Plasma proteomics of pancreatic cancer patients by multi-dimensional liquid chromatography and two-dimensional difference gel electrophoresis (2D-DIGE): Up-regulation of leucine-rich alpha-2-glycoprotein in pancreatic cancer

Abstract

We investigated the aberrant expression of plasma proteins in patients with pancreatic cancer. High-abundance plasma proteins (albumin, transferrin, haptoglobin, alpha-1-antitrypsin, IgG and IgA) were depleted by use of an immuno-affinity column, and low-abundance ones were separated into five fractions by anion-exchange chromatography. The fractionated plasma proteins were subjected to 2D-DIGE with highly sensitive fluorescent dyes. The quantitative protein expression profiles obtained by 2D-DIGE were compared between two plasma protein mixtures: one from five non-cancer bearing healthy donors and the other from five patients with pancreatic cancer. Among 1200 protein spots, we found that 33 protein spots were differently expressed between the two mixtures; 27 of these were up-regulated and six were down-regulated in cancer. Mass spectrometry and database searching allowed the identification of the proteins corresponding to the gel spots. Up-regulation of leucine-rich alpha-2-glycoprotein (LRG), which has not previously been implicated in pancreatic cancer, was observed. Western blotting with an anti-LRG antibody validated the up-regulation of LRG in an independent series of plasma samples from healthy controls, patients with chronic pancreatitis, and patients with pancreatic cancer. Our results demonstrate the application of a combination of multi-dimensional liquid chromatography with 2D-DIGE for plasma proteomics and suggest the clinical utility of LRG plasma level measurement.

Integrated Proteomic Profiling of Cell Line Conditioned Media and Pancreatic Juice for the Identification of Pancreatic Cancer Biomarkers

“…Increased GDF15 mRNA and protein levels have been shown previously in pancreatic cancer tissue in comparison to adjacent normal controls (66) and evaluation of this protein in serum has also shown it to have diagnostic potential (67). Similarly, neutrophil gelatinase-associated lipocalin (LCN2) (71), matrix metalloproteinase 7 (MMP7) (68), complement component 3 (C3) (63,70), and leucine-rich alpha-2-glycoprotein (LRG1) (97) have been reported to be elevated in serum of pancreatic cancer patients, whereas mesothelin (MSLN) (98), tissue-type plasminogen activator (PLAT) (99), C-X-C motif chemokine 5 (CXCL5) (100) and other proteins highlighted in Table III have been shown to be up-regulated in pancreatic cancer or pancreatic neoplasia at the level of tissue and/or mRNA. In addition, other proteins, such as Lysyl oxidase-like 2 (LOXL2), have been associated with pancreatic cancer pathology and tumorigenicity.…”

Proteomics study of serum exosomes in Kawasaki disease patients with coronary artery aneurysms

“…Previous research has shown that LRG1 is involved in important pathological and biological processes, such as cell adhesion, signal transduction, and protein-protein interactions [21]. Recently, LRG1 was found to be elevated in the serum of patients with lung cancer, liver cancer, and pancreatic adenocarcinoma [22,23]. In the present study, it was found that LRG1 was up-regulated in CAA serum exosomes, suggesting that it may be involved in the development of CAA, and that the immune response to infection might contribute to the formation of CAA in KD.…”

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

“…A role for LRG1 has been suggested in promoting angiogenesis through activation of the TGF-b pathway (40). Apart from PDAC, increased LRG1 plasma levels have also been found in other cancer types (41)(42)(43)(44)(45).…”