Proteomics Profiling of Pancreatic Cancer and Pancreatitis for Biomarkers Discovery

Abstract

Pancreatic cancer is one of the most aggressive malignancies with an increase in incidence predicted, particularly in African Americans. Pancreatic cancer is considered a silent disease with poor prognosis and a lack of early biomarkers for detection. Proteomics has been applied in many diseases for identifying or discovering biomarkers. It has long been suggested that chronic pancreatitis may be a risk factor for developing pancreatic cancer. This study identified proteins that are altered in expression in pancreatic cancer and pancreatitis compared to normal using proteomic technology. Proteins were extracted from laser captured micro-dissected tissues and separated in 2-DPAGE and imaged. The protein profiles of pancreatic cancer and pancreatitis are similar but differed with the protein profile of normal adjacent tissues. Representative proteins, overexpressed in tumor and pancreatitis but not normal tissues, were excised from gels, subjected to in-gel digestion, and analyzed by MALDI-TOF mass spectrometry. Proteins identified included transferrin, ER-60 protein, proapolipoprotein, tropomyosin 1, alpha 1 actin precursor, ACTB protein, and gamma 2 propeptide, aldehyde dehydrogenase 1A1, pancreatic lipase and annexin A1. Several proteins, which were shown in pancreatic cancer, were also observed in pancreatitis samples. Understanding the role of these specific proteins and their mechanistic action will give insights into their involvement in pancreatic cancers.

Keywords: 2D-gel; Biomarkers; Lipase; Pancreatic cancer; Pancreatitis; Proteomic.

Figure 1:

Representative images of frozen pancreatic cancer section specimens before and after laser capture microdissection.

Figure 2:

Representative 2-DE gel images of protein profiles of normal pancreas tissues (A) and pancreatic carcinoma (B). Proteins were separated by IEF as first dimension, using 24 cm tube gels pH 4–8 and linear gradient gel 11.5 to 19% as a second dimension. The protein spots were cut from the gel, trytically digested, and identified via MALDI-MS. Significantly expressed spots are posted in Table 1 along with their individual PD-Quest spot number assignment and other information.

Figure 3:

Immunohistochemistry validation of Annexin, ALDH1A1 and pancreatic lipase in pancreatic cancer, pancreatitis and normal tissues.