Quantitative glycoproteomics analysis reveals changes in N-glycosylation level associated with pancreatic ductal adenocarcinoma.

Glycosylation plays an important role in epithelial cancers, including pancreatic ductal adenocarcinoma. However, little is known about the glycoproteome of the human pancreas or its alterations associated with pancreatic tumorigenesis. Using quantitative glycoproteomics approach, we investigated protein N-glycosylation in pancreatic tumor tissue in comparison with normal pancreas and chronic pancreatitis tissue. The study lead to the discovery of a roster of glycoproteins with aberrant N-glycosylation level associated with pancreatic cancer, including mucin-5AC (MUC5AC), carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), insulin-like growth factor binding protein (IGFBP3), and galectin-3-binding protein (LGALS3BP). Pathway analysis of cancer-associated aberrant glycoproteins revealed an emerging phenomenon that increased activity of N-glycosylation was implicated in several pancreatic cancer pathways, including TGF-ß, TNF, NF-kappa-B, and TFEB-related lysosomal changes. In addition, the study provided evidence that specific N-glycosylation sites within certain individual proteins can have significantly altered glycosylation occupancy in pancreatic cancer, reflecting the complexity of the molecular mechanisms underlying cancer-associated glycosylation events.

Zinc and iron dynamics in human islet amyloid polypeptide-induced diabetes mouse model.

Metal homeostasis is tightly regulated in cells and organisms, and its disturbance is frequently observed in some diseases such as neurodegenerative diseases and metabolic disorders. Previous studies suggest that zinc and iron are necessary for the normal functions of pancreatic ß cells. However, the distribution of elements in normal conditions and the pathophysiological significance of dysregulated elements in the islet in diabetic conditions have remained unclear. In this study, to investigate the dynamics of elements in the pancreatic islets of a diabetic mouse model expressing human islet amyloid polypeptide (hIAPP): hIAPP transgenic (hIAPP-Tg) mice, we performed imaging analysis of elements using synchrotron scanning X-ray fluorescence microscopy and quantitative analysis of elements using inductively coupled plasma mass spectrometry. We found that in the islets, zinc significantly decreased in the early stage of diabetes, while iron gradually decreased concurrently with the increase in blood glucose levels of hIAPP-Tg mice. Notably, when zinc and/or iron were decreased in the islets of hIAPP-Tg mice, dysregulation of glucose-stimulated mitochondrial respiration was observed. Our findings may contribute to clarifying the roles of zinc and iron in islet functions under pathophysiological diabetic conditions.

Multiplex targeted proteomic assay for biomarker detection in plasma: a pancreatic cancer biomarker case study.

Biomarkers are most frequently proteins that are measured in the blood. Their development largely relies on antibody creation to test the protein candidate performance in blood samples of diseased versus nondiseased patients. The creation of such antibody assays has been a bottleneck in biomarker progress due to the cost, extensive time, and effort required to complete the task. Targeted proteomics is an emerging technology that is playing an increasingly important role to facilitate disease biomarker development. In this study, we applied a SRM-based targeted proteomics platform to directly detect candidate biomarker proteins in plasma to evaluate their clinical utility for pancreatic cancer detection. The characterization of these protein candidates used a clinically well-characterized cohort that included plasma samples from patients with pancreatic cancer, chronic pancreatitis, and healthy age-matched controls. Three of the five candidate proteins, including gelsolin, lumican, and tissue inhibitor of metalloproteinase 1, demonstrated an AUC value greater than 0.75 in distinguishing pancreatic cancer from the controls. In addition, we provide an analysis of the reproducibility, accuracy, and robustness of the SRM-based proteomics platform. This information addresses important technical issues that could aid in the adoption of the targeted proteomics platform for practical clinical utility.

TRPV1 agonist monoacylglycerol increases UCP1 content in brown adipose tissue and suppresses accumulation of visceral fat in mice fed a high-fat and high-sucrose diet.

The administration of such a transient receptor potential vanilloid 1 (TRPV1) agonist as capsaicin, which is a pungent ingredient of red pepper, promotes energy metabolism and suppresses visceral fat accumulation. We have recently identified monoacylglycerols (MGs) having an unsaturated long-chain fatty acid as the novel TRPV1 agonist in foods. We investigated in this present study the effects of dietary MGs on uncoupling protein 1 (UCP1) expression in interscapular brown adipose tissue (IBAT) and on fat accumulation in mice fed with a high-fat, high-sucrose diet. The MG30 diet that substituted 30% of all lipids for MGs (a mixture of 1-oleoylglycerol, 1-linoleoylglycerol and 1-linolenoylglycerol) significantly increased the UCP1 content of IBAT and decreased the weight of epididymal white adipose tissue, and the serum glucose, total cholesterol and free fatty acid levels. The diet containing only 1-oleoylglycerol as MG also increased UCP1 expression in IBAT. MGs that activated TRPV1 also therefore induced the expression of UCP 1 and prevented visceral fat accumulation as well as capsaicin.

Spectral library-based glycopeptide analysis-detection of circulating galectin-3 binding protein in pancreatic cancer.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease characterized by its late diagnosis, poor prognosis and rapid development of drug resistance. Using the data-independent acquisition (DIA) technique, the authors applied a spectral library-based proteomic approach to analyze N-glycosylated peptides in human plasma, in the context of pancreatic cancer study. EXPERIMENTAL DESIGN: The authors extended the application of DIA to the quantification of N-glycosylated peptides enriched from plasma specimens from a clinically well-defined cohort that consists of patients with early stage PDAC, chronic pancreatitis and healthy subjects. RESULTS: The analytical platform was evaluated in light of its robustness for quantitative analysis of large-scale clinical specimens. The authors analysis indicated that the level of N-glycosylated peptides derived from galectin-3 binding proteins (LGALS3BP) were frequently elevated in plasma from PDAC patients, concurrent with the altered N-glycosylation of LGALS3BP observed in the tumor tissue. CONCLUSION AND CLINICAL RELEVANCE: The glycosylation form of LGALS3BP influences its function in the galectin network, which profoundly involves in cancer progression, immune response and drug resistance. As one of the major binding ligands of galectin network, discovery of site specific N-glycosylation changes of LGALS3BP in association of PDAC may provide useful clues to facilitate cancer detection or phenotype stratification.

Monitoring tumor cell proliferation by targeting DNA synthetic processes with thymidine and thymidine analogs.

UNLABELLED: The use of radiolabeled thymidine (TdR) and thymidine analogs as PET-based tracers of tumor growth rate is based on the assumption that measurement of uptake of these nucleosides, a function primarily of thymidine kinase-1 (TK(1)) activity, provides an accurate measure of active cell proliferation in tumors. The goal of this study was to test this hypothesis and determine how well these tracers track changes in proliferation of tumor cells. METHODS: TK(1) activity; S-phase fraction; and uptake of TdR, 3'-deoxy-3'-fluorothymidine (FLT), and 2'-fluoro-5-methyl-1-(beta-D-2-arabino-furanosyl) uracil (FMAU) were determined in plateau-phase and exponentially growing cultures of 3 human and 3 murine tumor cell lines. RESULTS: TK(1) activity and S-phase fraction increased in all cell lines as cells moved from plateau-phase conditions to exponential growth. Some cell lines had relatively large TK(1) activities and S-phase fractions under plateau-phase conditions, consistent with a loss of normal cell cycle checkpoint control in these cells. There were also 2 cell lines in which TK(1) activity changed little as cells moved from the plateau phase to exponential growth, suggesting that in these cell lines, de novo nucleotide synthesis pathways predominate over salvage pathways. Both TdR and FLT detected changes in TK(1) activity. The slope of the relationship between TdR uptake and TK(1) activity was nearly twice that for FLT and more than 40-fold that for FMAU. CONCLUSION: Although not all tumors show a strong TK(1) dependence of proliferation, in all cell lines for which proliferation is highly TK(1) dependent, phosphorylation of TdR or FLT accurately reflects changes in TK(1) enzyme activity.

Effect of p53 activation on cell growth, thymidine kinase-1 activity, and 3'-deoxy-3'fluorothymidine uptake.

The use of thymidine (TdR) and thymidine analogs such as 3'-deoxy-3'-fluorothymidine (FLT) as positron emission tomography (PET)-based tracers of tumor proliferation rate is based on the hypothesis that measurement of uptake of these nucleosides, a function primarily of thymidine kinase-1 (TK(1)) activity, provides an accurate measure of cell proliferation in tumors. Tumor growth is influenced by many factors including the oxygen concentration within tumors and whether tumor cells have been exposed to cytotoxic therapies. The p53 gene plays an important role in regulating growth under both of these conditions. The goal of this study was to investigate the influence of p53 activation on cell growth, TK(1) activity, and FLT uptake. To accomplish this, TK(1) activity, S phase fraction, and the uptake of FLT were determined in plateau-phase and exponentially growing cultures of an isogenic pair of human tumor cell lines in which p53 expression was normal or inactivated by human papilloma virus type 16 E6 expression. Ionizing radiation exposure was used to stimulate p53 activity and to induce alterations in cell cycle progression. We found that exposure of cells to ionizing radiation induced dose-dependent changes in cell cycle progression in both cell lines. The relationship between S phase percentage, TK(1) activity, and FLT uptake were essentially unchanged in the p53-normal cell line. In contrast, TK(1) activity and FLT uptake remained high in the p53-deficient variant even when S phase percentage was low due to a p53-dependent G2 arrest. We conclude that a functional p53 response is required to maintain the normal relationship between TK1 activity and S phase percentage following radiation exposure.

Ingestion of cinnamaldehyde, a TRPA1 agonist, reduces visceral fats in mice fed a high-fat and high-sucrose diet.

Cinnamaldehyde (CNA), a pungent compound in cinnamon or dried bark of cassia, is a TRPA1 agonist. The effect of 0.1-1.0% CNA on pair-fed mice with high fat and high sucrose (HFS) diet for 1 mo was investigated. The total food intake was similar in the mice fed control and CNA diets, but the body weight showed a tendency to be lower in CNA-fed mice than in control mice. By adding CNA at 0.1, 0.5, and 1.0% concentrations, the weight of the mesenteric adipose tissue decreased significantly, and there was a tendency foward lower perirenal and epididymal adipose tissue weights compared to the control. No differences were found in any blood component measured. UCP1 protein levels in the interscapular brown adipose tissue were higher in the 0.5 and 1.0% CNA groups than in the HSF group, as shown by Western blotting. Collectively, these data show that the addition of CNA diminishes visceral fat deposition in HFS diet-fed mice, in part by stimulating interscapular brown adipose tissue.

Large-scale quantitative glycoproteomics analysis of site-specific glycosylation occupancy.

Disease-associated aberrant glycosylation may be protein specific and glycosylation site specific. Quantitative assessment of glycosylation changes at a site-specific molecular level may represent one of the initial steps for systematically revealing the glycosylation abnormalities associated with a disease or biological state. Comparative quantitative profiling of glycoproteome to provide accurate quantification of site-specific glycosylation occupancy has been a challenging task, requiring a concerted approach drawing from a variety of techniques. In this report, we present a quantitative glycoproteomics method that allows global scale identification and comparative quantification of glycosylation site occupancy using mass spectrometry. We further demonstrated this approach by quantitatively characterizing the N-glycoproteome of human pancreas.

Proteomics portrait of archival lesions of chronic pancreatitis.

Chronic pancreatitis is a chronic inflammatory disorder of the pancreas. The etiology is multi-fold, but all lead to progressive scarring and loss of pancreatic function. Early diagnosis is difficult; and the understanding of the molecular events that underlie this progressive disease is limited. In this study, we investigated differential proteins associated with mild and severe chronic pancreatitis in comparison with normal pancreas and pancreatic cancer. Paraffin-embedded formalin-fixed tissues from five well-characterized specimens each of normal pancreas (NL), mild chronic pancreatitis (MCP), severe chronic pancreatitis (SCP) and pancreatic ductal adenocarcinoma (PDAC) were subjected to proteomic analysis using a "label-free" comparative approach. Our results show that the numbers of differential proteins increase substantially with the disease severity, from mild to severe chronic pancreatitis, while the number of dysregulated proteins is highest in pancreatic adenocarcinoma. Important functional groups and biological processes associated with chronic pancreatitis and cancer include acinar cell secretory proteins, pancreatic fibrosis/stellate cell activation, glycoproteins, and inflammatory proteins. Three differential proteins were selected for verification by immunohistochemistry, including collagen 14A1, lumican and versican. Further canonical pathway analysis revealed that acute phase response signal, prothrombin activation pathway, and pancreatic fibrosis/pancreatic stellate cell activation pathway were the most significant pathways involved in chronic pancreatitis, while pathways relating to metabolism were the most significant pathways in pancreatic adenocarcinoma. Our study reveals a group of differentially expressed proteins and the related pathways that may shed light on the pathogenesis of chronic pancreatitis and the common molecular events associated with chronic pancreatitis and pancreatic adenocarcinoma.

Proteins That Underlie Neoplastic Progression of Ulcerative Colitis.

Patients with ulcerative colitis (UC) have an increased risk for developing colorectal cancer. Because UC tumorigenesis is associated with genomic field defects that can extend throughout the entire colon, including the non-dysplastic mucosa; we hypothesized that the same field defect will include abnormally expressed proteins. Here we applied proteomics to study the protein expression of UC neoplastic progression. The protein profiles of colonic epithelium were compared from 1) UC patients without dysplasia (non-progressors); 2) none-dysplastic colonic tissue from UC patient with high-grade dysplasia or cancer (progressors); 3) high-grade dysplastic tissue from UC progressors and 4) normal colon. We identified protein differential expression associated with UC neoplastic progression. Proteins relating to mitochondria, oxidative activity, calcium-binding proteins were some of interesting classes of these proteins. Network analysis discovered that Sp1 and c-myc proteins may play roles in UC early and late stages of neoplastic progression, respectively. Two over-expressed proteins in the non-dysplastic tissue of UC progressors, CPS1 and S100P, were further confirmed by IHC analysis. Our study provides insight into the molecular events associated with UC neoplastic progression, which could be exploited for the development of protein biomarkers in fields of non-dysplastic mucosa that identify a patient's risk for UC dysplasia.