Measurement of urinary kininogen (KNG) fragments as a noninvasive tool for early diagnosis of pancreatic cancer (PaCa).

Abstract

209 Background: There is a clear need to identify a non-invasive biomarker for early diagnosis of PaCa, in order to improve the overall survival of PaCa patients. Secretion of large amounts of proteases is a hallmark of PaCa, which results in an abundance of protease-induced cleavage products being excreted in the urine. This has led to speculation that measurement of PaCa-specific fragments in the urine might be useful as a tool for discrimination between PaCa patients and healthy controls. Herein, we introduce urinary KNG fragments as a promising biomarker for early diagnosis of PaCa. Methods: Urine samples were collected from PaCa patients and healthy volunteers, with the written informed consent, from January 2014 to July 2016. Urinary protein tryptic fragments derived from protein C-termini were measured using isobaric tags (iTRAQ) for their relative quantitation, and the diagnostic ability of the urinary levels of these fragments was evaluated by receiver operating characteristic (ROC) curve analysis. The fragments which showed an area-under-the-curve (AUC) of over 0.8 were selected as candidate fragments for further validation by the multiple-reaction-monitoring technique (MRM) combined with high-speed liquid chromatography. The urinary level of each candidate fragment was quantified by MRM, and the diagnostic capability of each for discriminating PaCa patients from healthy controls was evaluated by ROC curve analysis. Results: Urine samples of 39 PaCa patients (7 resectable, 32 unresectable) and 42 healthy controls were examined by iTRAQ to find 12,783 fragments. ROC curve analysis was carried out to select two candidate fragments (fragments A, B), both of which turned out to be KNG cleavage products. The urinary levels of the two fragments were measured in 23 resectable PaCa, 118 unresectable PaCa patients, and 42 healthy volunteers using high-speed-LC-/MRM. The AUCs of serum CA19-9 and urinary levels of fragments A and B for discriminating patients of PaCa from healthy controls were 0.89, 0.81 and 0.70, respectively. Conclusions: Urinary KNG fragments showed favorable diagnostic capability and were considered as promising, noninvasively measurable biomarkers of PaCa.