Inflammatory cytokines regulate the expression of glycosyltransferases involved in the biosynthesis of tumor-associated sialylated glycans in pancreatic cancer cell lines

Exploring the diverse biological significance and roles of fucosylated oligosaccharides

Long since, carbohydrates were thought to be used just as an energy source and structural material. However, in recent years, with the emergence of the field of glycobiology and advances in glycomics, much has been learned about the biological role of oligosaccharides, a carbohydrate polymer containing a small number of monosaccharides, in cell-cell interaction, signal transduction, immune response, pathogen adhesion processes, early embryogenesis, and apoptosis. The function of oligosaccharides in these processes is diversified by fucosylation, also known as modification of oligosaccharides. Fucosylation has allowed the identification of more than 100 different oligosaccharide structures that provide functional diversity. ABO blood group and Lewis antigens are among the best known fucosyl-linked oligosaccharides. In addition, the antigens in the ABO system are composed of various sugar molecules, including fucosylated oligosaccharides, and Lewis antigens are structurally similar to ABO antigens but differ in the linkage of sugars. Variation in blood group antigen expression affects the host's susceptibility to many infections. However, altered expression of ABO and Lewis antigens is related with prognosis in carcinoma types. In addition, many pathogens recognize and bind to human tissues using a protein receptor with high affinity for the fucose molecule in glycoconjugates, such as lectin. Fucosylated oligosaccharides also play vital roles during fertilization and early embryogenesis. Learning and memory-related processes such as neurite growth, neurite migration, and synapse formation seen during the development of the brain, which is among the first organs to develop in embryogenesis, are regulated by fucosylated oligosaccharides. In conclusion, this review mentions the vital roles of fucosylated oligosaccharides in biology, drawing attention to their importance in the development of chemical tools to be used in function analysis and the investigation of various therapeutic targets.

Regulation of sialic acid metabolism in cancer

Sialic acid, the terminal structure of cell surface glycans, has essential functions in regulating immune response, cell-to-cell communication, and cell adhesion. More importantly, an increased level of sialic acid, termed hypersialylation, has emerged as a commonly observed phenotype in cancer. Therefore, targeting sialic acid ligands (sialoglycans) and their receptors (Siglecs) may provide a new therapeutic approach for cancer immunotherapy. We highlight the complexity of the sialic acid metabolism and its involvement in malignant transformation within individual cancer subtypes. In this review, we focus on the dysregulation of sialylation, the intricate nature of sialic acid synthesis, and clinical perspective. We aim to provide a brief insight into the mechanism of hypersialylation and how our understanding of these processes can be leveraged for the development of novel therapeutics.

FUT3 facilitates glucose metabolism of lung adenocarcinoma via activation of NF-κB pathway

OBJECTIVE

Fucosyltransferases (FUTs) molecules have been identified to be involved in carcinogenesis of malignant tumors. Nevertheless, the biological function of fucosyltransferases-3 (FUT3) in lung adenocarcinoma (LUAD) malignant phenotype remains unclear. Herein, we investigated the association between FUT3 and LUAD pathological process.

METHODS

Immunochemistry, RT-qPCR and western blot assays were conducted to evaluate the expression of FUT3 in LUAD and corresponding adjacent tissues. The prognostic value of FUT3 was assessed via Kaplan‑Meier plotter database. The biological process and potential mechanism of FUT3 in LUAD were conducted via GSEA. Additionally, immunofluorescence and metabolite activity detection were performed to determine the potential role of FUT3 in LUAD glucose metabolism. The active biomarkers associated with NF-κB signaling pathway were detected via western blot. Subcutaneous tumor model was conducted to analyze the effect of FUT3 on tumorigenesis of LUAD.

RESULTS

FUT3 was remarkably upregulated in LUAD tissues compared with adjacent tissues from individuals. FUT3 overexpression may predict poor prognosis of LUAD patients. Knockdown of FUT3 significantly inhibited tumor proliferation, migration and glucometabolic alteration in LUAD cells. Moreover, GSEA demonstrated that elevated FUT3 was positively related to NF-κB signaling pathway. Additionally, in vitro and in vivo assays also indicated that downregulation of FUT3 resulted in the suppression of oncogenesis and glucose metabolism via inactivation of NF-κB pathway.

CONCLUSION

Our findings demonstrated that FUT3 was involved in glucometabolic process and tumorigenesis of LUAD via NF-κB signaling pathway. FUT3 may be an optimal target for diagnosis and treatment of LUAD patients.

Heightened Proinflammatory Glycosylation of Borrelia burgdorferi IgG Antibodies in Synovial Fluid in Patients With Antibiotic-Refractory Lyme Arthritis

OBJECTIVE

Terminal glycans on the Fc portion of IgG antibodies are critical for antibody-triggered, proinflammatory or antiinflammatory responses. We undertook this study to compare glycan profiles of total IgG1 and Borrelia burgdorferi (Bb)-specific IgG1 antibodies in patients with oral antibiotic-responsive or antibiotic-refractory Lyme arthritis (LA).

METHODS

Following affinity-column processing, glycan profiles of IgG antibodies were determined in serum and synovial fluid (SF) samples of 21 LA patients using glycoblotting with hydrazide glycan enrichment and determination of glycan structure by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Correlations between glycan profiles and treatment outcomes were analyzed.

RESULTS

Compared with patients with antibiotic-refractory LA, those with antibiotic-responsive LA had total and Bb-specific IgG1 antibody glycans with less intense inflammatory profiles, containing lower percentages of N-acetylglucosamine (GlcNAc) and bisecting GlcNAc and higher percentages of galactose and fucose. In contrast, patients with antibiotic-refractory LA prior to receiving IV antibiotic therapy had total IgG1 and Bb IgG1 antibodies with maximal, minimally opposed, proinflammatory glycan profiles, containing high percentages of GlcNAc and bisecting GlcNAc, intermediate percentages with galactose and fucose, and low percentages with N-acetylneuraminic acid (sialic acid). Patients with refractory LA who were first seen with synovitis after receiving IV antibiotic therapy still had Bb IgG1 antibodies with strongly inflammatory glycan profiles, but their inflammatory potential appeared to be waning.

CONCLUSION

Patients with oral antibiotic-responsive LA had Bb IgG1 antibodies with more balanced proinflammatory/antiinflammatory glycan profiles, whereas patients with antibiotic-refractory LA had Bb IgG1 antibodies with maximal, minimally opposed, proinflammatory glycan profiles. Among patients with antibiotic-refractory LA, antibodies with this unbalanced inflammatory glycan profile may have a role in sustaining maladaptive joint inflammation.

Chemokine-mucinome interplay in shaping the heterogeneous tumor microenvironment of pancreatic cancer

Pancreatic cancer (PC) is exemplified by a complex immune-suppressive, fibrotic tumor microenvironment (TME), and aberrant expression of mucins. The constant crosstalk between cancer cells, cancer-associated fibroblasts (CAFs), and the immune cells mediated by the soluble factors and inflammatory mediators including cytokines, chemokines, reactive oxygen species (ROS) promote the dynamic temporal switch towards an immune-escape phenotype in the neoplastic cells and its microenvironment that bolsters disease progression. Chemokines have been studied in PC pathogenesis, albeit poorly in the context of mucins, tumor glycocalyx, and TME heterogeneity (CAFs and immune cells). With correlative analysis from PC patients' transcriptome data, support from available literature, and scientific arguments-based speculative extrapolations in terms of disease pathogenesis, we have summarized in this review a comprehensive understanding of chemokine-mucinome interplay during stromal modulation and immune-suppression in PC. Future studies should focus on deciphering the complexities of chemokine-mediated control of glycocalyx maturation, immune infiltration, and CAF-associated immune suppression. Knowledge extracted from such studies will be beneficial to mechanistically correlate the mucin-chemokine abundance in serum versus pancreatic tumors of patients, which may aid in prognostication and stratification of PC patients for immunotherapy.

Role of tumor cell sialylation in pancreatic cancer progression

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies and is currently the third leading cause of cancer death. The aggressiveness of PDAC stems from late diagnosis, early metastasis, and poor efficacy of current chemotherapies. Thus, there is an urgent need for effective biomarkers for early detection of PDAC and development of new therapeutic strategies. It has long been known that cellular glycosylation is dysregulated in pancreatic cancer cells, however, tumor-associated glycans and their cognate glycosylating enzymes have received insufficient attention as potential clinical targets. Aberrant glycosylation affects a broad range of pathways that underpin tumor initiation, metastatic progression, and resistance to cancer treatment. One of the prevalent alterations in the cancer glycome is an enrichment in a select group of sialylated glycans including sialylated, branched N-glycans, sialyl Lewis antigens, and sialylated forms of truncated O-glycans such as the sialyl Tn antigen. These modifications affect the activity of numerous cell surface receptors, which collectively impart malignant characteristics typified by enhanced cell proliferation, migration, invasion and apoptosis-resistance. Additionally, sialic acids on tumor cells engage inhibitory Siglec receptors on immune cells to dampen anti-tumor immunity, further promoting cancer progression. The goal of this review is to summarize the predominant changes in sialylation occurring in pancreatic cancer, the biological functions of sialylated glycoproteins in cancer pathogenesis, and the emerging strategies for targeting sialoglycans and Siglec receptors in cancer therapeutics.

Altered glycosylation in pancreatic cancer and beyond

Pancreatic ductal adenocarcinoma (PDA) is one of the deadliest cancers and is projected to soon be the second leading cause of cancer death. Median survival of PDA patients is 6-10 mo, with the majority of diagnoses occurring at later, metastatic stages that are refractory to treatment and accompanied by worsening prognoses. Glycosylation is one of the most common types of post-translational modifications. The complex landscape of glycosylation produces an extensive repertoire of glycan moieties, glycoproteins, and glycolipids, thus adding a dynamic and tunable level of intra- and intercellular signaling regulation. Aberrant glycosylation is a feature of cancer progression and influences a broad range of signaling pathways to promote disease onset and progression. However, despite being so common, the functional consequences of altered glycosylation and their potential as therapeutic targets remain poorly understood and vastly understudied in the context of PDA. In this review, the functionality of glycans as they contribute to hallmarks of PDA are highlighted as active regulators of disease onset, tumor progression, metastatic capability, therapeutic resistance, and remodeling of the tumor immune microenvironment. A deeper understanding of the functional consequences of altered glycosylation will facilitate future hypothesis-driven studies and identify novel therapeutic strategies in PDA.

Bringing to Light the Risk of Colorectal Cancer in Inflammatory Bowel Disease: Mucosal Glycosylation as a Key Player

Colitis-associated cancer is a major complication of inflammatory bowel disease remaining an important clinical challenge in terms of diagnosis, screening, and prognosis. Inflammation is a driving factor both in inflammatory bowel disease and cancer, but the mechanism underlying the transition from colon inflammation to cancer remains to be defined. Dysregulation of mucosal glycosylation has been described as a key regulatory mechanism associated both with colon inflammation and colorectal cancer development. In this review, we discuss the major molecular mechanisms of colitis-associated cancer pathogenesis, highlighting the role of glycans expressed at gut epithelial cells, at lamina propria T cells, and in serum proteins in the regulation of intestinal inflammation and its progression to colon cancer, further discussing its potential clinical and therapeutic applications.

An NF-κB- and Therapy-Related Regulatory Network in Glioma: A Potential Mechanism of Action for Natural Antiglioma Agents

High-grade gliomas are among the most aggressive malignancies, with significantly low median survival. Recent experimental research in the field has highlighted the importance of natural substances as possible antiglioma agents, also known for their antioxidant and anti-inflammatory action. We have previously shown that natural substances target several surface cluster of differentiation (CD) markers in glioma cells, as part of their mechanism of action. We analyzed the genome-wide NF-κB binding sites residing in consensus regulatory elements, based on ENCODE data. We found that NF-κB binding sites reside adjacent to the promoter regions of genes encoding CD markers targeted by antiglioma agents (namely, CD15/FUT4, CD28, CD44, CD58, CD61/SELL, CD71/TFRC, and CD122/IL2RB). Network and pathway analysis revealed that the markers are associated with a core network of genes that, altogether, participate in processes that associate tumorigenesis with inflammation and immune evasion. Our results reveal a core regulatory network that can be targeted in glioblastoma, with apparent implications in individuals that suffer from this devastating malignancy.

Differential H. pylori-Induced MAPK Responses Regulate Lewis Antigen Expression and Colonization Density on Gastric Epithelial Cells Between Children and Adults

Helicobacter pylori causes gastrointestinal diseases, the manifestations of diseases are more serious in adults than in children. Lewis antigen expressions on the gastric epithelium serves as receptors targeted by H. pylori. Moreover, the MAPK signaling pathway involves glycoprotein synthesis of Lewis antigens. We aimed to investigate whether differences in H. pylori-induced MAPK responses mediate gastric Lewis antigens expression and colonization density differently in children and adults. We used human stomach fetal epithelium (HSFE) and SV40-immortalized human normal gastric epithelial (GES-1) cell lines to mimic primary gastric epithelium of children and adults, respectively. H. pylori colonization intensity and Lewis antigens were significantly higher in GES-1 than in HSFE cells, whereas IL-8 and IL-6 levels were significantly higher in HSFE than in GES-1 cells after infection. c-Jun N-terminal kinase (JNK) siRNA and inhibitor (SP600125) experiments showed that Lewis antigen expression and H. pylori colonization were reduced in GES-1 cells but increased in HSFE cells. Furthermore, p-p38 intensity was significantly higher in the superficial epithelium of the children than in the adults with/without H. pylori infection. The overexpression of p38 in GES-1 cells downregulated H. pylori-induced JNK activity mimicking H. pylori infection in children. In conclusion, a higher p38 expression in gastric epithelium counteracting JNK activity in children may contribute to lower Lewis antigen expression and colonization density than in adults after H. pylori infection.

Targeting Tumor Glycans for Cancer Therapy: Successes, Limitations, and Perspectives

Simple Summary

Aberrant glycosylation is a common feature of many cancers, and it plays crucial roles in tumor development and biology. Cancer progression can be regulated by several physiopathological processes controlled by glycosylation, such as cell–cell adhesion, cell–matrix interaction, epithelial-to-mesenchymal transition, tumor proliferation, invasion, and metastasis. Different mechanisms of aberrant glycosylation lead to the formation of tumor-associated carbohydrate antigens (TACAs), which are suitable for selective cancer targeting, as well as novel antitumor immunotherapy approaches. This review summarizes the strategies developed in cancer immunotherapy targeting TACAs, analyzing molecular and cellular mechanisms and state-of-the-art methods in clinical oncology.

Abstract

Aberrant glycosylation is a hallmark of cancer and can lead to changes that influence tumor behavior. Glycans can serve as a source of novel clinical biomarker developments, providing a set of specific targets for therapeutic intervention. Different mechanisms of aberrant glycosylation lead to the formation of tumor-associated carbohydrate antigens (TACAs) suitable for selective cancer-targeting therapy. The best characterized TACAs are truncated O-glycans (Tn, TF, and sialyl-Tn antigens), gangliosides (GD2, GD3, GM2, GM3, fucosyl-GM1), globo-serie glycans (Globo-H, SSEA-3, SSEA-4), Lewis antigens, and polysialic acid. In this review, we analyze strategies for cancer immunotherapy targeting TACAs, including different antibody developments, the production of vaccines, and the generation of CAR-T cells. Some approaches have been approved for clinical use, such as anti-GD2 antibodies. Moreover, in terms of the antitumor mechanisms against different TACAs, we show results of selected clinical trials, considering the horizons that have opened up as a result of recent developments in technologies used for cancer control.

Fucosylation in Urological Cancers

Fucosylation is an oligosaccharide modification that plays an important role in immune response and malignancy, and specific fucosyltransferases (FUTs) catalyze the three types of fucosylations: core-type, Lewis type, and H type. FUTs regulate cancer proliferation, invasiveness, and resistance to chemotherapy by modifying the glycosylation of signaling receptors. Oligosaccharides on PD-1/PD-L1 proteins are specifically fucosylated, leading to functional modifications. Expression of FUTs is upregulated in renal cell carcinoma, bladder cancer, and prostate cancer. Aberrant fucosylation in prostate-specific antigen (PSA) could be used as a novel biomarker for prostate cancer. Furthermore, elucidation of the biological function of fucosylation could result in the development of novel therapeutic targets. Further studies are needed in the field of fucosylation glycobiology in urological malignancies.

Targeting Pyrimidine Metabolism in the Era of Precision Cancer Medicine

Metabolic rewiring is considered as a primary feature of cancer. Malignant cells reprogram metabolism pathway in response to various intrinsic and extrinsic drawback to fuel cell survival and growth. Among the complex metabolic pathways, pyrimidine biosynthesis is conserved in all living organism and is necessary to maintain cellular fundamental function (i.e. DNA and RNA biosynthesis). A wealth of evidence has demonstrated that dysfunction of pyrimidine metabolism is closely related to cancer progression and numerous drugs targeting pyrimidine metabolism have been approved for multiple types of cancer. However, the non-negligible side effects and limited efficacy warrants a better strategy for negating pyrimidine metabolism in cancer. In recent years, increased studies have evidenced the interplay of oncogenic signaling and pyrimidine synthesis in tumorigenesis. Here, we review the recent conceptual advances on pyrimidine metabolism, especially dihydroorotate dehydrogenase (DHODH), in the framework of precision oncology medicine and prospect how this would guide the development of new drug precisely targeting the pyrimidine metabolism in cancer.

Immunization with anti-Tn immunogen in maternal rats protects against hyperoxia-induced kidney injury in newborn offspring

BACKGROUND

Neonatal hyperoxia increases oxidative stress and adversely disturbs glomerular and tubular maturity. Maternal Tn immunization induces anti-Tn antibody titer and attenuates hyperoxia-induced lung injury in neonatal rats.

METHODS

We intraperitoneally immunized female Sprague-Dawley rats (6 weeks old) with Tn immunogen (50 μg/dose) or carrier protein five times at biweekly intervals on 8, 6, 4, 2, and 0 weeks before the delivery day. The pups were reared for 2 weeks in either room air (RA) or in 85% oxygen-enriched atmosphere (O₂), thus generating four study groups, namely carrier protein + RA, Tn vaccine + RA, carrier protein + O₂, and Tn vaccine + O₂. On postnatal day 14, the kidneys were harvested for the oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG), nuclear factor-κB (NF-κB), and collagen expression and histological analyses.

RESULTS

Hyperoxia reduced body weight, induced tubular and glomerular injuries, and increased 8-OHdG and NF-κB expression and collagen deposition in the kidneys. By contrast, maternal Tn immunization reduced kidney injury and collagen deposition in neonatal rats. Furthermore, kidney injury attenuation was accompanied by a reduction in 8-OHdG and NF-κB expression.

CONCLUSION

Maternal Tn immunization protects against hyperoxia-induced kidney injury in neonatal rats by attenuating oxidative stress and NF-κB activity.

IMPACT

Hyperoxia increased nuclear factor-κB (NF-κB) activity and collagen deposition in neonatal rat kidney. Maternal Tn immunization reduced kidney injury as well as collagen deposition in neonatal rats. Maternal Tn immunization reduced kidney injury and was associated with a reduction in 8-hydroxy-2'-deoxyguanosine and NF-κB activity. Tn vaccine can be a promising treatment modality against hyperoxia-induced kidney injury in neonates.

Expression and prognostic analyses of SCAMPs in pancreatic adenocarcinoma

Due to the difficulties in early diagnosis of pancreatic adenocarcinoma (PAAD), many patients fail to receive optimal therapeutic regimens. The Secretory-Carrier-Membrane-Proteins (SCAMPs) are known to be dysregulated in a range of human diseases due to their characterized roles in mammalian cell exocytosis inferred from their functions as integral membrane proteins. However, the expression and prognostic value of SCAMPs in PAAD is poorly characterized. We compared cancer vs. healthy tissue and found that the expression of SCAMPs1-4 was upregulated in PAAD compared to normal tissue. In contrast, SCAMP5 expression was downregulated in PAAD. Moreover, the expression of SCAMPs1-4 was enhanced in PAAD cell lines according to Cancer Cell Line public database. Furthermore, the HPA, GEPIA databases and immunohistochemical analysis from 238 patients suggested that the loss of SCAMP1 led to improved overall survival (OS), whilst lower SCAMP5 levels led to a poorer OS. The univariate and multivariate analysis showed that SCAMP1 and SCAMP5 expression were independent prognostic factors of PAAD. In addition, the cBioPortal for Cancer Genomics, LinkedOmics datasets, and the GEPIA were used to identify the co-expression genes of SCAMP1,5 and the correlation between SCAMPs members. We conclude that SCAMPs 1 and 5 significantly represent promising diagnosis and prognostic biomarkers.

The Tumour Microenvironment and Circulating Tumour Cells: A Partnership Driving Metastasis and Glycan-Based Opportunities for Cancer Control

Circulating tumour cells (CTC) are rare cells that actively detach or are shed from primary tumours into the lymph and blood. Some CTC subpopulations gain the capacity to survive, home and colonize distant locations, forming metastasis. This results from a multifactorial process in which cancer cells optimize motility, invasion, immune escape and cooperative relationships with microenvironmental cues. Here we present evidences of a self-fuelling molecular crosstalk between cancer cells and the tumour stroma supporting the main milestones leading to metastasis. We discuss how the tumour microenvironment supports pre-metastatic niches and CTC development and ultimately dictates CTC fate in targeted organs. Finally, we highlight the key role played by protein glycosylation in metastasis development, its prompt response to microenvironmental stimuli and the tremendous potential of glycan-based molecular signatures for liquid biopsies and targeted therapeutics.

High Throughput Multiplex SNP-analysis in Chronic Obstructive Pulmonary Disease and Lung Cancer

Background:

A number of human inflammatory diseases and tumors have been shown to cause alterations in the glycosylation pattern of plasma proteins in a specific manner. These highly variable and versatile post-translational modifications finetune protein functions by influencing sorting, folding, enzyme activity and subcellular localization. However, relatively little is known about regulatory factors of this procedure and about the accurate causative connection between glycosylation and disease.

Objective:

The aim of the present study was to investigate whether certain single nucleotide polymorphisms (SNPs) in genes encoding glycosyltransferases and glycosidases could be associated with elevated risk for chronic obstructive pulmonary disease (COPD) and lung adenocarcinoma.

Methods:

A total of 32 SNPs localized in genes related to N-glycosylation were selected for the association analysis. Polymorphisms with putative biological functions (missense or regulatory variants) were recruited. SNPs were genotyped by a TaqMan OpenArray platform. A single base extension-based method in combination with capillary gel electrophoresis was used for verification.

Results:

The TaqMan OpenArray approach provided accurate and reliable genotype data (global call rate: 94.9%, accuracy: 99.6%). No significant discrepancy was detected between the obtained and expected genotype frequency values (Hardy–Weinberg equilibrium) in the healthy control sample group in case of any SNP confirming reliable sampling and genotyping. Allele frequencies of the rs3944508 polymorphism localized in the 3’ UTR of the MGAT5 gene significantly differed between the sample groups compared.

Conclusion:

Our results suggest that the rs34944508 SNP might modulate the risk for lung cancer by influencing the expression of MGAT5. This enzyme catalyzes the addition of N-acetylglucosamine (GlcNAc) in beta 1-6 linkage to the alpha-linked mannose of biantennary N-linked oligosaccharides, thus, increasing branching that is the characteristic of invasive malignancies.

Tri-antennary tri-sialylated mono-fucosylated glycan of alpha-1 antitrypsin as a non-invasive biomarker for non-alcoholic steatohepatitis: a novel glycobiomarker for non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is a progressive form of non-alcoholic fatty liver disease (NAFLD) that may lead to liver cirrhosis or hepatocellular carcinoma. Here, we examined the diagnostic utility of tri-antennary tri-sialylated mono-fucosylated glycan of alpha-1 antitrypsin (AAT-A3F), a non-invasive glycobiomarker identified in a previous study of NASH diagnosis. This study included 131 biopsy-proven Japanese patients with NAFLD. We evaluated the utility of AAT-A3F in NASH diagnosis, and conducted genetic analysis to analyse the mechanism of AAT-A3F elevation in NASH. Serum AAT-A3F concentrations were significantly higher in NASH patients than in NAFL patients, and in patients with fibrosis, lobular inflammation, and ballooning. Hepatic FUT6 gene expression was significantly higher in NASH than in NAFL. IL-6 expression levels were significantly higher in NASH than in NAFL and showed a positive correlation with FUT6 expression levels. The serum-AAT-A3F levels strongly correlated with hepatic FUT6 expression levels. AAT-A3F levels increased with fibrosis, pathological inflammation, and ballooning in patients with NAFLD and may be useful for non-invasive diagnosis of NASH from the early stages of fibrosis.

Cross-talk between Colon Cells and Macrophages Increases ST6GALNAC1 and MUC1-sTn Expression in Ulcerative Colitis and Colitis-Associated Colon Cancer

Patients with ulcerative colitis have an increased risk of developing colitis-associated colon cancer (CACC). Changes in glycosylation of the oncoprotein MUC1 commonly occur in chronic inflammation, including ulcerative colitis, and this abnormally glycosylated MUC1 promotes cancer development and progression. It is not known what causes changes in glycosylation of MUC1. Gene expression profiling of myeloid cells in inflamed and malignant colon tissues showed increased expression levels of inflammatory macrophage-associated cytokines compared with normal tissues. We analyzed the involvement of macrophage-associated cytokines in the induction of aberrant MUC1 glycoforms. A coculture system was used to examine the effects of M1 and M2 macrophages on glycosylation-related enzymes in colon cancer cells. M2-like macrophages induced the expression of the glycosyltransferase ST6GALNAC1, an enzyme that adds sialic acid to O-linked GalNAc residues, promoting the formation of tumor-associated sialyl-Tn (sTn) O-glycans. Immunostaining of ulcerative colitis and CACC tissue samples confirmed the elevated number of M2-like macrophages as well as high expression of ST6GALNAC1 and the altered MUC1-sTn glycoform on colon cells. Cytokine arrays and blocking antibody experiments indicated that the macrophage-dependent ST6GALNAC1 activation was mediated by IL13 and CCL17. We demonstrated that IL13 promoted phosphorylation of STAT6 to activate transcription of ST6GALNAC1. A computational model of signaling pathways was assembled and used to test IL13 inhibition as a possible therapy. Our findings revealed a novel cellular cross-talk between colon cells and macrophages within the inflamed and malignant colon that contributes to the pathogenesis of ulcerative colitis and CACC.See related Spotlight on p. 160.

Primary Human Natural Killer Cells Retain Proinflammatory IgG1 at the Cell Surface and Express CD16a Glycoforms with Donor-dependent Variability

Post-translational modification confers diverse functional properties to immune system proteins. The composition of serum proteins such as immunoglobulin G (IgG) strongly associates with disease including forms lacking a fucose modification of the crystallizable fragment (Fc) asparagine(N)-linked glycan that show increased effector function, however, virtually nothing is known about the composition of cell surface receptors or their bound ligands in situ because of low abundance in the circulating blood. We isolated primary NK cells from apheresis filters following plasma or platelet donation to characterize the compositional variability of Fc γ receptor IIIa/CD16a and its bound ligand, IgG1. CD16a N162-glycans showed the largest differences between donors; one donor displayed only oligomannose-type N-glycans at N162 that correlate with high affinity IgG1 Fc binding whereas the other donors displayed a high degree of compositional variability at this site. Hybrid-type N-glycans with intermediate processing dominated at N45 and highly modified, complex-type N-glycans decorated N38 and N74 from all donors. Analysis of the IgG1 ligand bound to NK cell CD16a revealed a sharp decrease in antibody fucosylation (43.2 ± 11.0%) versus serum from the same donors (89.7 ± 3.9%). Thus, NK cells express CD16a with unique modification patterns and preferentially bind IgG1 without the Fc fucose modification at the cell surface.

Extracellular Vesicles in Type 1 Diabetes: Messengers and Regulators

PURPOSE OF REVIEW

Theories about the pathogenesis of type 1 diabetes (T1D) refer to the potential of primary islet inflammatory signaling as a trigger for the loss of self-tolerance leading to disease onset. Emerging evidence suggests that extracellular vesicles (EV) may represent the missing link between inflammation and autoimmunity. Here, we review the evidence for a role of EV in the pathogenesis of T1D, as well as discuss their potential value in the clinical sphere, as biomarkers and therapeutic agents.

RECENT FINDINGS

EV derived from β cells are enriched in diabetogenic autoantigens and miRNAs that are selectively sorted and packaged. These EV play a pivotal role in antigen presentation and cell to cell communication leading to activation of autoimmune responses. Furthermore, recent evidence suggests the potential of EV as novel tools in clinical diagnostics and therapeutic interventions. In-depth analysis of EV cargo using modern multi-parametric technologies may be useful in enhancing our understanding of EV-mediated immune mechanisms and in identifying robust biomarkers and therapeutic strategies for T1D.

ST6GAL1: A key player in cancer

Aberrant glycosylation is a universal feature of cancer cells and there is now overwhelming evidence that glycans can modulate pathways intrinsic to tumour cell biology. Glycans are important in all of the cancer hallmarks and there is a renewed interest in the glycomic profiling of tumours to improve early diagnosis, determine patient prognosis and identify targets for therapeutic intervention. One of the most widely occurring cancer associated changes in glycosylation is abnormal sialylation which is often accompanied by changes in sialyltransferase activity. Several sialyltransferases are implicated in cancer, but in recent years ST6 β-galactoside α-2,6-sialyltransferase 1 (ST6GAL1) has become increasingly dominant in the literature. ST6GAL1 catalyses the addition of α2,6-linked sialic acids to terminal N-glycans and can modify glycoproteins and/or glycolipids. ST6GAL1 is upregulated in numerous types of cancer (including pancreatic, prostate, breast and ovarian cancer) and can promote growth, survival and metastasis. The present review discusses ST6GAL in relation to the hallmarks of cancer, and highlights its key role in multiple mechanisms intrinsic to tumour cell biology.

Protein Glycosylation and Tumor Microenvironment Alterations Driving Cancer Hallmarks

Decades of research have disclosed a plethora of alterations in protein glycosylation that decisively impact in all stages of disease and ultimately contribute to more aggressive cell phenotypes. The biosynthesis of cancer-associated glycans and its reflection in the glycoproteome is driven by microenvironmental cues and these events act synergistically toward disease evolution. Such intricate crosstalk provides the molecular foundations for the activation of relevant oncogenic pathways and leads to functional alterations driving invasion and disease dissemination. However, it also provides an important source of relevant glyco(neo)epitopes holding tremendous potential for clinical intervention. Therefore, we highlight the transversal nature of glycans throughout the currently accepted cancer hallmarks, with emphasis on the crosstalk between glycans and the tumor microenvironment stromal components. Focus is also set on the pressing need to include glycans and glycoconjugates in comprehensive panomics models envisaging molecular-based precision medicine capable of improving patient care. We foresee that this may provide the necessary rationale for more comprehensive studies and molecular-based intervention.

Maternal Tn Immunization Attenuates Hyperoxia-Induced Lung Injury in Neonatal Rats Through Suppression of Oxidative Stress and Inflammation

Hyperoxia therapy is often required to treat newborns with respiratory disorders. Prolonged hyperoxia exposure increases oxidative stress and arrests alveolar development in newborn rats. Tn antigen is N-acetylgalactosamine residue that is one of the most remarkable tumor-associated carbohydrate antigens. Tn immunization increases the serum anti-Tn antibody titers and attenuates hyperoxia-induced lung injury in adult mice. We hypothesized that maternal Tn immunizations would attenuate hyperoxia-induced lung injury through the suppression of oxidative stress in neonatal rats. Female Sprague-Dawley rats (6 weeks old) were intraperitoneally immunized five times with Tn (50 μg/dose) or carrier protein at biweekly intervals on 8, 6, 4, 2, and 0 weeks before the day of delivery. The pups were reared in room air (RA) or 2 weeks of 85% O₂, creating the four study groups: carrier protein + RA, Tn vaccine + RA, carrier protein + O₂, and Tn vaccine + O₂. The lungs were excised for oxidative stress, cytokine, vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) expression, and histological analysis on postnatal day 14. Blood was withdrawn from dams and rat pups to check anti-Tn antibody using western blot. We observed that neonatal hyperoxia exposure reduced the body weight, increased 8-hydroxy-2-deoxyguanosine (8-OHdG) expression and lung cytokine (interleukin-4), increased mean linear intercept (MLI) values, and decreased vascular density and VEGF and PDGF-B expressions. By contrast, Tn immunization increased maternal and neonatal serum anti-Tn antibody titers on postnatal day 14, reduced MLI, and increased vascular density and VEGF and PDGF-B expressions to normoxic levels. Furthermore, the alleviation of lung injury was accompanied by a reduction in lung cytokine and 8-OHdG expression. Therefore, we propose that maternal Tn immunization attenuates hyperoxia-induced lung injury in neonatal rats through the suppression of oxidative stress and inflammation.

The effect of streptozotocin-induced hyperglycemia on N-and O-linked protein glycosylation in mouse ovary

Post-translational modification of proteins namely glycosylation influences cellular behavior, structural properties and interactions including during ovarian follicle development and atresia. However, little is known about protein glycosylation changes occurring in diabetes mellitus in ovarian tissues despite the well-known influence of diabetes on the outcome of successful embryo implantation. In our study, the use of PGC chromatography-ESI mass spectrometry in negative ion mode enabled the identification of 138 N-glycans and 6 O-glycans on the proteins of Streptozotocin-induced (STZ) diabetic mouse ovarian tissues (n = 3). Diabetic mouse ovaries exhibited a relative decrease in sialylation, fucosylation and, to a lesser extent, branched N-linked glycan structures, as well as an increase in oligomannose structures on their proteins, compared with nondiabetic mouse ovaries. Changes in N-glycans occurred in the diabetic liver tissue but were more evident in diabetic ovarian tissue of the same mouse, suggesting an organ-specific effect of diabetes mellitus on protein glycosylation. Although at a very low amount, O-GalNAc glycans of mice ovaries were present as core type 1 and core type 2 glycans; with a relative increase in the NeuGc:NeuAc ratio as the most significant difference between control and diabetic ovarian tissues. STZ-treated mice also showed a trend towards an increase in TNF-α and IL1-B inflammatory cytokines, which have previously been shown to influence protein glycosylation.

Knockdown of FUT3 disrupts the proliferation, migration, tumorigenesis and TGF-β induced EMT in pancreatic cancer cells

Fucosyltransferases (FUTs) are critical for glycoproteins and glycolipid chains and serve an important role in the adhesive interaction between selectins and their ligands, which contribute to tumor cell spread and metastasis. While multiple cancer cell lines heavily express FUT3, the present study investigated the expression level of FUT3 in different human pancreatic cancer cell lines. Forced expression and knockdown of FUT3 in different pancreatic cancer cell line demonstrated that FUT3 is important in cell proliferation. Using wound healing and transwell assays, it was observed that the migratory ability was decreased in FUT3 downregulated Capan-1 cell line, compared with the normal Capan-1 cell line. Furthermore, it was demonstrated that the knockdown of FUT3 impaired the adhesion of Capan-1 with E-selectin and inhibited transforming growth factor (TGF)-β-induced epithelial-mesenchymal transition. These data suggest that the knockdown of FUT3 inhibits the tumorigenesis in vivo and FUT3 may be a promising target aiming at reducing the metastatic virulence of pancreatic cancer cells.

Triple-negative and HER2-overexpressing breast cancer cell sialylation impacts tumor microenvironment T-lymphocyte subset recruitment: a possible mechanism of tumor escape

Introduction

Breast cancers develop different patterns of sialylation to modulate their tumor-infiltrating lymphocyte (TIL) environment. We studied the relationship between α-2,6 sialyltransferases and the TIL in different breast cancer molecular subgroups.

Materials and methods

Immunohistochemical preparations were made from 39 luminal (LUM), 13 human epidermal growth factor receptor 2-overexpressing (HER2) and 47 triple-negative (TN) breast carcinomas. Targeted proteins included ST6Gal-I, ST6Gal-II, ST6GalNac-I, CD8, CD4 and granzyme-B in both cytotoxic T lymphocytes and NK lymphocytes (CTL/NK).

Results

CTL/NK populations were significantly more frequent in TN than LUM (P <0.001). TN showed a lower level of ST6Gal-I expression than LUM or HER2 (both P > 0.001). ST6GalNac-I expression was lower in LUM than in TN or HER2 (P = 0.002 and P = 0.02, respectively). In HER2, a significant association was found between a low level of ST6Gal-I expression and a high TIL level. In TN, a significant association was observed between a high level of ST6Gal-II expression and a high TIL level.

Conclusion

An increase in infiltrating lymphocytes could be influenced by low expression of ST6Gal-I in HER2 and by high expression of ST6Gal-II in TN breast cancers. Thus, targeting these sialylation pathways could modulate the levels of TIL.

Human disease glycomics: technology advances enabling protein glycosylation analysis - part 2

INTRODUCTION

The changes in glycan structures have been attributed to disease states for several decades. The surface glycosylation pattern is a signature of physiological state of a cell. In this review we provide a link between observed substructural glycan changes and a range of diseases. Areas covered: We highlight biologically relevant glycan substructure expression in cancer, inflammation, neuronal diseases and diabetes. Furthermore, the alterations in antibody glycosylation in a disease context are described. Expert commentary: Advances in technologies, as described in Part 1 of this review have now enabled the characterization of specific glycan structural markers of a range of disease states. The requirement of including glycomics in cross-disciplinary omics studies, such as genomics, proteomics, epigenomics, transcriptomics and metabolomics towards a systems glycobiology approach to understanding disease mechanisms and management are highlighted.

Analysis of sialyl-Lewis x on MUC5AC and MUC1 mucins in pancreatic cancer tissues

Pancreatic adenocarcinoma (PDAC) lacks efficient biomarkers. Mucins are glycoproteins that can carry aberrant glycosylation in cancer. Our objective was to identify cancer-related glycan epitopes on MUC1 and MUC5AC mucins in PDAC as potential biomarkers. We have analysed the tumour-associated carbohydrate antigens sialyl-Lewis x (SLe^x) and sialyl-Tn (STn) on MUC1 and MUC5AC in PDAC tissues. The selected cohort for this study consisted of twenty-one PDAC tissues positive for SLe^x antigen and three normal pancreas specimens as controls. STn expression was shown in 76% of the PDAC tissues. MUC1 and MUC5AC were detected in 90% of PDAC tissues. We performed in situ proximity ligation assay combining antibodies against mucins and glycan epitopes to identify specific mucin glycoforms. MUC1-SLe^x and MUC5AC-SLe^x were found in 68% and 84% respectively, of the mucin expressing PDAC tissues, while STn hardly colocalized with any of the evaluated mucins. Further analysis by Western blot of MUC5AC and SLe^x in eight PDAC tissue lysates showed that six out of eight cases were positive for both markers. Moreover, immunoprecipitation of MUC5AC from positive PDAC tissues and subsequent SLe^x immunodetection confirmed the presence of SLe^x on MUC5AC. Altogether, MUC5AC-SLe^x glycoform is present in PDAC and can be regarded as potential biomarker.

Hallmarks of glycosylation in cancer

Aberrant glycosylation plays a fundamental role in key pathological steps of tumour development and progression. Glycans have roles in cancer cell signalling, tumour cell dissociation and invasion, cell-matrix interactions, angiogenesis, metastasis and immune modulation. Aberrant glycosylation is often cited as a ‘hallmark of cancer’ but is notably absent from both the original hallmarks of cancer and from the next generation of emerging hallmarks. This review discusses how glycosylation is clearly an enabling characteristic that is causally associated with the acquisition of all the hallmark capabilities. Rather than aberrant glycosylation being itself a hallmark of cancer, another perspective is that glycans play a role in every recognised cancer hallmark.

c-Fos mediates α1, 2-fucosyltransferase 1 and Lewis y expression in response to TGF-β1 in ovarian cancer

FUT1 is a key rate-limiting enzyme in the synthesis of Lewis y, a membrane-associated carbohydrate antigen. The aberrant upregulation of FUT1 and Lewis y antigen is related to proliferation, invasion and prognosis in malignant epithelial tumors. A c-Fos/activator protein-1 (AP-1) binding site was found in the FUT1 promoter. However, the mechanisms of transcriptional regulation of FUT1 remain poorly understood. TGF-β1 is positively correlated to Lewis y. In the present study, we investigated the molecular mechanism of FUT1 gene expression in response to TGF-β1. We demonstrated that c-Fos was highly expressed in 77.50% of ovarian epithelial carcinoma cases and was significantly correlated with Lewis y. Using luciferase activity and chromatin immunoprecipitation (ChIP) assay, we further revealed that c-Fos interacted with the FUT1 promoter in ovarian cancer cells and transcriptional capacity of the heterodimer formed by c-Fos and c-Jun was stronger than that of the c-Fos or c-Jun homodimers. Then, we demonstrated that TGF-β1 induced dose-dependent c-Fos expression, which was involved in TGF-β1-induced ovarian cancer cell proliferation. In addition, inhibition of MAPK activation or TGF-β1 receptor by pharmacological agents prevented TGF-β1-induced c-Fos and Lewis y expression. Silencing of c-Fos prevented TGF-β1-induced Lewis y expression. Collectively, the results of these studies demonstrated that TGF-β1 regulated FUT1 and Lewis y expression by activating the MAPK/c-Fos pathway.

High expression of FUT3 is linked to poor prognosis in clear cell renal cell carcinoma

Background and Purpose

Some of the fucosylation catalyzed by fucosyltransferase-III mediates the epithelial-mesenchymal transition and enhances tumor cell-macrophage signaling, which promotes malignant transforming and immune evasion. The aim of the study was to investigate the association between the expression of fucosyltransferase-III and clinical outcomes of patients with clear-cell renal cell carcinoma after surgery.

Results

High fucosyltransferase-III expression was associated with a greater risk of recurrence (p = 0.002) and shortened overall survival (p < 0.001). We then established a prognostic nomogram including tumor size, pathologic T, N, M stage, coagulative necrosis, lymphovascular invasion and fucosyltransferase-III expression. Furthermore, the predictive accuracy of the Leibovich prognostic score was improved when fucosyltransferase-III expression was added (p = 0.009 for overall survival and p = 0.002 for recurrence-free survival).

Materials and Methods

We conducted a retrospective cohort study of 406 patients who underwent partial or radical nephrectomy between January 2008 and December 2009 in a single institute. Fucosyltransferase-III expression levels were evaluated by immunohistochemical staining in tumor tissues. Kaplan-Meier method was applied to compare survival curves. Cox regression models were fitted to analyze the effect of prognostic factors on recurrence-free and overall survival. Harrell’s concordance index and Akaike’s Information Criteria were calculated to assess predictive accuracy.

Conclusions

Fucosyltransferase-III is a predictive factor for poor overall survival and recurrence free survival in patients with ccRCC. The inhibitor of fucosyltransferase-III might be a potential therapeutic method for the disease.

IL-6 roles - Molecular pathway and clinical implication in pancreatic cancer - A systemic review

Pancreatic cancer has attracted a great deal of attention owing to the poor outcome, increasing prevalence in the last years and delay diagnosis. Known as a complex disease, it involves genetic mutations, changes in tumour microenvironment and inflammatory component dominated by interleukin-6 and its activated pathways, like Janus Kinase-Signal Transducer and Activator of Translation3, Mitogen Activated Protein Kinase and Androgen receptor. The pro-inflammatory cytokine, plays a central role in oncogenesis, cancer progression, invasiveness, microenvironment changes, treatment resistance, prognosis and associated co morbidities like cachexia and depression. Fulfilling these roles IL-6 requires special attention to understand its complexity in PC development.

The cytokine-cosmc signaling axis upregulates the tumor-associated carbohydrate antigen Tn

Tn antigen (GalNAc-α-O-Ser/Thr), a mucin-type O-linked glycan, is a well-established cell surface marker for tumors and its elevated levels have been correlated with cancer progression and prognosis. There are also reports that Tn is elevated in inflammatory tissues. However, the molecular mechanism for its elevated levels in cancer and inflammation is unclear. In the current studies, we have explored the possibility that cytokines may be one of the common regulatory molecules for elevated Tn levels in both cancer and inflammation. We showed that the Tn level is elevated by the conditioned media of HrasG12V-transformed-BEAS-2B cells. Similarly, the conditioned media obtained from LPS-stimulated monocytes also elevated Tn levels in primary human gingival fibroblasts, suggesting the involvement of cytokines and/or other soluble factors. Indeed, purified inflammatory cytokines such as TNF-α and IL-6 up-regulated Tn levels in gingival fibroblasts. Furthermore, TNF-α was shown to down-regulate the COSMC gene as evidenced by reduced levels of the COSMC mRNA and protein, as well as hypermethylation of the CpG islands of the COSMC gene promoter. Since Cosmc, a chaperone for T-synthase, is known to negatively regulate Tn levels, our results suggest elevated Tn levels in cancer and inflammation may be commonly regulated by the cytokine-Cosmc signaling axis.

Polyplex-mediated inhibition of chemokine receptor CXCR4 and chromatin-remodeling enzyme NCOA3 impedes pancreatic cancer progression and metastasis

Pancreatic cancer (PC) is one of the most aggressive malignancies due to intense desmoplasia, extreme hypoxia and inherent chemoresistance. Studies have implicated the expression of chemokine receptor CXCR4 and nuclear receptor co-activator-3 (NCOA3) in the development of desmoplasia and metastatic spread of PC. Using a series of polymeric CXCR4 antagonists (PCX), we optimized formulation of PCX/siNCOA3 polyplexes to simultaneously target CXCR4 and NCOA3 in PC. Cholesterol-modified PCX showed maximum CXCR4 antagonism, NCOA3 silencing and inhibition of PC cell migration in vitro. The optimized PCX/siNCOA3 polyplexes were used in evaluating antitumor and antimetastatic activity in orthotopic mouse model of metastatic PC. The polyplexes displayed significant inhibition of primary tumor growth, which was accompanied by a decrease in tumor necrosis and increased tumor perfusion. The polyplexes also showed significant antimetastatic effect and effective suppression of metastasis to distant organs. Overall, dual-function PCX/siNCOA3 polyplexes can effectively regulate tumor microenvironment to decrease progression and dissemination of PC.

GlycA, a novel proinflammatory glycoprotein biomarker, and high-sensitivity C-reactive protein are inversely associated with sodium intake after controlling for adiposity: the Prevention of Renal and Vascular End-Stage Disease study

BACKGROUND

The extent to which dietary sodium intake may confer alterations in the inflammatory status is unclear. GlycA is a novel proton nuclear magnetic resonance spectroscopy-measured biomarker of systemic inflammation, which is associated with the development of cardiovascular disease and diabetes.

OBJECTIVE

We determined associations of the inflammatory markers GlycA and high-sensitivity C-reactive protein (hsCRP) with 24-h sodium excretion.

DESIGN

A cross-sectional, population-based study was performed in 3935 subjects who were not using an antihypertensive medication, lipid-lowering drugs, or a glucose-lowering treatment. Urinary sodium excretion was calculated as the mean of two 24-h urine excretions. Linear regression models were used, with 24-h sodium excretion as an independent variable and GlycA or ln hsCRP as a dependent variable.

RESULTS

The mean ± SD sodium excretion was 143.0 ± 53.4 mmol/24 h. The GlycA concentration was 343.6 ± 58.7 μmol/L, and the geometric mean of the hsCRP concentration was 1.20 mg/L (95% CI: 1.16, 1.25 mg/L). In age- and sex-adjusted analyses, GlycA and ln hsCRP were not significantly associated with 24-h sodium excretion [B: 1.23 (95% CI: -0.67, 3.13; P = 0.21) and 0.03 (95% CI: -0.004, 0.07; P = 0.08), respectively, per 1-SD increase]. After additional adjustment for body mass index (BMI), both GlycA (B: -2.76; 95% CI: -4.65, -0.86; P = 0.004) and ln hsCRP (B: -0.07; 95% CI: -0.11, -0.04; P < 0.001) were inversely associated with 24-h sodium excretion. These associations were similar if adjustment was performed for waist circumference instead of BMI or if additional adjustment was performed for relevant clinical and laboratory variables and were particularly present in men.

CONCLUSIONS

The proinflammatory biomarkers GlycA and hsCRP are inversely related to higher 24-h sodium excretion when taking into account the variation in adiposity. These inverse relations remain present after taking into account other covariates.

Turning-Off Signaling by Siglecs, Selectins, and Galectins: Chemical Inhibition of Glycan-Dependent Interactions in Cancer

Aberrant glycosylation, a common feature associated with malignancy, has been implicated in important events during cancer progression. Our understanding of the role of glycans in cancer has grown exponentially in the last few years, concurrent with important advances in glycomics and glycoproteomic technologies, paving the way for the validation of a number of glycan structures as potential glycobiomarkers. However, the molecular bases underlying cancer-associated glycan modifications are still far from understood. Glycans exhibit a natural heterogeneity, crucial for their diverse functional roles as specific carriers of biologically relevant information. This information is decoded by families of proteins named lectins, including sialic acid-binding immunoglobulin (Ig)-like lectins (siglecs), C-type lectin receptors (CLRs), and galectins. Siglecs are primarily expressed on the surface of immune cells and differentially control innate and adaptive immune responses. Among CLRs, selectins are a family of cell adhesion molecules that mediate interactions between cancer cells and platelets, leukocytes, and endothelial cells, thus facilitating tumor cell invasion and metastasis. Galectins, a family of soluble proteins that bind β-galactoside-containing glycans, have been implicated in diverse events associated with cancer biology such as apoptosis, homotypic cell aggregation, angiogenesis, cell migration, and tumor-immune escape. Consequently, individual members of these lectin families have become promising targets for the design of novel anticancer therapies. During the past decade, a number of inhibitors of lectin–glycan interactions have been developed including small-molecule inhibitors, multivalent saccharide ligands, and more recently peptides and peptidomimetics have offered alternatives for tackling tumor progression. In this article, we review the current status of the discovery and development of chemical lectin inhibitors and discuss novel strategies to limit cancer progression by targeting lectin–glycan interactions.

Terminal Galactosylation and Sialylation Switching on Membrane Glycoproteins upon TNF-Alpha-Induced Insulin Resistance in Adipocytes

Insulin resistance (IR) is a complex pathophysiological state that arises from both environmental and genetic perturbations and leads to a variety of diseases, including type-2 diabetes (T2D). Obesity is associated with enhanced adipose tissue inflammation, which may play a role in disease progression. Inflammation modulates protein glycosylation in a variety of cell types, and this has been associated with biological dysregulation. Here, we have examined the effects of an inflammatory insult on protein glycosylation in adipocytes. We performed quantitative N-glycome profiling of membrane proteins derived from mouse 3T3-L1 adipocytes that had been incubated with or without the proinflammatory cytokine TNF-alpha to induce IR. We identified the regulation of specific terminal N-glycan epitopes, including an increase in terminal di-galactose- and a decrease in biantennary alpha-2,3-sialoglycans. The altered N-glycosylation of TNF-alpha-treated adipocytes correlated with the regulation of specific glycosyltransferases, including the up-regulation of B4GalT5 and Ggta1 galactosyltransferases and down-regulation of ST3Gal6 sialyltransferase. Knockdown of B4GalT5 down-regulated the terminal di-galactose N-glycans, confirming the involvement of this enzyme in the TNF-alpha-regulated N-glycome. SILAC-based quantitative glycoproteomics of enriched N-glycopeptides with and without deglycosylation were used to identify the protein and glycosylation sites modified with these regulated N-glycans. The combined proteome and glycoproteome workflow provided a relative quantification of changes in protein abundance versus N-glycosylation occupancy versus site-specific N-glycans on a proteome-wide level. This revealed the modulation of N-glycosylation on specific proteins in IR, including those previously associated with insulin-stimulated GLUT4 trafficking to the plasma membrane.

Higher circulating GlycA, a pro-inflammatory glycoprotein biomarker, relates to lipoprotein-associated phospholipase A2 mass in nondiabetic subjects but not in diabetic or metabolic syndrome subjects

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a cardiovascular risk marker, which is in part complexed to low-density lipoproteins, where it exerts pro-inflammatory properties. GlycA is a pro-inflammatory proton nuclear magnetic resonance spectroscopy biomarker whose signal originates from a subset of N-acetylglucosamine residues on the most abundant glycosylated acute-phase proteins.

OBJECTIVE

We compared plasma GlycA and Lp-PLA2 mass between subjects without type 2 diabetes mellitus (T2DM) or the metabolic syndrome (MetS) and subjects with T2DM and/or MetS. We also tested the relationship of GlycA with Lp-PLA2 in each group.

METHODS

Plasma GlycA, Lp-PLA2 mass, high-sensitivity C-reactivity protein (hsCRP) and lipids were measured in 40 subjects with neither T2DM nor MetS (group 1) and in 58 subjects with T2DM and/or MetS (group 2).

RESULTS

GlycA and hsCRP were higher (P < .01 for each), whereas Lp-PLA2 was lower in group 2 vs group 1 (P < .001). GlycA was positively related to hsCRP in each group (P < .001). In contrast, GlycA was correlated positively with Lp-PLA2 in group 1 (r = 0.384, P = .015), but not in group 2 (r = 0.045; P = .74; interaction term for difference: P = .059). Although Lp-PLA2 was correlated positively with non-high-density lipoprotein cholesterol and low-density lipoprotein cholesterol in each group (P ≤ .02), its inverse relationship with high-density lipoprotein cholesterol in group 1 (r = -0.381, P = .013) was absent in group 2 (r = -0.101, P = .42).

CONCLUSIONS

A pro-inflammatory glycoprotein biomarker, GlycA, is higher in subjects with either T2DM, MetS, or both. The normally present positive relationship of GlycA with Lp-PLA2 is blunted in subjects with T2DM and/or MetS.