Alteration of protein glycosylation in human hepatic stellate cells activated with transforming growth factor-β1. J Proteomics. 2012;75:4114-4123. [PMID: 22659384 DOI: 10.1016/j.jprot.2012.05.040]

Alterations in mitochondrial protein glycosylation in myocardial ischaemia reperfusion injury

The alterations in mitochondrial protein glycosylation in myocardial ischaemia reperfusion (I/R) injury are still unclear. Therefore, based on a lectin microarray and liquid chromatograph-mass spectrometer/mass spectrometer (LC‒MS/MS) technology combined with a bioinformatics analysis, we studied the changes in mitochondrial protein glycosylation during I/R injury. This study revealed significant differences in mitochondrial glycoprotein during I/R injury. Compared with the sham operation group, the model group, which underwent ischaemia for 30 min, showed a high expression of glycan structures recognized by lectins, such as WFA, PTL-I, LTL, GSL-I, SBA and SNA, and a low expression of glycan structures recognized by ConA, VVA and RCA120. The model group, which underwent ischaemia for 45 min, showed a high expression of glycan structures recognized by LTL and SNA and a low expression of glycan structures recognized by ECA. Further analysis showed that the Siaα2-6Gal/N-acetylgalactosamine (GalNAc) structures recognized by SNA were significantly increased. In total, 91 differential proteins were identified by LC‒MS/MS, and 8 hub genes were screened by Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and protein interaction analyses. Compared with the Gene Expression Omnibus (GEO) database genes, two differential genes, Pros1 and Vtn, were obtained. Pros1 is a key regulator of the inflammatory response and vascular injury response. The Vtn gene variant is associated with the risk of myocardial infarction. This study is expected to provide a new method for the treatment of I/R injury and could provide new ideas for the postoperative prognosis of patients.

Unraveling the pathophysiologic role of galectin-3 in chronically injured liver

Galectin-3 (Gal-3) previously referred to as S-type lectins, is a soluble protein that specifically binds to β-galactoside carbohydrates with high specificity. Gal-3 plays a pivotal role in a variety of pathophysiological processes such as cell proliferation, inflammation, differentiation, angiogenesis, transformation and apoptosis, pre-mRNA splicing, metabolic syndromes, fibrosis, and host defense. The role of Gal-3 has also been implicated in liver diseases. Gal-3 is activated upon a hepatotoxic insult to the liver and its level has been shown to be upregulated in fatty liver diseases, inflammation, nonalcoholic steatohepatitis, fibrosis, cholangitis, cirrhosis, and hepatocellular carcinoma (HCC). Gal-3 directly interacts with the NOD-like receptor family, pyrin domain containing 3, and activates the inflammasome in macrophages of the liver. In the chronically injured liver, Gal-3 secreted by injured hepatocytes and immune cells, activates hepatic stellate cells (HSCs) in a paracrine fashion to acquire a myofibroblast like collagen-producing phenotype. Activated HSCs in the fibrotic liver secrete Gal-3 which acts via autocrine signaling to exacerbate extracellular matrix synthesis and fibrogenesis. In the stromal microenvironment, Gal-3 activates cancer cell proliferation, migration, invasiveness, and metastasis. Clinically, increased serum levels and Gal-3 expression were observed in the liver tissue of nonalcoholic steatohepatitis, fibrotic/cirrhotic, and HCC patients. The pathological role of Gal-3 has been experimentally and clinically reported in the progression of chronic liver disease. Therefore, this review discusses the pathological role of Gal-3 in the progression of chronic liver diseases.

Integrating transcriptomics, proteomics, glycomics and glycoproteomics to characterize paclitaxel resistance in breast cancer cells

Chemoresistance is a major factor driving breast cancer (BC) relapse and the high rates of cancer-related deaths. Aberrant levels of glycans are closely correlated with chemoresistance. The essential functions of glycans in chemoresistance is not systematically studied. In this study, an integrated strategy with a combination of transcriptomics, proteomics, glycomics and glycoproteomics was applied to explore the dysregulation of glycogenes, glycan structures and glycoproteins in chemoresistance of breast cancer cells. In paclitaxel (PTX) resistant MCF7 cells, 19 differentially expressed N-glycan-related proteins were identified, of which MGAT4A was the most significantly down-regulated, consistent with decrease in MGAT4A expression at mRNA level in PTX treated BC cells. Glycomic analysis consistently revealed suppressed levels of multi-antennary branching structures using MALDI-TOF/TOF-MS and lectin microarray. Several target glycoproteins bearing suppressed levels of multi-antennary branching structures were identified, and ERK signaling pathway was strongly suppressed in PTX resistant MCF7 cells. Our findings demonstrated the aberrant levels of multi-antennary branching structures and their target glycoproteins on PTX resistance. Systematically integrative multi-omic analysis is expected to facilitate the discovery of the aberrant glycosyltransferases, N-glycosylation and glycoproteins in tumor progression and chemoresistance. SIGNIFICANCE: An integrated strategy with a combination of transcriptomics, proteomics, glycomics and glycoproteomics is crucial to understand the association between glycans and chemoresistance in BC. In this multi-omic analysis, we identified unique glycan-related protein, glycan and glycoprotein signatures defining PTX chemoresistance in BC. This study might provide valuable information to understand molecular mechanisms underlying chemoresistance in BC.

The Power of Plasticity-Metabolic Regulation of Hepatic Stellate Cells

Hepatic stellate cells (HSCs) are resident non-parenchymal liver pericytes whose plasticity enables them to regulate a remarkable range of physiologic and pathologic responses. To support their functions in health and disease, HSCs engage pathways regulating carbohydrate, mitochondrial, lipid, and retinoid homeostasis. In chronic liver injury, HSCs drive hepatic fibrosis and are implicated in inflammation and cancer. To do so, the cells activate, or transdifferentiate, from a quiescent state into proliferative, motile myofibroblasts that secrete extracellular matrix, which demands rapid adaptation to meet a heightened energy need. Adaptations include reprogramming of central carbon metabolism, enhanced mitochondrial number and activity, endoplasmic reticulum stress, and liberation of free fatty acids through autophagy-dependent hydrolysis of retinyl esters that are stored in cytoplasmic droplets. As an archetype for pericytes in other tissues, recognition of the HSC's metabolic drivers and vulnerabilities offer the potential to target these pathways therapeutically to enhance parenchymal growth and modulate repair.

Up-regulation of FUT8 inhibits TGF-β1-induced activation of hepatic stellate cells during liver fibrogenesis

Liver fibrosis is a continuous wound healing response caused by chronic liver injury, and the activation of hepatic stellate cells (HSCs) is considered as the main event for it. Core fucosylation catalyzed by FUT8 refers to adding the fucosyl moiety to the innermost GlcNAc residue of N-linked oligosaccharides and is involved in many biological processes such as cell differentiation, migration, and signaling transduction. Aberrant core fucosylation is associated with a variety of diseases including cardiovascular disease, tumors and neuroinflammation, but much less is understood in liver fibrosis. Herein, we reported FUT8 mRNA level was increased in patients with liver fibrosis from GEO database and positively correlated with fibrosis progression. FUT8 expression and the core fucosylation were also elevated in TAA-induced mouse liver fibrosis model, and were mainly distributed in the fibrous septum of mouse liver. TGF-β1, as the most pro-fibrogenic cytokine, could promote the expression of FUT8 and total core fucosylation levels in HSCs in vitro. However, up-regulation of FUT8 in turn inhibited TGF-β1-induced trans-differentiation, migration and pro-fibrogenic signaling pathways in HSCs. In conclusion, our results suggest that the up-regulation of FUT8 inhibits TGF-β1-induced HSC activation in a negative feedback loop, and provide potential new therapeutic strategy for liver fibrosis by targeting FUT8.

Protein Glycopatterns in Bronchoalveolar Lavage Fluid as Novel Potential Biomarkers for Diagnosis of Lung Cancer

Lung cancer is one of the most prevalent and life-threatening neoplasias worldwide due to the deficiency of ideal diagnostic biomarkers. Although aberrant glycosylation has been observed in human serum and tissue, little is known about the alterations in bronchoalveolar lavage fluid (BALF) that are extremely associated with lung cancer. In this study, our aim was to systematically investigate and assess the alterations of protein glycopatterns in BALF and possibility as biomarkers for diagnosis of lung cancer. Here, lectin microarrays and blotting analysis were utilized to detect the differential expression of BALF glycoproteins from patients with 80 adenocarcinomas (ADC), 77 squamous carcinomas (SCC), 51 small cell lung cancer (SCLC), and 73 benign pulmonary diseases (BPD). These 281 specimens were then randomly divided into a training cohort and validation cohort for constructing and verifying the diagnostic models based on the glycopattern abundances. Moreover, an independent test was performed with 120 newly collected BALF samples enrolled in the double-blind cohort to further assess the clinical application potential of the diagnostic models. According to the results, there were 15 (e.g., PHA-E, EEL, and BPL) and 14 lectins (e.g., PTL-II, LCA, and SJA) that individually showed significant variations in different types and stages of lung cancer compared to BPD. Notably, the diagnostic models achieved better discriminate power in the validation cohort and exhibited high accuracies of 0.917, 0.864, 0.712, 0.671, and 0.781 in the double-blind cohort for the diagnosis of lung cancer, early stage lung cancer, ADC, SCC, and SCLC, respectively. Taken together, the present study revealed that the abnormally altered protein glycopatterns in BALF are expected to be novel potential biomarkers for the identification and early diagnosis of lung cancer, which will contribute to explain the mechanism of the development of lung cancer from the perspective of glycobiology.

Mapping glycan-mediated galectin-3 interactions by live cell proximity labeling

Galectin-3 is a glycan-binding protein (GBP) that binds β-galactoside glycan structures to orchestrate a variety of important biological events, including the activation of hepatic stellate cells and regulation of immune responses. While the requisite glycan epitopes needed to bind galectin-3 have long been elucidated, the cellular glycoproteins that bear these glycan signatures remain unknown. Given the importance of the three-dimensional (3D) arrangement of glycans in dictating GBP interactions, strategies that allow the identification of GBP receptors in live cells, where the native glycan presentation and glycoprotein expression are preserved, have significant advantages over static and artificial systems. Here we describe the integration of a proximity labeling method and quantitative mass spectrometry to map the glycan and glycoprotein interactors for galectin-3 in live human hepatic stellate cells and peripheral blood mononuclear cells. Understanding the identity of the glycoproteins and defining the structures of the glycans will empower efforts to design and develop selective therapeutics to mitigate galectin-3-mediated biological events.

Remarkable Homeostasis of Protein Sialylation in Skeletal Muscles of Hibernating Daurian Ground Squirrels (Spermophilus dauricus)

As the most common post-translational protein modification, glycosylation is intimately linked to muscle atrophy. This study aimed to investigate the performance of protein glycosylation in the soleus muscle (SOL) in Daurian ground squirrels (Spermophilus dauricus) and to determine the potential role of protein glycosylation in the mechanism underlying disuse muscle atrophy prevention. The results showed that (1) seven glycan structures comprising sialic acid α2-3 galactose (SAα2-3Gal) were altered during hibernation; (2) alterations in the SAα2-3Gal structure during hibernation were based on changes in the expression levels of beta-galactoside alpha-2 and 3-sialyltransferases; and (3) α2-3–linked sialylated modifications of heat shock cognate 70 and pyruvate kinase and expression of 14-3-3 epsilon protein were oscillatorily changed during hibernation. Our findings indicate that the skeletal muscles of hibernating Daurian ground squirrels maintain protein sialylation homeostasis by restoring sialylation modification during periodic interbout arousal, which might protect the skeletal muscles against disuse atrophy.

Lectin microarrays for glycoproteomics: an overview of their use and potential

Introduction: Glycoproteomics is an important subdiscipline of proteomics, focusing on the role of protein glycosylation in various biological processes. Protein glycosylation is the enzymatic addition of sugars or oligosaccharides to proteins. Altered glycosylation often occurs in the early stages of disease development, for example, certain tumor-associated glycans have been shown to be expressed in precursor lesions of different types of cancer, making them powerful early diagnostic markers. Lectin microarrays have become a powerful tool for both the study of glycosylation and the diagnosis of various diseases including cancer.Areas covered: This review will discuss the most useful features of lectin microarrays, such as their technological advances, their capability for parallel/high-throughput analysis for the important glycopatterns of glycoprotein, and an overview of their use for glycosylation analysis of various complex protein samples, as well as their diagnostic potential in various diseases.Expert opinion: Lectin microarrays have proved to be useful in studying multiple lectin-glycan interactions in a single experiment and, with the advances made in the field, hold a promise of enabling glycopatterns of diseases in a fast and efficient manner. Lectin microarrays will become increasingly powerful early diagnostic tool for a variety of conditions.

MyoD1 suppresses cell migration and invasion by inhibiting FUT4 transcription in human gastric cancer cells

Myogenic differentiation 1 (MyoD1) is a transcription factor that promotes expression of muscle-specific genes. MyoD1 is expressed at significantly lower levels in gastric cancer (GC) tissues and cells, and it induces apoptosis in GC cells. However, functions for MyoD1 in GC cell migration and gene expression have not been documented. We show that knockdown of MyoD1 promoted migration and invasion of GC cells, whereas MyoD1 overexpression suppressed migration and invasion. We performed chromatin immunoprecipitation (ChIP)-sequencing to identify MyoD1 target genes in MKN-45 cells. The 2-kb upstream regions (Up2k) of the transcription start sites of 57 genes were probably bound by MyoD1. Six of these genes function in signaling pathways such as synthesis of glycosphingolipid biosynthesis—lacto and neolacto series. MyoD1 inhibited transcription of fucosyltransferase IV (FUT4) by binding directly to the FUT4 F3; this finding was validated by ChIP-quantitative PCR and a luciferase reporter assay. Ulex europaeus agglutinin I, which binds Fucα1-2Galβ1-4GlcNAc, and Lewis antigens showed decreased binding to the plasma membrane of cells that overexpressed MyoD1. Knockdown of FUT4 mimicked MyoD1 overexpression by suppressing GC cell migration and invasion; this result implied that MyoD1 suppressed cell migration and invasion via inhibiting the FUT4/matrix metallopeptidase signaling pathway. In summary, this study demonstrated that MyoD1 suppresses migration and invasion of GC cells by directly binding to the F3 region in the FUT4 Up2k and inhibiting FUT4/type II Lewis antigen expression.

Metabolic Signature of Hepatic Fibrosis: From Individual Pathways to Systems Biology

Hepatic fibrosis is a major cause of morbidity and mortality worldwide, as it ultimately leads to cirrhosis, which is estimated to affect up to 2% of the global population. Hepatic fibrosis is confirmed by liver biopsy, and the erroneous nature of this technique necessitates the search for noninvasive alternatives. However, current biomarker algorithms for hepatic fibrosis have many limitations. Given that the liver is the largest organ and a major metabolic hub in the body, probing the metabolic signature of hepatic fibrosis holds promise for the discovery of new markers and therapeutic targets. Regarding individual metabolic pathways, accumulating evidence shows that hepatic fibrosis leads to alterations in carbohydrate metabolism, as aerobic glycolysis is aggravated in activated hepatic stellate cells (HSCs) and the whole fibrotic liver; in amino acid metabolism, as Fischer’s ratio (branched-chain amino acids/aromatic amino acids) decreases in patients with hepatic fibrosis; and in lipid metabolism, as HSCs lose vitamin A-containing lipid droplets during transdifferentiation, and cirrhotic patients have decreased serum lipids. The current review also summarizes recent findings of metabolic alterations relevant to hepatic fibrosis based on systems biology approaches, including transcriptomics, proteomics, and metabolomics in vitro, in animal models and in humans.

High expression levels of influenza virus receptors in airway of the HBV-transgenic mice

In the human population, influenza A viruses are associated with acute respiratory illness and are responsible for millions of deaths annually. Avian and human influenza viruses typically have a different α2-3- and α2-6-linked sialic acid (SA) binding preference. Only a few amino acid changes in the haemagglutinin on the surface of avian influenza viruses (AIV) can cause a switch from avian to human receptor specificity, and the individuals with pathognostic chronic diseases might be more susceptible to AIV due to the decreased expression level of terminal α2-3-linked SA in their saliva. Here, using lectin and virus histochemical staining, we observed the higher expression levels of α2-3/6-linked SA influenza virus receptors in the airway of HBV-transgenic mice compared with that of control mice due to the significant decrease in control mice during ageing, which imply that this is also a risk factor for individuals with pathognostic chronic diseases susceptible to influenza viruses. Our findings will help understand the impact on influenza virus pathogenesis and transmission.

Regular alteration of protein glycosylation in skeletal muscles of hibernating Daurian ground squirrels (Spermophilus dauricus)

Glycosylation is one of the most common post-translational protein modifications and is closely associated with muscle atrophy. This study aims to investigate the changes in glycan profiles in the fast-twitch extensor digitorum longus (EDL) muscles of Daurian ground squirrels (Spermophilus dauricus) during hibernation as well as the correlation between protein glycosylation and muscle atrophy prevention in hibernating animals. The results showed that there was no significant change in the muscle-to-body mass ratio, muscle fiber cross-sectional area (CSA), fiber distribution and ultrastructures in the EDL muscles of ground squirrels during hibernation. Alterations of six glycans comprising sialic acid α2-3 galactose (Sia2-3Gal) and Fucα1-2Galβ1-4Glc(NAc) in the EDL muscles were observed. In addition, the observed downregulation of sialyltransferase (ST3Gals) mRNA levels and upregulation of fucosyltransferase (FUT1 and FUT2) mRNA levels during hibernation and the subsequent restoration to normal levels during periodic interbout arousal were consistent with the changes in sialic acid and fucose modifications. Our results indicate that changes in ST3Gals and FUTs in the EDL muscles of Daurian ground squirrels during hibernation can alter sialylation and fucosylation of muscle glycoproteins, which may protect the skeletal muscles of hibernating Daurian ground squirrels from disuse atrophy.

Analysis of Glycosphingolipid Glycans by Lectin Microarrays

Glycosphingolipids (GSLs) are ubiquitous glycoconjugates of cell membranes. Identification of unknown GSL-glycan structures is still a major challenge. To address this challenge, we developed a novel strategy for analysis of GSL-glycans from cultured cells based on a lectin microarray that can directly detect and reveal glycopatterns of GSL extracts without the need for glycan release. There were six steps to perform the analysis of GSL-glycans: (i) extraction of GSLs from cell pellets, (ii) quantification of GSL-glycans using orcinol-sulfuric acid reaction, (iii) preparation of lyso-GSLs by using sphingolipid ceramide N-deacylase, (iv) fluorescence labeling of lyso-GSLs, (v) detection by a lectin microarray, (vi) data acquisition and analysis. Simultaneously, a supplementary verification analysis for GSL-glycans was performed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Optimized experimental conditions, which consisted of the blocking buffer, incubation buffer, and appropriate GSL concentration, were investigated by analyzing the glycopatterns of a standard ganglioside (GM1a) via lectin microarray. The analysis of GSL-glycans from human hepatocarcinoma cell lines (MHCC97L, MHCC97H, and HCCLM3) showed that there were 27 lectins (e.g., WFA, MAL-II, and LTL) to give significantly different signals compared with a normal human liver cell line (HL-7702), indicating up- and/or down-regulations of corresponding glycopatterns such as α1-2 fucosylation and α2-3 sialylation, and changes of certain glycostructures such as Galβ1-3GalNAcβ1-4(NeuAcα2-3)Galβ1-4Glc:Cer and GalNAcα1-3(Fucα1-2)Galβ1-3GlcNAcβ1-3Galβ1-4Glc:Cer. The lectin microarray analysis of lyso-GSLs labeled by fluorescence has proven to be credible, which can provide the glycopatterns and detailed linkage information on GSL-glycans.

Glycopatterns and Glycoproteins Changes in MCN and SCN: A Prospective Cohort Study

Background. Advances in imaging improve the detection of malignant pancreatic cystic including mucinous cystic neoplasm (MCN), intraductal papillary mucinous neoplasm (IPMN), and mucinous cystic adenocarcinoma (MCA), but the distinction between benign and malignant lesions remains a problem. In an effort to establish glycopatterns as potential biomarkers for differential diagnosis between MCN and SCN, we systematically investigated the alterations of glycopatterns in cystic fluids for both SCN and MCN. Methods. Among the 75 patients enrolled, 37 were diagnosed as MCN and 38 as SCN based on histology. Lectin microarray analysis was performed on each sample, and the fluorescence intensity was used to obtain the fold-change. Then, mixed cyst fluids of MCN group and SCN group were cross bonded with magnetic particles coupled by Lectin STL and WGA, respectively. Hydrophilic interaction liquid chromatography (HILIC) enrichment was performed, liquid chromatography (LC)/mass spectrometry (MS) analysis and bioinformatical analysis was conducted to find the differential glycoproteins between MCNs and SCNs. Results. Through analysis of lectin microarray between MCNs and SCNs, stronger lectin signal patterns were assigned to Lectin WFA, DBA, STL, WGA, and BPL; and weaker signal patterns were assigned to Lectin PTL-I, Con A, ACA, and MAL-I. The glycoproteins were enriched by STL or WGA-coupled magnetic particles. Furthermore, the 10 identified correspondding genes were found to be significantly elevated in the mucinous cystadenoma: CLU, A2M, FGA, FGB, FGG, PLG, SERPINA1, SERPING1, C5, C8A, and C9. Bioinformatics analysis revealed that the above genes may activate the KEGG pathway: immune complement system. Conclusion. This study shows changes in glycopatterns and glycoproteins are associated with MCNs and SCNs.

Stage-associated differences in the serum N- and O-glycan profiles of patients with non-small cell lung cancer

Background

Lung cancer is the leading cause of cancer death in China and around the world. Early detection is key to improving the survival rate of non-small cell lung cancer (NSCLC). Alteration in glycosylation has been observed in cancers, and glycans can be a source for the development of new biomarkers for NSCLC.

Methods

In this glycan biomarker discovery study, we measured serum N- and O-glycan profiles in NSCLC patients with different stages and healthy controls by performing lectin microarray analysis. The alterations of serum glycopatterns were compared between NSCLC patients and controls, and the stage-related changes in serum glycosylation were evaluated.

Results

There were 18 lectins (e.g., AAL, Jacalin, GSL-I and DBA) to give significantly alterations of serum glycopatterns in lung adenocarcinoma compared with control group. Meanwhile, 16 lectins (e.g., Jacalin, HHL, and PHA-E+L) exhibited significantly alterations of serum glycopatterns in squamous cell carcinoma (SCC) compared with control group. Importantly, most of the lectins showing altered signals exhibited significantly increased or decreased NFIs in patients with early stage adenocarcinoma and SCC.

Conclusions

The serum glycan profiles were significantly different between NSCLC and healthy control, and most of the glycosylation changes had occurred at early stage. Further evaluation is needed to examine the diagnostic value of the glycan markers identified in this study.

Lectin microarray and mass spectrometric analysis of hepatitis C proteins reveals N-linked glycosylation

We used lectin microarray and mass spectrometric analysis to identify the N-linked glycosylation patterns of hepatitis C virus (HCV) particles. HCV J6/JFH-1 chimeric cell culture (HCVcc) in the culture supernatant was concentrated and purified by ultrafiltration and sucrose gradient ultracentrifugation. Twelve fractions were collected from the top and analyzed for viral infectivity and HCV RNA content after sucrose gradient separation. HCV RNA and proteins were separated by ultracentrifugation in a continuous 10% to 60% sucrose gradient to purify viral particles based on their sedimentation velocities. HCVcc particles were found mainly in fractions 6 to 8, as determined by quantitative polymerase chain reaction (qPCR) analysis for HCV RNA and ELISA of the HCV core protein. The N-glycans on HCV proteins were analyzed by lectin microarray and mass spectrometry. We identified that 32 of 37 lectins displayed the positive binding signals and 16 types of N-glycoforms of which the major HCV glycoforms were high mannose-type N-linked oligosaccharides, hybrid N-glycans, and fucosylated N-glycans. Our study provided new detailed information regarding the majority of the glycan-protein profile, complementing to previous findings of glycan-HCV protein interactions.

The enrichment and characterization of ginger-derived glycoprotein using magnetic particles

Ginger-derived glycoproteins are a widely distributed group of biological macromolecules with multiple functions. To date, the structure of ginger-derived glycoproteins has not been clarified with regard to their complexity, their sequence diversity and their uneven micro-distribution. In this study, a lectin microarray was used to evaluate 37 types of lectins and determine the optimal lectins that can conjugate with glycoproteins based on the fluorescence intensity. Subsequently, the lectins were immobilized on magnetic beads, coupled with glycoproteins to enrich ginger-derived glycoproteins, and evaluated using SDS-PAGE. Our results showed that five lectins (e.g. VVA, ConA, STL, LEL, and LCA) were selected by the lectin microarray and that VVA showed the highest fluorescence intensity. In addition, it is indicated that the structure of the carbohydrate chains might contain GlaNAc, mannose, GlcNAc, and LacNAc.

Bisecting N-Acetylglucosamine Structures Inhibit Hypoxia-Induced Epithelial-Mesenchymal Transition in Breast Cancer Cells

The epithelial-mesenchymal transition (EMT) process plays a key role in many biological processes, including tissue fibrosis, metastatic diseases, and cancer progression. EMT can be induced by certain factors, notably hypoxia, in the tumor microenvironment. Aberrant levels of certain N-glycans is associated with cancer progression. We used an integrated strategy (mass spectrometry in combination with lectin microarray analysis) to elucidate aberrant glycosylation in a hypoxia-induced EMT model using breast cancer cell lines MCF7 and MDA-MB-231. The model showed reduced levels of bisecting GlcNAc structures, and downregulated expression of the corresponding glycosyltransferase MGAT3. MGAT3 overexpression in MCF7 suppressed cell migration, proliferation, colony formation, expression of EMT markers, and AKT signaling pathway, whereas MGAT3 knockdown (shRNA silencing) had opposite effects. Our findings clearly demonstrate the functional role (and effects of dysregulation) of bisecting GlcNAc structures in hypoxia-induced EMT, and provide a useful basis for further detailed studies of physiological functions of these structures in breast cancer.

Identification of aberrantly expressed glycans in gastric cancer by integrated lectin microarray and mass spectrometric analyses

Cancer progression is usually associated with alterations of glycan expression patterns. Little is known regarding global glycomics in gastric cancer, the most common type of epithelial cancer. We integrated lectin microarray and mass spectrometry (MS) methods to profile glycan expression in three gastric cancer cell lines (SGC-7901, HGC-27, and MGC-803) and one normal gastric epithelial cell line (GES-1). Significantly altered glycans were confirmed by lectin staining and MALDI-TOF/TOF-MS. The three cancer cell lines showed increased levels of core-fucosylated N-glycans, GalNAcα-Ser/Thr (Tn antigen), and Sia2-6Galβ1-4GlcNAc N-glycans, but reduced levels of biantennary N-glycans, Galβ1-3GalNAcα-Ser/Thr (T antigen), and (GlcNAc)_n N-glycans. Lectin histochemistry was used to validate aberrant expression of four representative glycans (core-fucosylation, Sia2-6Galβ1-4GlcNAc, biantennary N-glycans, T antigen, recognized respectively by lectins LCA, SNA, PHA-E+L, and ACA) in clinical gastric cancer samples. Lower binding capacity for ACA was correlated with significantly poorer patient prognosis. Our findings indicate for the first time that glycans recognized by LCA, ACA, and PHA-E+L are aberrantly expressed in gastric cancer, and suggest that ACA is a potential prognostic factor for gastric cancer.

c-Jun-dependent β3GnT8 promotes tumorigenesis and metastasis of hepatocellular carcinoma by inducing CD147 glycosylation and altering N-glycan patterns

β3GnT8, a key polylactosamine synthase, plays a vital role in progression of various types of human cancer. The role of β3GnT8 in hepatocellular carcinoma (HCC) and the underlying mechanisms, however, remain largely unknown. In this study, we found that β3GnT8 and polylactosamine were highly expressed in HCC tissues compared with those in adjacent paracancer tissues. Overexpression of β3GnT8 promoted while knockdown of β3GnT8 inhibited HCC cell invasion and migration in vitro. Importantly, enhanced tumorigenesis was observed in nude mice inoculated with β3GnT8-overexpressing HCC cells, suggesting that β3GnT8 is important for HCC development in vitro and in vivo. Mechanistically, β3GnT8 modulated the N-glycosylation patterns of CD147 and altered the polylactosamine structures in HCC cells by physically interacting with CD147. In addition, our data showed the c-Jun could directly bind to the promoter of β3GnT8 gene and regulate β3GnT8 expression. β3GnT8 regulated HCC cell invasion and migration in a C-Jun-dependent manner. Collectively, our study identified β3GnT8 as a novel regulator for HCC invasion and tumorigenesis. Targeting β3GnT8 may be a potential therapeutic strategy against HCC.

Alterations of protein glycosylation in embryonic stem cells during adipogenesis

The understanding of adipose tissue development is crucial for the treatment of obesity-related diseases. Adipogenesis has been extensively investigated at the gene and protein levels in recent years. However, the alterations in protein glycosylation during this process remains unknown, particularly that of parthenogenetic embryonic stem cells (pESCs), a type of ESCs with low immunogenicity and no ethical concerns regarding their use. Protein glycosylation markedly affects cell growth and development, cell-to-cell communication, tumour growth and metastasis. In the present study, the adipogenic potentials of J1 ESCs and pESCs were first compared and the results demonstrated that pESCs had lower adipogenic potential compared with J1 ESCs. Lectin microarray was then used to screen the alteration of protein glycosylation during adipogenesis. The results revealed that protein modification of GlcNAc and α-1-2-fucosylation increased, whereas α-1-6‑fucosylation, α-2-6-sialylation and α-1-6-mannosylation decreased in J1 ESCs and pESCs during this process. In addition, α-1-3-mannosylation decreased only in pESCs. Lectin histochemistry and quantitative polymerase chain reaction of glycosyltransferase confirmed the results obtained by lectin microarray. Therefore, protein glycosylation of ESCs was significantly altered during adipogenesis, indicating that protein glycosylation analysis is not only helpful for studying the mechanism of adipogenesis, but may also be used as a marker to monitor adipogenic development.

Lectin BS-I inhibits cell migration and invasion via AKT/GSK-3β/β-catenin pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is most common malignant cancer worldwide; however, the mortality rate of HCC remains high due to the invasion and metastasis of HCC. Thus, exploring novel treatments to prevent the invasion of HCC is needed for improving clinical outcome of this fatal disease. In this study, we identified lectin from Bandeiraea simplicifolia seeds (BS‐I) binds to metastasis‐associated HCC cell surface glycans by a lectin microarray and inhibits HCC cell migration and invasion through downregulating the matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9) and urokinase‐type plasminogen activator (uPA) production. These effects of BS‐I were mediated by inhibiting the activation of AKT/GSK‐3β/β‐catenin pathway and depended on specificity of lectin BS‐I binding to GalNAc. GSK3β inhibitors rescued BS‐I‐mediated inhibition of migration and invasion of HCC cell. Further, we identified that lectin BS‐I interacts with sGrp78, affects membrane localization of sGrp78 and attenuates the binding of sGrp78 and p85 to inhibit the activation of AKT/GSK‐3β/β‐catenin pathway. Overexpression of Grp78 or P85 rescues BS‐I‐mediated inhibition of migration and invasion of HCC cell. These findings demonstrated for the first time that BS‐I can act as a novel potential drug to prevent the invasion of HCC.

Conditioned Medium from Malignant Breast Cancer Cells Induces an EMT-Like Phenotype and an Altered N-Glycan Profile in Normal Epithelial MCF10A Cells

Epithelial-mesenchymal transition (EMT) is a key process in cancer development and progression. Communication (crosstalk) between cancer cells and normal (nonmalignant) cells may facilitate cancer progression. Conditioned medium (CM) obtained from cultured cancer cells contains secreted factors capable of affecting phenotypes and the behaviors of normal cells. In this study, a culture of normal breast epithelial MCF10A cells with CM from malignant breast cancer cells (termed 231-CM and 453-CM) resulted in an alteration of morphology. CM-treated MCF10A, in comparison with control cells, showed a reduced expression of the epithelial marker E-cadherin, increased expression of the mesenchymal markers fibronectin, vimentin, N-cadherin, and TWIST1, meanwhile cell proliferation and migration were enhanced while cell apoptosis was decreased. N-glycan profiles of 231-CM-treated and control MCF10A cells were compared by MALDI-TOF/TOF-MS (Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry) and a lectin microarray analysis. The treated cells showed lower levels of high-mannose-type N-glycan structures, and higher levels of complex-type and hybrid-type structures. Altered N-glycan profiles were also detected in 453-CM-treated and non-treated MCF10A cells by MALDI-TOF/TOF-MS, and we found that the expression of five fucosylated N-glycan structures (m/z 1406.663, 1590.471, 1668.782, 2421.141, and 2988.342) and one high-mannose structure m/z 1743.722 have the same pattern as 231-CM-treated MCF10A cells. Our findings, taken together, show that CM derived from breast cancer cells induced an EMT-like process in normal epithelial cells and altered their N-glycan profile.

Serum glycopattern and Maackia amurensis lectin-II binding glycoproteins in autism spectrum disorder

The pathophysiology of autistic spectrum disorder (ASD) is not fully understood and there are no diagnostic or predictive biomarkers. Glycosylation modified as many as 70% of all human proteins can sensitively reflect various pathological changes. However, little is known about the alterations of glycosylation and glycoproteins in ASD. In this study, serum glycopattern and the maackia amurensis lectin-II binding glycoproteins (MBGs) in 65 children with ASD and 65 age-matched typically developing (TD) children were compared by using lectin microarrays and lectin-magnetic particle conjugate-assisted LC-MS/MS analyses. Expression of Siaα2-3 Gal/GalNAc was significantly increased in pooled (fold change = 3.33, p < 0.001) and individual (p = 0.009) serum samples from ASD versus TD children. A total of 194 and 217 MGBs were identified from TD and ASD sera respectively, of which 74 proteins were specially identified or up-regulated in ASD. Bioinformatic analysis revealed abnormal complement cascade and aberrant regulation of response-to-stimulus that might be novel makers or markers for ASD. Moreover, increase of APOD α2-3 sialoglycosylation could sensitively and specifically distinguish ASD samples from TD samples (AUC is 0.88). In conclusion, alteration of MBGs expression and their sialoglycosylation may serve as potential biomarkers for diagnosis of ASD, and provide useful information for investigations into the pathogenesis of ASD.

Serum Glycopatterns as Novel Potential Biomarkers for Diagnosis of Acute-on-Chronic Hepatitis B Liver Failure

Acute-on-chronic hepatitis B liver failure (ACHBLF) is an increasingly recognized distinct disease entity encompassing an acute deterioration of liver function in patients with cirrhosis, so little is known about the alterations of protein glycopatterns in serum with its development. We aimed to identify the alterations of serum glycopatterns in ACHBLF and probe the possibility of them as novel potential biomarkers for diagnosis of ACHBLF. As a result, there were 18 lectins (e.g., WFA, GSL-II, and PNA) to give significantly alterations of serum glycopatterns in ACHBLF compared with healthy controls (HC) (all p ≤ 0.0386). Meanwhile, among these lectins, there were 12 lectins (e.g., WFA, GAL-II, and EEL) also exhibited significantly alterations of serum glycopatterns in ACHBLF compared with HBV-infected chronic hepatitis (cHB) (all p ≤ 0.0252). The receiver-operating characteristic (ROC) curve analysis indicated there were 5 lectins (PHA-E + L, BS-I, ECA, ACA, and BPL) had the greatest discriminatory power for distinguishing ACHBLF and HC or cHB, respectively (all p ≤ 0.00136). We provided a new basic insight into serum glycopatterns in ACHBLF and investigated the correlation of alterations in serum glycopatterns as novel potential biomarkers for diagnosis of ACHBLF.

Comparison of the glycopattern alterations of mitochondrial proteins in cerebral cortex between rat Alzheimer's disease and the cerebral ischemia model

Alzheimer’s disease (AD) and ischemic brain injury are two major neurodegenerative diseases. Mitochondrial dysfunction commonly occurs in AD and ischemic brain injury. Currently, little attention has been paid to the glycans on mitochondrial glycoproteins, which may play vital roles during the process of mitochondrial dysfunction. The aim of this study was to illustrate and compare the glycopattern alterations of mitochondrial glycoproteins extracted from the cerebral cortex of the rat models of these two diseases using High-throughput lectin microarrays. The results shown that the number of lectins with significant differences compared to normal brains was nine for the rat sporadic Alzheimer’s disease (SAD) model and eighteen for the rat middle cerebral artery occlusion (MCAO) model. Interestingly, five lectins showed opposite expression patterns between the SAD and MCAO rat models. We conclude that glycopattern alterations of mitochondrial glycoproteins in the cerebral cortex may provide vital information to help understand mitochondrial dysfunction in AD and ischemic brain injury. In addition, glycans recognized by diverse lectins with opposite expression patterns between these two diseases hints at the different pathomechanisms of mitochondrial dysfunction in AD and ischemic brain injury.

Identification and localization of xylose-binding proteins as potential biomarkers for liver fibrosis/cirrhosis

In our recent study, we found that the expression levels of total xylose-binding proteins (XBPs) were up-regulated significantly in activated hepatic stellate cells (HSCs); however, the denomination, distribution, and function of the XBPs were uncharted. Herein, 70 XBPs from activated HSCs and 64 XBPs from quiescent HSCs were isolated, identified and annotated. A total of 30 XBPs were up-regulated (all fold change ≥ 1.5, p ≤ 0.05) and 14 XBPs were down-regulated (all fold change ≤ 0.67, p ≤ 0.05) in the activated HSCs. The XBPs were localized at the cytoplasm and cytoplasmic membrane in HSCs and cirrhotic liver tissues by cy/histochemistry. The XBPs (i.e. PDIA6 and CFL2) responsible for the regulation of protein binding were up-regulated and those responsible for the regulation of catalytic activity (i.e. TUBB and MX1) were up-regulated in the activated HSCs. 2 candidates (i.e. PDIA6 and APOA1) were then selected for further verification in the sera of patients with HBV-induced chronic hepatitis/cirrhosis using western blotting and serum microarrays. PDIA6 showed a higher discrimination (Area Under Curves, AUCs = 0.8985, p < 0.0001) relative to APOA1 (AUCs = 0.8738, p < 0.0001) in the sera of patients as biomarker candidate. In conclusion, the precision alteration of the XBPs associated with pathological changes in HSCs during liver fibrosis/cirrhosis may provide pivotal information needed to discover potential glycan-binding protein-related biomarkers for diagnosis of liver fibrosis/cirrhosis and for development of new anti-fibrotic strategies.

MicroRNA Expression Profiling in CCl₄-Induced Liver Fibrosis of Mus musculus

Liver fibrosis is a major pathological feature of chronic liver diseases, including liver cancer. MicroRNAs (miRNAs), small noncoding RNAs, regulate gene expression posttranscriptionally and play important roles in various kinds of diseases; however, miRNA-associated hepatic fibrogenesis and its acting mechanisms are poorly investigated. Therefore, we performed an miRNA microarray in the fibrotic livers of Mus musculus treated with carbon-tetrachloride (CCl₄) and analyzed the biological functions engaged by the target genes of differentially-expressed miRNAs through gene ontology (GO) and in-depth pathway enrichment analysis. Herein, we found that four miRNAs were upregulated and four miRNAs were downregulated more than two-fold in CCl₄-treated livers compared to a control liver. Eight miRNAs were predicted to target a total of 4079 genes. GO analysis revealed that those target genes were located in various cellular compartments, including cytoplasm, nucleolus and cell surface, and they were involved in protein-protein or protein-DNA bindings, which influence the signal transductions and gene transcription. Furthermore, pathway enrichment analysis demonstrated that the 72 subspecialized signaling pathways were associated with CCl₄-induced liver fibrosis and were mostly classified into metabolic function-related pathways. These results suggest that CCl₄ induces liver fibrosis by disrupting the metabolic pathways. In conclusion, we presented several miRNAs and their biological processes that might be important in the progression of liver fibrosis; these findings help increase the understanding of liver fibrogenesis and provide novel ideas for further studies of the role of miRNAs in liver fibrosis.

Unique glycosignature for intervertebral disc and articular cartilage cells and tissues in immaturity and maturity

In this study, on/off markers for intervertebral disc (IVD) and articular cartilage (AC) cells (chondrocytes) and distinct glycoprofiles of cell and tissue-types were identified from immaturity to maturity. Three and eleven month-old ovine IVD and AC tissues were histochemically profiled with a panel of lectins and antibodies. Relationships between tissue and cell types were analysed by hierarchical clustering. Chondroitin sulfate (CS) composition of annulus fibrosus (AF), nucleus pulposus (NP) and AC tissues was determined by HPLC analysis. Clear on/off cell type markers were identified, which enabled the discrimination of chondrocytes, AF and NP cells. AF and NP cells were distinguishable using MAA, SNA-I, SBA and WFA lectins, which bound to both NP cells and chondrocytes but not AF cells. Chondrocytes were distinguished from NP and AF cells with a specific binding of LTA and PNA lectins to chondrocytes. Each tissue showed a unique CS composition with a distinct switch in sulfation pattern in AF and NP tissues upon disc maturity while cartilage maintained the same sulfation pattern over time. In conclusion, distinct glycoprofiles for cell and tissue-types across age groups were identified in addition to altered CS composition and sulfation patterns for tissue types upon maturity.

Alteration of liver glycopatterns during cirrhosis and tumor progression induced by HBV

The incidence of hepatocellular carcinoma (HCC) is closely correlated with hepatitis B virus (HBV)-induced liver cirrhosis. Structural changes in the glycans of serum and tissue proteins are reliable indicators of liver damage. However, little is known about the alteration of liver glycopatterns during cirrhosis and tumor progression induced by HBV infection. This study compared the differential expression of liver glycopatterns in 7 sets of normal pericarcinomatous tissues (PCTs), cirrhotic, and tumor tissues from patients with liver cirrhosis and HCC induced by HBV using lectin microarrays. Fluorescence-based lectin histochemistry and lectin blotting were further utilized to validate and assess the expression and distribution of certain glycans in 9 sets of corresponding liver tissue sections. Eight lectins (e.g., Jacalin and AAL) revealed significant difference in cirrhotic tissues versus PCTs. Eleven lectins (e.g., EEL and SJA) showed significant alteration during cirrhotic and tumor progression. The expression of Galα1-3(Fucα1-2)Gal (EEL) and fucosyltransferase 1 was mainly increasing in the cytoplasm of hepatocytes during PCTs-cirrhotic-tumor tissues progression, while the expression of T antigen (ACA and PNA) was decreased sharply in cytoplasm of tumor hepatocytes. Understanding the precision alteration of liver glycopatterns related to the development of hepatitis, cirrhosis, and tumor induced by HBV infection may help elucidate the molecular mechanisms underlying the progression of chronic liver diseases and develop new antineoplastic therapeutic strategies.

Characterization and sub-cellular localization of GalNAc-binding proteins isolated from human hepatic stellate cells

Although the expression levels of total GalNAc-binding proteins (GNBPs) were up-regulated significantly in human hepatic stellate cells (HSCs) activated with transforming growth factor-β1(TGF-β1), yet little is known about the precise types, distribution and sub-cellular localization of the GNBPs in HSCs. Here, 264 GNBPs from the activated HSCs and 257 GNBPs from the quiescent HSCs were identified and annotated. A total of 46 GNBPs were estimated to be significantly up-regulated and 40 GNBPs were estimated to be significantly down-regulated in the activated HSCs. For example, the GNBPs (i.e. BTF3, COX17, and ATP5A1) responsible for the regulation of protein binding were up-regulated, and those (i.e. FAM114A1, ENO3, and TKT) responsible for the regulation of protein binding were down-regulated in the activated HSCs. The motifs of the isolated GNBPs showed that Proline residue had the maximum preference in consensus sequences. The western blotting showed the expression levels of COX17, and PRMT1 were significantly up-regulated, while, the expression level of CLIC1(B5) was down-regulated in the activated HSCs and liver cirrhosis tissues. Moreover, the GNBPs were sub-localized in the Golgi apparatus of HSCs. In conclusion, the precision alteration of the GNBPs referred to pathological changes in liver fibrosis/cirrhosis may provide useful information to find new molecular mechanism of HSC activation and discover the biomarkers for diagnosis of liver fibrosis/cirrhosis as well as development of new anti-fibrotic strategies.

Altered glycomics in liver disease

Chronic liver diseases are a serious health problem worldwide. The biosynthesis of proteins takes place in the liver, and protein glycosylation is the most common form of post-translational modification of proteins, with as many as 70% of all human proteins estimated to contain one or more glycan chains. Protein glycosylation is the enzymatic addition of sugars or oligosaccharides to proteins, which increases the diversity of the proteome to a level unmatched by any other post-translational modifications because of the various aspects of modification, including glycosidic bond, glycan composition, glycan structure, and glycan length. Changes in the glycan structures of proteins are an indication for liver damage, which plays an important role in the pathogenesis and progression of various liver diseases. The aim of this paper is to give an overview of the altered protein glycosylation in different etiologies of hepatitis, liver fibrosis/cirrhosis, hepatocellular carcinoma, alcoholic and fatty liver diseases based on the analysis of serum and saliva using the glycomics technology.

Alteration and localization of glycan-binding proteins in human hepatic stellate cells during liver fibrosis

Glycan-binding proteins (GBPs) play an important role in cell adhesion, bacterial/viral infection, and cellular signaling pathways. However, little is known about the precision alteration of GBPs referred to pathological changes in hepatic stellate cells (HSCs) during liver fibrosis. Here, the carbohydrate microarrays were used to probe the alteration of GBPs in the activated HSCs and quiescent HSCs. As a result, 12 carbohydrates (e.g. Gal, GalNAc, and Man-9Glycan) showed increased signal, while seven carbohydrates (e.g. NeuAc, Lac, and GlcNAc-O-Ser) showed decreased signal in activated HSCs. Three carbohydrates (Gal, GalNAc, and NeuAc) were selected and subsequently used to validate the results of the carbohydrate microarrays as well as assess the distribution and localization of their binding proteins in HSCs and liver tissues by cy/histochemistry; the results showed that GBPs mainly distributed in the cytoplasma membrane and perinuclear region of cytoplasm. The immunocytochemistry was further used to verify some GBPs really exist in Golgi apparatus of the cells. The precision alteration and localization of GBPs referred to pathological changes in HSCs may provide pivotal information to help understand the biological functions of glycans how to exert through their recognition by a wide variety of GBPs. This study could lead to the development of new anti-fibrotic strategies.

Toxic proteins in plants

Plants have evolved to synthesize a variety of noxious compounds to cope with unfavorable circumstances, among which a large group of toxic proteins that play a critical role in plant defense against predators and microbes. Up to now, a wide range of harmful proteins have been discovered in different plants, including lectins, ribosome-inactivating proteins, protease inhibitors, ureases, arcelins, antimicrobial peptides and pore-forming toxins. To fulfill their role in plant defense, these proteins exhibit various degrees of toxicity towards animals, insects, bacteria or fungi. Numerous studies have been carried out to investigate the toxic effects and mode of action of these plant proteins in order to explore their possible applications. Indeed, because of their biological activities, toxic plant proteins are also considered as potentially useful tools in crop protection and in biomedical applications, such as cancer treatment. Genes encoding toxic plant proteins have been introduced into crop genomes using genetic engineering technology in order to increase the plant's resistance against pathogens and diseases. Despite the availability of ample information on toxic plant proteins, very few publications have attempted to summarize the research progress made during the last decades. This review focuses on the diversity of toxic plant proteins in view of their toxicity as well as their mode of action. Furthermore, an outlook towards the biological role(s) of these proteins and their potential applications is discussed.

Avian influenza virus infection risk in humans with chronic diseases

Saliva proteins may protect older people from influenza, however, it is often noted that hospitalizations and deaths after an influenza infection mainly occur in the elderly population living with chronic diseases, such as diabetes and cancer. Our objective was to investigate the expression level of the terminal α2-3- and α2-6-linked sialic acids in human saliva from type 2 diabetes mellitus (T2DM), liver disease and gastric cancer (GC) patients and assess the binding activity of these linked sialic acids against influenza A viruses (IAV). We observed that the expression level of the terminal α2-3-linked sialic acids of elderly individuals with T2DM and liver disease were down-regulated significantly, and the terminal α2-6 linked sialic acids were up-regulated slightly or had no significant alteration. However, in the saliva of patients with GC, neither sialic acid was significantly altered. These findings may reveal that elderly individuals with chronic diseases, such as diabetes and liver disease, might be more susceptible to the avian influenza virus due to the decreased expression of terminal α2-3-linked sialic acids in their saliva.

Quantitative glycome analysis of N-glycan patterns in bladder cancer vs normal bladder cells using an integrated strategy

Diagnosis of bladder cancer, one of the most common types of human cancer, at an early (nonmuscle-invasive) stage is the best way to reduce the mortality rate. Tumor malignancy in general is closely associated with alterations of glycan expression. Glycosylation status, particularly global glycomes, in bladder cancer has not been well studied. We integrated lectin microarray and mass spectrometry (MS) methods to quantitatively analyze and compare glycan expression in four bladder cancer cell lines (KK47, YTS1, J82, T24) and one normal bladder mucosa cell line (HCV29). Glycopattern alterations were analyzed using lectin microarray analysis and confirmed by lectin staining and lectin blotting. Associations of glycopatterns with diverging stages were evaluated by lectin histochemistry on tissue microarrays. N-Glycans were derivatized by amidation of sialylated glycans with acetohydrazide and reductive amination with the stable isotope tags [(12)C6]- and [(13)C6]-aniline, and were quantitatively analyzed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). N-Glycan biosynthesis-associated proteins were quantitatively analyzed by a stable isotope labeling by amino acids in cell culture (SILAC) proteomics method, which revealed significant differences in expression of 13 glycosyltransferases and 4 glycosidases. Our findings indicate that sialyl Lewis X (sLe(x)), terminal GalNAc and Gal, and high mannose-type N-glycans were more highly expressed in bladder cancer cells and tissues than in normal cells. Bladder cancer cells showed high expression of core-fucosylated N-glycans but low expression of terminally fucosylated N-glycans. Each of these glycome changes may be directly related to bladder cancer progression.

Alteration of N-glycans and expression of their related glycogenes in the epithelial-mesenchymal transition of HCV29 bladder epithelial cells

The epithelial-mesenchymal transition (EMT) is an essential step in the proliferation and metastasis of solid tumor cells, and glycosylation plays a crucial role in the EMT process. Certain aberrant glycans have been reported as biomarkers during bladder cancer progression, but global variation of N-glycans in this type of cancer has not been previously studied. We examined the profiles of N-glycan and glycogene expression in transforming growth factor-beta (TGFβ)-induced EMT using non-malignant bladder transitional epithelium HCV29 cells. These expression profiles were analyzed by mass spectrometry, lectin microarray analysis, and GlycoV4 oligonucleotide microarray analysis, and confirmed by lectin histochemistry and real-time RT-PCR. The expression of 5 N-glycan-related genes were notably altered in TGFβ-induced EMT. In particular, reduced expression of glycogene man2a1, which encodes α-mannosidase 2, contributed to the decreased proportions of bi-, tri- and tetra-antennary complex N-glycans, and increased expression of hybrid-type N-glycans. Decreased expression of fuca1 gene, which encodes Type 1 α-L-fucosidase, contributed to increased expression of fucosylated N-glycans in TGFβ-induced EMT. Taken together, these findings clearly demonstrate the involvement of aberrant N-glycan synthesis in EMT in these cells. Integrated glycomic techniques as described here will facilitate discovery of glycan markers and development of novel diagnostic and therapeutic approaches to bladder cancer.

Profiling of concanavalin A-binding glycoproteins in human hepatic stellate cells activated with transforming growth factor-β1

Glycoproteins play important roles in maintaining normal cell functions depending on their glycosylations. Our previous study indicated that the abundance of glycoproteins recognized by concanavalin A (ConA) was increased in human hepatic stellate cells (HSCs) following activation by transforming growth factor-β1 (TGF-β1); however, little is known about the ConA-binding glycoproteins (CBGs) of HSCs. In this study, we employed a targeted glycoproteomics approach using lectin-magnetic particle conjugate-based liquid chromatography-tandem mass spectrometry to compare CBG profiles between LX-2 HSCs with and without activation by TGF-β1, with the aim of discovering novel CBGs and determining their possible roles in activated HSCs. A total of 54 and 77 proteins were identified in the quiescent and activated LX-2 cells, respectively. Of the proteins identified, 14.3% were glycoproteins and 73.3% were novel potential glycoproteins. Molecules involved in protein processing in the endoplasmic reticulum (e.g., calreticulin) and calcium signaling (e.g., 1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase β-2 [PLCB2]) were specifically identified in activated LX-2 cells. Additionally, PLCB2 expression was upregulated in the cytoplasm of the activated LX-2 cells, as well as in the hepatocytes and sinusoidal cells of liver cirrhosis tissues. In conclusion, the results of this study may aid future investigations to find new molecular mechanisms involved in HSC activation and antifibrotic therapeutic targets.

Differentially expressed glycosylated patterns of α-1-antitrypsin as serum biomarkers for the diagnosis of lung cancer

Lung cancer is the most common malignancy worldwide. Thus, there is a critical need for diagnostic biomarkers with adequate sensitivity and specificity for lung cancer detection. Glycans in glycoproteins are significantly altered in cancer, and may serve as a tool for identifying potential diagnostic biomarkers. Recent studies have reported changes in α-1-antitrypsin (A1AT) glycosylation in lung cancer serum, tissue and cell lines. In this study, a lectin microarray was used to detect glycosylation changes in serum A1AT from patients with lung adenocarcinoma (ADC), squamous cell lung cancer, small-cell lung cancer (SCLC) and benign pulmonary diseases. Differentially expressed glycosylated patterns of A1AT were identified by lectin arrays and were confirmed by lectin-based enzyme-linked immunosorbent assay (ELISA). We found that galactosylated A1AT could distinguish non-small-cell lung cancer (NSCLC) from benign pulmonary diseases (AUC = 0.834); fucosylated A1AT showed exceptional capability in distinguishing ADC from benign diseases (AUC = 0.919) or other lung cancer subtypes (AUC = 0.844), and A1AT containing poly-LacNAc could detect SCLC from benign diseases (AUC = 0.905) or NSCLC (AUC = 0.707). The present study indicates that glycosylated patterns of A1AT may serve as potential biomarkers for detection of lung cancer. Further studies in larger sample sizes are necessary to validate the clinical utility of these markers.

Protein O glycosylation regulates activation of hepatic stellate cells

It was reported that O glycosylation is associated with hepatic stellate cell activation and regulates collagen expression. In this study, we aimed to investigate the effect of O glycosylation on the activation of human hepatic stellate cells. We found that the inhibitor of O glycosylation, benzyl-α-GalNAc (2 and 4 mM), could significantly inhibit cells proliferation in a dose-dependent manner. Moreover, benzyl-α-GalNAc decreased the expressions of α-smooth muscle actin, collagen I, and collagen III. The results indicate that O glycosylation is involved in the activation of hepatic stellate cells.

Use of lectin microarray to differentiate gastric cancer from gastric ulcer

AIM: To investigate the feasibility of lectin microarray for differentiating gastric cancer from gastric ulcer.

METHODS: Twenty cases of human gastric cancer tissue and 20 cases of human gastric ulcer tissue were collected and processed. Protein was extracted from the frozen tissues and stored. The lectins were dissolved in buffer, and the sugar-binding specificities of lectins and the layout of the lectin microarray were summarized. The median of the effective data points for each lectin was globally normalized to the sum of medians of all effective data points for each lectin in one block. Formalin-fixed paraffin-embedded gastric cancer tissues and their corresponding gastric ulcer tissues were subjected to Ag retrieval. Biotinylated lectin was used as the primary antibody and HRP-streptavidin as the secondary antibody. The glycopatterns of glycoprotein in gastric cancer and gastric ulcer specimens were determined by lectin microarray, and then validated by lectin histochemistry. Data are presented as mean ± SD for the indicated number of independent experiments.

RESULTS: The glycosylation level of gastric cancer was significantly higher than that in ulcer. In gastric cancer, most of the lectin binders showed positive signals and the intensity of the signals was stronger, whereas the opposite was the case for ulcers. Significant differences in the pathological score of the two lectins were apparent between ulcer and gastric cancer tissues using the same lectin. For MPL and VVA, all types of gastric cancer detected showed stronger staining and a higher positive rate in comparison with ulcer, especially in the case of signet ring cell carcinoma and intra-mucosal carcinoma. GalNAc bound to MPL showed a significant increase. A statistically significant association between MPL and gastric cancer was observed. As with MPL, there were significant differences in VVA staining between gastric cancer and ulcer.

CONCLUSION: Lectin microarray can differentiate the different glycopatterns in gastric cancer and gastric ulcer, and the lectins MPL and VVA can be used as biomarkers.

Identification of hepatocellular carcinoma related genes with k-th shortest paths in a protein-protein interaction network

Hepatocellular carcinoma (HCC) is the most common type of liver cancer worldwide and one of the deadliest cancers in Asia. But at present, effective targets for HCC clinical therapy are still limited. The "guilt by association" rule suggests that interacting proteins share the same or similar functions and hence may be involved in the same pathway. This assumption can be used to identify disease related genes from protein association networks constructed from existing PPI data. Given the close association between Hepatitis B virus and Hepatitis B which may lead to HCC, here we develop a computational method to identify hepatocellular carcinoma related genes based on k-th shortest paths in the protein-protein interaction (PPI) network (we set k=1, 2 in this study). Finally, we found 33 genes whose p-values were less than 0.05, and most of them have been reported to be involved in HCC tumorigenesis and development. The results also provide a new reference for research into HCC oncogenesis and for development of new strategies for HCC clinical therapies.

Age- and sex-associated differences in the glycopatterns of human salivary glycoproteins and their roles against influenza A virus

Recent studies have elucidated that expression of certain glycoproteins in human saliva is increased or decreased according to age; meanwhile, human saliva may inhibit viral infection and prevent viral transmission. However, little is known about the age- and sex-associated differences in the glycopatterns of human salivary glycoproteins and their significant roles against influenza A virus (IVA). Here, we investigate the glycopatterns of human salivary glycoproteins with 180 healthy saliva samples divided into six age/sex groups using lectin microarrays and fabricate saliva microarrays to validate the terminal carbohydrate moieties of glycoproteins in individual saliva samples. Furthermore, we assess the inhibiting and neutralizing activity of saliva against two strains of influenza A (H9N2) virus. We find that seven lectins (e.g., MAL-II and SNA) show significant age differences in both females and males, and seven lectins (e.g., WFA and STL) show significant sex differences in children, adults and elderly people. Interestingly, we observe that elderly individuals have strongest resistance to IVA partly by presenting more terminal α2-3/6-linked sialic acid residues in their saliva, which bind with the influenza viral hemagglutinations. We conclude that age- and sex-associated differences in the glycopatterns of human salivary glycoproteins may provide pivotal information to help understand some age related diseases and physiological phenomena.

Glycoproteomic analysis of tissues from patients with colon cancer using lectin microarrays and nanoLC-MS/MS

The current study evaluated the glycoproteomic profile of tissues from colon cancer patients. The lectin microarray was first performed to compare the glycoprotein profiles between colon cancer and matched normal tissues. Level of N-acetylglucosamine (GlcNAc) that Solanum tuberosum lectin (STL) bound was found to be elevated in colon cancer, which was verified through lectin histochemistry. The subsequent glycoproteomic analysis based on STL enrichment of glycoproteins followed by label-free quantitative nano liquid chromatography-mass spectrometry/mass spectrometry (nanoLC-MS/MS) analysis identified 72 proteins in high confidence. Among these proteins, 17 were exclusively detected in cancer tissues, and 14 were significantly upregulated in tumor tissues. Annexin A1 and HSP90β were chosen for further investigation by immunoprecipitation coupled with lectin blots, western blots and tissue microarrays. Both Annexin A1 and HSP90β were GlcNAcylated, and their protein expressions were elevated in colon cancer, compared to normal tissues. Moreover, specific changes of GlcNAc abundances in Annexin A1 and HSP90β suggested that tumor-specific glycan patterns could serve as candidate biomarkers of colon cancer for distinguishing cancer patients from healthy individuals.

Isolation and identification of mannose-binding proteins and estimation of their abundance in sera from hepatocellular carcinoma patients

The interaction of glycan-binding proteins (GBPs) and glycans plays a significant biological role that ranges from cell-cell recognition to cell trafficking, and glycoprotein targeting. The anomalies of GBPs related to the types and/or quantities were not clearly known in cancer incidence. It is imperative to identify and annotate the GBPs related with the canceration. Here the mannose-binding proteins (MBPs) from the clinical sera were isolated and identified by the mannose-magnetic particle conjugates and the high-accuracy MS analysis. Seventy-five MBPs from normal donors' sera and 79 MBPs from hepatocellular carcinoma patients' sera were identified and annotated. By using the stringent criteria of exponentially modified protein abundance index (emPAI) quantification, 12 MBPs were estimated to be significantly upregulated (emPAI ratio > 4) and nine MBPs were estimated to be significantly downregulated (emPAI ratio < 0.25) in the hepatocellular carcinoma sera. Real-time quantitative PCR, Western blotting, and protein microarrays were also used to confirm the altered MBPs expression level and the specific binding between the isolated MBPs and mannose. The sequence recognition motifs and structure preference of the isolated MBPs were characterized. The functional enrichment analysis revealed that over 57% of the isolated MBPs were binding protein and the upregulated MBPs were involved in cell death, tumor progression, and macromolecular complex remodeling.

Analysis of glycan-related genes expression and glycan profiles in mice with liver fibrosis

Protein glycosylation plays an important role in the pathogenesis and progression of various liver diseases. However, little is known about the precise alterations in protein glycosylation or the potential correlation between glycan-related genes expression and glycan profiles in liver fibrosis. The aim of the study was to investigate potential associations between glycan-related genes expression and glycan profiles to evaluate liver fibrosis in a mouse model. Analyses of glycan-related genes expression and glycan profiles were performed using oligonucleotide microarrays and lectin microarrays, respectively. Real-time PCR and Western blot were used to confirm any altered glycan-related genes expression levels and protein levels. Moreover, altered glycan patterns on the surface of hepatocytes were verified by lectin histochemistry. These results revealed that the mRNA levels of 10 glycan-related genes were significantly altered in fibrotic liver. Furthermore, we observed an increase in multivalent sialic acid, poly-LacNAc, sialyl-T-antigen, Fucoseα-1,3/6GlcNAc, and GalNAcα1-3Gal in fibrotic liver specimens, whereas GlcNAc oligomers was decreased in fibrotic liver. Our findings indicated that the synthetic pathway of "Tn antigen → T antigen (core-1) → sialyl-T antigen" was activated for O-glycan during the process of liver fibrosis.