Candidate biomarkers identified in the saliva of patients with pancreatic adenocarcinoma.

173 Background: There is currently no simple test to identify patients with pancreatic ductal adenocarcinoma (PDAC). The goal of this research is to develop such a method. We hypothesized that the salivary proteome of patients with localized PDAC contains a protein set distinct from normal subjects. Methods: We collected, processed and stored stimulated whole salivary gland secretions from patients with Stage I-II PDAC and aged-matched healthy volunteers. Fluorescently-labeled proteins were separated using 2D DIGE. Overlay imaging techniques compared 2D DIGE results, and spots representing individual proteins were quantified by signal, isolated from the gels, processed and protein identified using MALDI-TOF Mass Spectrometry. The SWISS-PROT database was used to identify proteins, and the ratio of signal in cancer versus normal samples was quantified and compared using Student’s t-test. Results: Samples from 10 PDAC patients and 10 healthy subjects were compared. A total of 96 spots on the 2D-DIGE comparison were uniquely present or absent in PDAC patient saliva. MALDI-TOF Mass Spectrometry examination of these 96 characterized 53 unique proteins. After eliminating duplicates and proteins without significant differences (p-value <0.02), a total of 30 proteins were identified with levels higher (n=18) or lower (n=12) in saliva from PDAC patients versus normal subjects. Conclusions: Examination of saliva from pancreatic cancer patients identified a set of proteins unique from normal subjects. These proteins represent targets for the development of biomarkers that could be used in early detection of pancreatic cancer.