Identification of proteins implicated in the development of pancreatic cancer-associated diabetes mellitus by iTRAQ-based quantitative proteomics

Associations between Systemic Immune-Inflammation Index and Diabetes Mellitus Secondary to Pancreatic Ductal Adenocarcinoma

BACKGROUND

There is a high prevalence of diabetes mellitus (DM) in patients with pancreatic ductal adenocarcinoma (PDAC). An inflammatory response is considered as a potential mechanism involved in the process. The systemic immune-inflammation (SII) index is an integrated and novel inflammatory indicator developed in recent years. The purpose of this study was to determine the relationship between the SII and DM secondary to PDAC.

METHOD

Patients with a confirmed diagnosis of PDAC were analyzed in this cross-sectional study. Anthropometric measures, glucose-related data (including fasting glucose, 2 h OGTT, glycated hemoglobin, fasting insulin, and fasting c-peptide), tumor characteristics (tumor volumes, location and stages), and the periphery blood inflammatory index (white blood cell count, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and SII) were recorded. The inflammation index was analyzed for its association with glucose-related parameters. Multivariable logistic regression analysis was used to analyze the association between SII levels and DM secondary to PDAC.

RESULTS

Blood cell results showed that the white blood cell count, neutrophils, lymphocytes, monocytes, platelets, the neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio were higher in patients with diabetes. It was worth noting that SII significantly increased in patients with diabetes secondary to PDAC (4.41 vs. 3.19, p < 0.0001). Multivariable logistic regression analysis showed that SII (OR: 2.024, 95%CI: 1.297, 3.157, p = 0.002) and age (OR: 1.043, 95%CI: 1.01, 1.077, p = 0.011) were the risk factors for DM secondary to PDAC after adjusting for covariates. According to Spearmen correlation analysis, SII was positively correlated with fasting glucose (r = 0.345, p < 0.0001), 2 h OGTT (r = 0.383, p < 0.0001), HbA1c (r = 0.211, p = 0.005), fasting insulin (r = 0.435, p < 0.0001), fasting C-peptide (r = 0.420, p < 0.0001), and HOMA2-IR (r = 0.491, p < 0.0001).

CONCLUSIONS

In conclusion, SII is significantly increased among patients with DM secondary to PDAC and is associated with the DM in patients with PDAC (OR: 2.382, 95% CI: 1.157, 4.903, p = 0.019). Additionally, SII is significantly correlated with insulin resistance. We are the first to investigate the relationship between SII and diabetes secondary to PDAC and further confirm the role of an inflammatory response in this process. More studies need to be designed to clarify how inflammatory responses participate.

Pancreatic cancer cachexia: three dimensions of a complex syndrome

Cancer cachexia is a multifactorial syndrome that is characterised by a loss of skeletal muscle mass, is commonly associated with adipose tissue wasting and malaise, and responds poorly to therapeutic interventions. Although cachexia can affect patients who are severely ill with various malignant or non-malignant conditions, it is particularly common among patients with pancreatic cancer. Pancreatic cancer often leads to the development of cachexia through a combination of distinct factors, which, together, explain its high prevalence and clinical importance in this disease: systemic factors, including metabolic changes and pathogenic signals related to the tumour biology of pancreatic adenocarcinoma; factors resulting from the disruption of the digestive and endocrine functions of the pancreas; and factors related to the close anatomical and functional connection of the pancreas with the gut. In this review, we conceptualise the various insights into the mechanisms underlying pancreatic cancer cachexia according to these three dimensions to expose its particular complexity and the challenges that face clinicians in trying to devise therapeutic interventions.

LC-MS/MS and SWATH based serum metabolomics enables biomarker discovery in pancreatic cancer

BACKGROUND

Pancreatic cancer (PC) is the fourth leading cause of cancer death because of its subtle clinical symptoms in the early stage. To discover particular serum metabolites as potential biomarkers to differentiate pancreatic carcinoma from benign disease (BD) is on urgent demand.

METHOD

To comprehensively analyze serum metabolites obtained from 14 patients with PC, 10 patients with BD and 10 healthy individuals (normal control, NC), we separated the metabolites using both reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC). The data were acquired on a high-resolution quadrupole time-of-flight mass spectrometer operated in negative (ESI-) and positive (ESI+) ionization modes, respectively. Differential metabolites were selected by univariate (Student's t test) and multivariate (orthogonal partial least squares-discriminant analysis (OPLS-DA)) statistics. Sequential window acquisition of all theoretical spectra (SWATH) analysis was further utilized to validate the metabolites found in discovery stage. The receiver operator characteristics (ROC) curve analysis was performed to evaluate predictive clinical usefulness of 8 metabolites.

RESULTS

A total of 8 metabolites including taurocholic acid, glycochenodexycholic acid, glycocholic acid, L-glutamine, glutamic acid, L-phenylalanine, L-tryptophan, and L-arginine were identified and relatively quantified as differential metabolites for discriminating PC, BD and NC. The 8 metabolites and their combination discriminated PC from BD and NC with well-performed area under the curve (AUC) values, sensitivity and specificity.

CONCLUSION

Bile acids (especially taurocholic acid) performed to be potential biomarkers in PC diagnosis. Other amino acids (such as L-glutamine, glutamic acid, L-phenylalanine, L-tryptophan, and L-arginine) in serum samples from PC patients might provide a sensitive, blood-borne diagnostic signature for the presence of PC or its precursor lesions.

Galectin-3 and S100A9: Novel Diabetogenic Factors Mediating Pancreatic Cancer-Associated Diabetes

OBJECTIVE

Pancreatic cancer-associated diabetes (PCDM) is a paraneoplastic phenomenon accounting for 1% of new-onset diabetes. We aimed to identify the mediators of PCDM and evaluate their usefulness in distinguishing PCDM from type 2 diabetes.

RESEARCH DESIGN AND METHODS

Secreted proteins of MIA PaCa-2 cells were identified by proteomics, and those with ≥10-fold overexpression in transcriptome analysis were assessed by bioinformatics and glucose uptake assay to identify candidate factors. Expression of factors was compared between tumors with and without PCDM by immunohistochemistry. Serum levels were measured in a training set including PC with and without PCDM, type 2 diabetes, pancreatitis, other pancreatic/peripancreatic tumors, and control subjects (n = 50 each). Cutoff values for differentiation between PCDM and type 2 diabetes from the training set were validated in a test set (n = 41 each).

RESULTS

Galectin-3 and S100A9 were overexpressed in tumors with PCDM and dose-dependently suppressed insulin-stimulated glucose uptake in C2C12 myotubes. In the training set, serum galectin-3 and S100A9 levels were exclusively increased in patients with PCDM and distinguished PCDM from type 2 diabetes (area under the curve [AUC] galectin-3: 0.73 [95% CI 0.64-0.83]; S100A9: 0.79 [95% CI 0.70-0.87]). Similar results were observed in the test set (AUC galectin-3: 0.83 [95% CI 0.74-0.92]; S100A9: 0.77 [95% CI 0.67-0.87]), with sensitivity and specificity 72.1% and 86.1%, respectively, for galectin-3 and 69.8% and 58.1% for S100A9 in differentiating between PCDM and type 2 diabetes.

CONCLUSIONS

Galectin-3 and S100A9 are overexpressed in PCDM tumors and mediate insulin resistance. Galectin-3 and S100A9 distinguish PCDM from type 2 diabetes in subjects with new-onset diabetes.

Divergent proteomics response of Apostichopus japonicus suffering from skin ulceration syndrome and pathogen infection

Skin ulceration syndrome (SUS) of sea cucumber is a common and serious disease that affects the stable development of Apostichopus japonicus in the culture industry. The part of sea cucumber that suffers from major injury and is directly observed is the body wall, in which protein variations should be the most direct evidence of the disease. To understand the response mechanisms of A. japonicus in SUS progression, we investigated protein changes in the body wall of diseased A. japonicus induced by Vibrio splendidus and individuals with natural diseases by isobaric tags for relative and absolute quantification (iTRAQ). About 119 proteins were identified in the two iTRAQ groups. A comparison of the protein expression profiles among two SUS conditions revealed that the mode of action induced by V. splendidus (Vs-SUS) was completely different from those in individuals with natural disease (ND-SUS). Most of the differentially expressed proteins (DEPs) (33 in 37 DEPs) were significantly depressed in the Vs-SUS group. Only 13 proteins in 27 DEPs showed similar trend to those in the ND-SUS group. Many important proteins involved in major intercellular signaling pathways associated with SUS disease were identified based on the KEGG and GO database search. Many proteins were located in the mitochondria and mainly involved in the oxidative stress pathway. Glutathione metabolism pathway was associated with reactive oxygen (ROS) production in the ND-SUS group. In the Vs-group, most of the proteins were concentrated in the cytoplasm and were related to immunity and extracellular matrix stability. In the ND-SUS group, the activity of key enzymes (CAT, GPx) that eliminate mitochondrial ROS production and structural stable protein (HSP60, HSP10) decreased, whereas those of complement proteins (C3, C3-2) that promoted ROS production was upregulated. This finding supported that oxidative damage caused by ROS might be the main effector for SUS in the ND-SUS group. The challenge with V. splendidus led to the breakdown of the defense capability of sea cucumber and suppressed the expression of immune-related proteins, such as C-type lectin, caspase, STAT, and cystatin. The downregulation of TIMP led to MMP1 overexpression. Members of the MMP family could directly degrade the extracellular matrix, which may be the main reason for the cell matrix degradation and induced SUS disease in the Vs-SUS group. Hence, ROS and extracellular matrix degradation enzymes could play important roles in the formation of SUS in sea cucumber. Results provide insights into the complex molecular mechanism of SUS in sea cucumber.

Type-3c Diabetes Mellitus, Diabetes of Exocrine Pancreas - An Update

BACKGROUND

The incidence of diabetes is increasing steeply; the number of diabetics has doubled over the past three decades. Surprisingly, the knowledge of type 3c diabetes mellitus (T3cDM) is still unclear to the researchers, scientist and medical practitioners, leading towards erroneous diagnosis, which is sometimes misdiagnosed as type 1 diabetes mellitus (T1DM), or more frequently type 2 diabetes mellitus (T2DM). This review is aimed to outline recent information on the etiology, pathophysiology, diagnostic procedures, and therapeutic management of T3cDM patients.

METHODS

The literature related to T3cDM was thoroughly searched from the public domains and reviewed extensively to construct this article. Further, existing literature related to the other forms of diabetes is reviewed for projecting the differences among the different forms of diabetes. Detailed and updated information related to epidemiological evidence, risk factors, symptoms, diagnosis, pathogenesis and management is structured in this review.

RESULTS

T3cDM is often misdiagnosed as T2DM due to the insufficient knowledge differentiating between T2DM and T3cDM. The pathogenesis of T3cDM is explained which is often linked to the history of chronic pancreatitis, pancreatic cancer. Inflammation, and fibrosis in pancreatic tissue lead to damage both endocrine and exocrine functions, thus leading to insulin/glucagon insufficiency and pancreatic enzyme deficiency.

CONCLUSION

Future advancements should be accompanied by the establishment of a quick diagnostic tool through the understanding of potential biomarkers of the disease and newer treatments for better control of the diseased condition.

A Comprehensive Proteome Analysis of Peripheral Blood Mononuclear Cells (PBMCs) to Identify Candidate Biomarkers of Pancreatic Cancer

BACKGROUND/AIM

Pancreatic cancer (PC) is currently the fourth leading cause of cancer-related mortality worldwide. Peripheral blood mononuclear cells (PBMCs) is a subpopulation of accessible and functional immune cells. Comparative analysis of the proteome of PBMCs can help us elucidate the mechanism of disease and find potential biomarkers for diagnosis.

MATERIALS AND METHODS

PBMCs were collected from healthy individuals, patients with benign diseases, and pancreatic cancer. iTRAQ-2DLC-MS/MS and SWATH methodologies were applied to make a comparative proteomics analysis of PBMCs.

RESULTS

A total of 3,357 proteins with a false discovery rate (FDR) <1% were identified, of which 114 proteins were found dysregulated in the PC group. An extensive SWATH library was constructed which showed a potential application for large scale clinical sample analysis.

CONCLUSION

A PBMCs proteome with extensive protein representation was achieved, which will potentially allow the identification of novel biomarkers for PC.

A new panel of pancreatic cancer biomarkers discovered using a mass spectrometry-based pipeline

Background:

Pancreatic carcinoma (PC) is an aggressive malignancy that lacks strategies for early detection. This study aimed to develop a coherent, high-throughput and non-discriminatory pipeline for the novel clinical biomarker discovery of PC.

Methods:

We combined mass spectrometry (MS)-intensive methods such as isobaric tags for relative and absolute quantitation with two-dimensional liquid chromatography-tandem mass spectrometry (iTRAQ-2DLC-MS/MS), 1D-targeted LC-MS/MS, prime MRM (P-MRM) and stable isotope dilution-based MRM (SID-MRM) to analyse serum samples from healthy people (normal control, NC), patients with benign diseases (BD) and PC patients to identify novel biomarkers of PC.

Results:

On the basis of the newly developed pipeline, we identified >1000 proteins, verified 142 differentially expressed proteins and finally targeted four proteins for absolute quantitation in 100 serum samples. The novel biomarker panel of apolipoprotein E (APOE), inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3), apolipoprotein A-I (APOA1), apolipoprotein L1 (APOL1), combining with CA19-9, statistically-significantly improved the sensitivity (95%) and specificity (94.1%), outperforming CA19-9 alone, for the diagnosis of PC.

Conclusions:

We developed a highly efficient pipeline for biomarker discovery, verification and validation, with each step systematically informing the next. A panel of proteins that might be clinically relevant biomarkers for PC was found.

Chemical composition and the potential for proteomic transformation in cancer, hypoxia, and hyperosmotic stress

The changes of protein expression that are monitored in proteomic experiments are a type of biological transformation that also involves changes in chemical composition. Accompanying the myriad molecular-level interactions that underlie any proteomic transformation, there is an overall thermodynamic potential that is sensitive to microenvironmental conditions, including local oxidation and hydration potential. Here, up- and down-expressed proteins identified in 71 comparative proteomics studies were analyzed using the average oxidation state of carbon (Z_C) and water demand per residue (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}${\overline{n}}_{{\mathrm{H}}_{2}\mathrm{O}}$\end{document}n¯H2O), calculated using elemental abundances and stoichiometric reactions to form proteins from basis species. Experimental lowering of oxygen availability (hypoxia) or water activity (hyperosmotic stress) generally results in decreased Z_C or \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}${\overline{n}}_{{\mathrm{H}}_{2}\mathrm{O}}$\end{document}n¯H2O of up-expressed compared to down-expressed proteins. This correspondence of chemical composition with experimental conditions provides evidence for attraction of the proteomes to a low-energy state. An opposite compositional change, toward higher average oxidation or hydration state, is found for proteomic transformations in colorectal and pancreatic cancer, and in two experiments for adipose-derived stem cells. Calculations of chemical affinity were used to estimate the thermodynamic potentials for proteomic transformations as a function of fugacity of O₂ and activity of H₂O, which serve as scales of oxidation and hydration potential. Diagrams summarizing the relative potential for formation of up- and down-expressed proteins have predicted equipotential lines that cluster around particular values of oxygen fugacity and water activity for similar datasets. The changes in chemical composition of proteomes are likely linked with reactions among other cellular molecules. A redox balance calculation indicates that an increase in the lipid to protein ratio in cancer cells by 20% over hypoxic cells would generate a large enough electron sink for oxidation of the cancer proteomes. The datasets and computer code used here are made available in a new R package, canprot.

Proteomic strategies in the search for novel pancreatic cancer biomarkers and drug targets: recent advances and clinical impact

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers; despite a low incidence rate it is the fourth leading cause of cancer-related death in the world. Improvement of the diagnosis, prognosis and treatment remains the main focus of pancreatic cancer research. Rapid developments in proteomic technologies has improved our understanding of the pancreatic cancer proteome. Here, the authors summarise the recent proteomic strategies undertaken in the search for: novel biomarkers for early diagnosis, pancreatic cancer-specific proteins which may be used for novel targeted therapies and proteins which may be useful for monitoring disease progression post-therapy. Recent advances and findings discussed here provide great promise of having a significant clinical impact and improving the outcome of patients with this malignancy.

Type 3c (pancreatogenic) diabetes mellitus secondary to chronic pancreatitis and pancreatic cancer

Diabetes mellitus is a group of diseases defined by persistent hyperglycaemia. Type 2 diabetes, the most prevalent form, is characterised initially by impaired insulin sensitivity and subsequently by an inadequate compensatory insulin response. Diabetes can also develop as a direct consequence of other diseases, including diseases of the exocrine pancreas. Historically, diabetes due to diseases of the exocrine pancreas was described as pancreatogenic or pancreatogenous diabetes mellitus, but recent literature refers to it as type 3c diabetes. It is important to note that type 3c diabetes is not a single entity; it occurs because of a variety of exocrine pancreatic diseases with varying mechanisms of hyperglycaemia. The most commonly identified causes of type 3c diabetes are chronic pancreatitis, pancreatic ductal adenocarcinoma, haemochromatosis, cystic fibrosis, and previous pancreatic surgery. In this Review, we discuss the epidemiology, pathogenesis, and clinical relevance of type 3c diabetes secondary to chronic pancreatitis and pancreatic ductal adenocarcinoma, and highlight several important knowledge gaps.

Dissecting characteristics and dynamics of differentially expressed proteins during multistage carcinogenesis of human colorectal cancer

AIM: To discover novel biomarkers for early diagnosis, prognosis or treatment of human colorectal cancer.

METHODS: iTRAQ 2D LC-MS/MS analysis was used to identify differentially expressed proteins (DEPs) in the human colonic epithelial carcinogenic process using laser capture microdissection-purified colonic epithelial cells from normal colon, adenoma, carcinoma in situ and invasive carcinoma tissues.

RESULTS: A total of 326 DEPs were identified, and four DEPs (DMBT1, S100A9, Galectin-10, and S100A8) with progressive alteration in the carcinogenic process were further validated by immunohistochemistry. The DEPs were involved in multiple biological processes including cell cycle, cell adhesion, translation, mRNA processing, and protein synthesis. Some of the DEPs involved in cellular process such as “translation” and “mRNA splicing” were progressively up-regulated, while some DEPs involved in other processes such as “metabolism” and “cell response to stress” was progressively down-regulated. Other proteins with up- or down-regulation at certain stages of carcinogenesis may play various roles at different stages of the colorectal carcinogenic process.

CONCLUSION: These findings give insights into our understanding of the mechanisms of colorectal carcinogenesis and provide clues for further investigation of carcinogenesis and identification of biomarkers.

Characterization and comparison of proteomes of albino sea cucumber Apostichopus japonicus (Selenka) by iTRAQ analysis

Sea cucumber is a commercially important marine organism in China. Of the different colored varieties sold in China, albino sea cucumber has the greatest appeal among consumers. Identification of factors contributing to albinism in sea cucumber is therefore likely to provide a scientific basis for improving the cultivability of these strains. In this study, two-dimensional liquid chromatography-tandem mass spectrometry coupled with isobaric tags for relative and absolute quantification labeling was used for the first time to quantitatively define the proteome of sea cucumbers and reveal proteomic characteristics unique to albino sea cucumbers. A total of 549 proteins were identified and quantified in albino sea cucumber and the functional annotations of 485 proteins have been exhibited based on COG database. Compared with green sea cucumber, 12 proteins were identified as differentially expressed in the intestine and 16 proteins in the body wall of albino sea cucumber. Among them, 5 proteins were up-regulated in the intestine and 8 proteins were down-regulated in body wall. Gene ontology annotations of these differentially expressed proteins consisted mostly of 'biological process'. The large number of differentially expressed proteins identified here should be highly useful in further elucidating the mechanisms underlying albinism in sea cucumber.

Blood expression of matrix metalloproteinases 8 and 9 and of their inducers S100A8 and S100A9 supports diagnosis and prognosis of PDAC-associated diabetes mellitus

BACKGROUND

Based on the knowledge that matrix metalloproteinases (MMPs) and S100A8/A9 synergistically work in causing PDAC-associated type 2 diabetes mellitus (T2DM), we verified whether tissue and blood MMP8, MMP9, S100A8 and S100A9 expression might help in distinguishing PDAC among diabetics.

METHODS

Relative quantification of MMP8, MMP9, S100A8 and S100A9 mRNA was performed in tissues obtained from 8 PDAC, 4 chronic pancreatitis (ChrPa), 4 non-PDAC tumors and in PBMCs obtained from 30 controls, 43 T2DM, 41 ChrPa, 91 PDAC and 33 pancreatic-biliary tract tumors.

RESULTS

T2DM was observed in PDAC (66%), in pancreatic-biliary tract tumors (64%) and in ChrPa (70%). In diabetics, with or without PDAC, MMP9 tissue expression was increased (p<0.05). Both MMPs increased in PDAC and MMP9 increased also in pancreatic-biliary tract tumors PBMCs. In diabetics, MMP9 was independently associated with PDAC (p=0.025), but failed to enhance CA 19-9 discriminant efficacy. A highly reduced S100A9 expression, found in 7 PDAC, was significantly correlated with a reduced overall survival (p=0.015).

CONCLUSIONS

An increased expression of tissue and blood MMP9 reflects the presence of PDAC-associated diabetes mellitus. This finding fits with the hypothesized role of MMPs as part of the complex network linking cancer to diabetes.

Proteomic analyses of Urine Exosomes reveal New Biomarkers of Diabetes in Pregnancy

Objective

To evaluate 24 hour urine exosome protein content changes among pregnant US subjects with diabetes and obesity during early pregnancy.

Methods

The exosome proteome content from 24 hour urine samples of pregnant subjects with gestational diabetes mellitus (GDM, N=8) and pre-gestational Type 2 diabetes (PGD, N = 10) were compared with control samples (CTRL, N = 10) obtained at week 20 of pregnancy. Differences in exosome protein load between groups was identified by liquid chromatography/mass spectrometry, analyzed by linear regression in negative binomial distribution, visualized in MetaboAnalyst (version 3.0), and validated by western immunoblotting.

Results

At the 20^th week of pregnancy, we identified 646, 734 and 856 proteins in exosomes from 24 hour urine samples of patients from the CTRL, GDM and PGD groups, respectively. S100 calcium binding protein A9, damage associated molecular pattern (DAMP) signal, was found to be significantly increased in both GDM and PGD subjects. In GDM subjects the peptide counts for S100A9 protein independently correlated with maternal obesity and macrosomia of the newborn infants. Early to late pregnancy developmental changes in the GDM group were shown to utilize pathways and protein expression levels differently from those in PGD or CTRL groups.

Conclusions

Urinary exosome proteomic analysis non-invasively provides insights into maternal changes during diabetic pregnancy. Exosome biomarkers early in pregnancy can be potentially used to better understand pathophysiologic mechanisms of diabetes at a cellular level, and to distinguish between gestational and pre-gestational diabetes at the pathway level. This information can aid intervention efforts to improve pregnancy outcomes in women with diabetes.

Analysis of global gene expression profiles suggests a role of acute inflammation in type 3C diabetes mellitus caused by pancreatic ductal adenocarcinoma

AIMS/HYPOTHESIS

Pancreatic ductal adenocarcinoma (PDAC) can cause type 3C diabetes, known as PDAC-associated diabetes mellitus (PDAC-DM), but the mechanism is unknown. This study aimed to reveal the mechanism.

METHODS

PDAC lesions from patients with or without PDAC-DM (n = 4 in each group) were individually profiled for 23,512 mRNAs with microarrays. Bioinformatic analysis and in vivo and in vitro assays were then conducted.

RESULTS

We determined that 2,778 genes were differentially expressed; over-representation of ten genes was validated with quantitative RT-PCR. The analysis of gene ontology showed that the differentially expressed secretory genes were related mainly to inflammation. High levels of a marker of inflammation (C-reactive protein [CRP]) and an inflammatory mediator (TNF super-family member 13 [TNFSF13]) were found in the serum of patients with PDAC-DM. After surgical resection of PDAC lesions, CRP and TNFSF13 levels significantly decreased (p < 0.01). Furthermore, we found that the levels of TNFSF13 in PDAC lesions and TNFSF13 and CRP in serum were significantly correlated with the diabetic status of patients with PDAC-DM (p < 0.01). Assays in vivo showed that after exposure to an inhibitor of inflammation (celecoxib), the fasting blood glucose level in the mouse model of PDAC-DM dramatically decreased from 6.9 ± 0.1 to 5.6 ± 0.1 mmol/l in 2-4 days (p < 0.01).

CONCLUSIONS/INTERPRETATION

We found that acute inflammation was involved in the pathogenesis of PDAC-DM. We contend that acute inflammation is a potential target for the diagnosis and treatment of PDAC-DM.

Quantitative proteomics analysis by iTRAQ in human nuclear cataracts of different ages and normal lens nuclei

PURPOSE

The goal of this study was to quantitatively identify the differentially expressed proteins in nuclear cataracts of different ages and normal lens nuclei in humans.

EXPERIMENTAL DESIGN

Forty-eight human lens nucleus samples with hardness grades III, IV were obtained during cataract surgery by extracapsular cataract extraction. Seven normal transparent human lens nuclei were obtained from fresh normal cadaver eyes during corneal transplantation surgery. Lens nuclei were divided into seven groups according to age and optic axis: Group A (average age 80.8 ± 1.2 years), Group B (average age 57.0 ± 4.0 years), Group C average age 80.3 ± 4.5 years), Group D (average age 56.9 ± 4.2 years), Group E (average age 78.1 ± 2.5 years), Group F (average age 57.6 ± 3.3 years) and Group G (seven normal transparent human lenses from normal cadaver eyes, average age 34.7 ± 4.2 years). Water-soluble, water-insoluble, and water-insoluble-urea-soluble protein fractions were extracted from samples. The three-part protein fractions from the individual lenses were combined to form the total proteins of each sample. The proteomic profiles of each group were further analyzed using 8-plex iTRAQ labeling combined with 2D-LC-MS/MS. The data were analyzed with the ProteinPilot software for peptide matching, protein identification, and quantification. Differentially expressed proteins were validated by Western blotting.

RESULTS

We employed biological and technical replicates and selected the intersection of the two results, which included 80 proteins. Nine proteins were differentially expressed among the 80 proteins identified using proteomic techniques. In age-related nuclear cataracts (ARNC), the expression levels of fatty acid-binding protein and pterin-4-alpha-carbinolamine dehydratase were upregulated, whereas the levels of alpha-crystallin B chain (CRYAB), GSH synthetase, phakinin, gamma-crystallin C, phosphoglycerate kinase 1, betaine-homocysteine S-methyltransferase 1 (BHMT1), and spectrin beta chain were downregulated. These proteins may be associated with abnormal protein aggregation and oxidative stress. GSH synthetase and CRYAB expression levels in the nuclear cataract decreased with age. The mass spectrometric analysis results were consistent with the Western blot validation.

CONCLUSION AND CLINICAL RELEVANCE

The results indicate that CRYAB and GSH synthetase may be involved in ARNC pathogenesis. iTRAQ combined with 2D-LC-MS/MS provides new methods for future studies of pathological mechanisms and protective drug development for ARNC.