Protein Alterations Associated with Pancreatic Cancer and Chronic Pancreatitis Found in Human Plasma using Global Quantitative Proteomics Profiling

Abstract

Pancreatic cancer is a lethal disease that is difficult to diagnose at early stages when curable treatments are effective. Biomarkers that can improve current pancreatic cancer detection would have great value in improving patient management and survival rate. A large scale quantitative proteomics study was performed to search for the plasma protein alterations associated with pancreatic cancer. The enormous complexity of the plasma proteome and the vast dynamic range of protein concentration therein present major challenges for quantitative global profiling of plasma. To address these challenges, multi-dimensional fractionation at both protein and peptide levels was applied to enhance the depth of proteomics analysis. Employing stringent criteria, more than thirteen hundred proteins total were identified in plasma across 8-orders of magnitude in protein concentration. Differential proteins associated with pancreatic cancer were identified, and their relationship with the proteome of pancreatic tissue and pancreatic juice from our previous studies was discussed. A subgroup of differentially expressed proteins was selected for biomarker testing using an independent cohort of plasma and serum samples from well-diagnosed patients with pancreatic cancer, chronic pancreatitis and non-pancreatic disease controls. Using ELISA methodology, the performance of each of these protein candidates was benchmarked against CA19-9, the current gold standard for a pancreatic cancer blood test. A composite marker of TIMP1 and ICAM1 demonstrate significantly better performance than CA19-9 in distinguishing pancreatic cancer from the non-pancreatic disease controls and chronic pancreatitis controls. In addition, protein AZGP1 was identified as a biomarker candidate for chronic pancreatitis. The discovery and technical challenges associated with plasma-based quantitative proteomics are discussed and may benefit the development of plasma proteomics technology in general. The protein candidates identified in this study provide a biomarker candidate pool for future investigations.

Sequential Validation of Blood-Based Protein Biomarker Candidates for Early-Stage Pancreatic Cancer

“…Increased gene expression, and/or secretion of TIMP1, has been previously observed in PDAC and found to induce tumor cell proliferation (26,31,32). Although elevated circulating TIMP1 levels have been mostly associated with PDAC (13,14,(33)(34)(35)(36), increased levels have also been found in other epithelial tumor types (37)(38)(39). A role for LRG1 has been suggested in promoting angiogenesis through activation of the TGF-b pathway (40).…”

“…As a result, there is substantial ongoing effort to identify additional serological biomarkers that complement CA19-9 for the detection of early-stage PDAC. Markers investigated include proteins (9)(10)(11)(12)(13)(14), metabolites (15)(16)(17), autoantibodies (18,19), miRNAs (20)(21)(22), markers with aberrant glycosylation (CA19-9 and Tn antigens) (6,23,24), and exosomes (25). In view of the wide array of potential biomarkers, there is a need for systematic evaluation of candidates using CA19-9 as an anchor marker given its established performance.…”

Unraveling the sperm proteome and post-genomic pathways associated with sperm nuclear DNA fragmentation

“…These pools were then quantified in triplicate using the BCA assay mentioned above. A comprehensive shotgun analysis was then performed using the pooled samples in an experimental design created along the lines published by Cho et al [34] and Pan et al [35], and four technical replicates of each pool were used.…”

Combining in Vitro Diagnostics with in Vivo Imaging for Earlier Detection of Pancreatic Ductal Adenocarcinoma: Challenges and Solutions

“…Extensive separation at both protein and peptide level by using electrophoresis and multidimensional liquid chromatography is one way to enhance the identification of low abundant proteins in serum and/ or plasma. By using this approach, a large-scale quantitative proteomics study was performed to search for the plasma protein alterations associated with PDAC, and a biomarker panel of "tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) or intercellular adhesion molecule 1(ICAM-1)" was identified with 75% sensitivity and 95% specificity in distinguishing pancreatic cancer from the nonpancreatic disease control subjects and chronic pancreatitis control subjects (39). In another study in which a bead-based multiplex immunoassay was used, a biomarker panel of CA 19-9, ICAM-1, and osteoprotegerin could detect pancreatic cancer with 78% sensitivity and 94% specificity, and a biomarker panel of CA 19-9, carcinoembryonic antigen, and TIMP-1 demonstrated 71% sensitivity and 89% specificity in detecting PDAC (32).…”