMN were significantly higher than those in patients with other pancreatic diseases. The PSTI level in pancreatic juice may be useful for the diagnosis of IPMN.