Lewis x is highly expressed in normal tissues: a comparative immunohistochemical study and literature revision

Characterization of N-glycome profile in mouse brain tissue regions by MALDI-TOF/MS

Glycosylation is one of the most common types of post-translational modifications in mammals. It is well known that N-glycans play a key role in cell adhesion, differentiation, synapsis, and myelination during the development of the mammalian central nervous system (CNS). Neuropathological symptoms (such as epilepsy and Alzheimer's disease) are usually accompanied by N-glycosylation changes. In this study, we extracted N-glycan chains from eight regions of the mouse brain, and combined high-throughput, high-resolution matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) with the Fmoc N-hydroxysuccinimide ester (Fmoc-OSU) derivatization method to improve the sensitivity of glycan detection to characterize the total N-glycans in the mouse brain. A total of 96 N-glycan moieties were detected. An exhaustive examination of the relative abundance of N-glycans, coupled with a comparative analysis of differences, has uncovered discernible variations of statistical significance, including high mannose, fucosylated, sialylated, and galactosylated N-glycans. According to our investigations, a thorough and regionally specific cartography of glycans within the brain can facilitate the investigation of glycan-mediated mechanisms related to both the developmental trajectory and functional output of the brain. Additionally, this approach may serve as a basis for identifying potential biomarkers that are relevant to various brain-associated pathologies.

SSEA-1 Correlates With the Invasive Phenotype in Breast Cancer

The glycan moiety Lewis X (LeX) has been implicated in defining progenitor cells as well as playing a role in the progression of solid tumors, including breast cancer. Here, we used the original stage-specific embryonic antigen-1 (SSEA-1) antibody, MC-480, targeting the LeX motif to examine the expression pattern of this marker within the context of a differentiation hierarchy as well as functional properties of breast cancer cells. Immunohistochemical staining revealed the presence of SSEA-1 in a progenitor zone in the normal breast gland. In breast cancer, 81 of 220 carcinomas (37%) were positive for SSEA-1 and a distinct pattern could be correlated to major subtypes. Specifically, estrogen receptor alpha (ERα)-negative tumors showed a higher frequency of SSEA-1 expression compared to ERα-positive tumors, which are generally considered more differentiated (56% vs 29%, p<0.005). Functional assays performed on two representative breast cancer cell lines demonstrated that SSEA-1-expressing cells exhibited cancer stem cell properties as well as having more invasive potential, regardless of ERα status. A potential role of SSEA-1 in metastasis was confirmed by pairwise staining of primary- and corresponding lymph node tumors. Altogether, our data suggest that expression of SSEA-1 in breast cancer contributes to the malignant phenotype.

Neonatal subchronic toxicity and in vitro genotoxicity studies of the human-identical milk oligosaccharide 3-fucosyllactose

Human milk oligosaccharides, such as 3-fucosyllactose (3-FL), are bioactive components of breast milk associated with benefits for infant growth and development. Structurally identical compounds (human-identical milk oligosaccharides - HiMOs) can be produced using microbial fermentation, allowing their use in infant formula to increase its similarity with human milk. Toxicological studies are required to demonstrate safety of HiMOs and that of any impurities potentially carried over from the manufacturing process. Biotechnologically produced 3-FL was tested for potential genotoxicity (bacterial reverse mutation test and in vitro mammalian micronucleus test) and subchronic toxicity (90-day study with neonatal rats). In the 90-day study, 3-FL was administered by gavage to rats once daily from Day 7 of age, at doses up to 4000 mg/kg body weight (bw)/day (the maximum feasible dose), followed by a 4-week recovery period. Reference controls received 4000 mg/kg bw/day of oligofructose, an ingredient permitted for use in infant formula. Results for the genotoxicity studies were negative. In the 90-day study, there were no adverse effects of 3-FL on any of the parameters measured; thus, the no-observed-adverse-effect level was 4000 mg/kg bw/day (the highest dose tested). These results support the safety of biotechnologically produced 3-FL for use in infant formula and other foods.

An Introduction to the Relationship Between Lewis x and Malignancy Mainly Related to Breast Cancer and Head Neck Squamous Cell Carcinoma (HNSCC)

Lewis x functions as an adhesion molecule in glycolipids and glycoproteins since it mediates homophilic and heterophilic attachment of normal and tumoral cells. During malignancy, altered glycosylation is a frequent event; accumulating data support the expression of Lewis x in tumors although controversial results have been described including its relationship with patient survival. This report has been developed as an introduction to the relationship between Lewis x expression and breast cancer and head and neck squamous cell carcinoma (HNSCC). Results obtained in our laboratory are presented in the context of the literature.

Unique Tropism and Entry Mechanism of Mumps Virus

Mumps virus (MuV) is an important human pathogen that causes parotitis, orchitis, oophoritis, meningitis, encephalitis, and sensorineural hearing loss. Although mumps is a vaccine-preventable disease, sporadic outbreaks have occurred worldwide, even in highly vaccinated populations. MuV not only causes systemic infection but also has a unique tropism to glandular tissues and the central nervous system. In general, tropism can be defined by multiple factors in the viral life cycle, including its entry, interaction with host factors, and host-cell immune responses. Although the underlying mechanisms of MuV tropism remain to be fully understood, recent studies on virus-host interactions have provided insights into viral pathogenesis. This review was aimed at summarizing the entry process of MuV by focusing on the glycan receptors, particularly the recently identified receptors with a trisaccharide core motif, and their interactions with the viral attachment proteins. Here, we describe the receptor structures, their distribution in the human body, and the recently identified host factors for MuV and analyze their relationship with MuV tropism.

Beyond Colonoscopy: Exploring New Cell Surface Biomarkers for Detection of Early, Heterogenous Colorectal Lesions

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths among both men and women in the United States. Early detection and surgical removal of high-risk lesions in the colon can prevent disease from developing and spreading. Despite implementation of programs aimed at early detection, screening colonoscopies fail to detect a fraction of potentially aggressive colorectal lesions because of their location or nonobvious morphology. Optical colonoscopies, while highly effective, rely on direct visualization to detect changes on the surface mucosa that are consistent with dysplasia. Recent advances in endoscopy techniques and molecular imaging permit microscale visualization of the colonic mucosa. These technologies can be combined with various molecular probes that recognize and target heterogenous lesion surfaces to achieve early, real-time, and potentially non-invasive, detection of pre-cancerous lesions. The primary goal of this review is to contextualize existing and emergent CRC surface biomarkers and assess each’s potential as a candidate marker for early marker-based detection of CRC lesions. CRC markers that we include were stratified by the level of support gleaned from peer-reviewed publications, abstracts, and databases of both CRC and other cancers. The selected biomarkers, accessible on the cell surface and preferably on the luminal surface of the colon tissue, are organized into three categories: (1) established biomarkers (those with considerable data and high confidence), (2) emerging biomarkers (those with increasing research interest but with less supporting data), and (3) novel candidates (those with very recent data, and/or supportive evidence from other tissue systems). We also present an overview of recent advances in imaging techniques useful for visual detection of surface biomarkers, and discuss the ease with which these methods can be combined with microscopic visualization.

High-throughput surface marker screen on primary human breast tissues reveals further cellular heterogeneity

BACKGROUND

Normal human breast tissues are a heterogeneous mix of epithelial and stromal subtypes in different cell states. Delineating the spectrum of cellular heterogeneity will provide new insights into normal cellular properties within the breast tissue that might become dysregulated in the initial stages of cancer. Investigation of surface marker expression provides a valuable approach to resolve complex cell populations. However, the majority of cell surface maker expression of primary breast cells have not been investigated.

METHODS

To determine the differences in expression of a range of uninvestigated cell surface markers between the normal breast cell subpopulations, primary human breast cells were analysed using high-throughput flow cytometry for the expression of 242 cell surface proteins in conjunction with EpCAM/CD49f staining.

RESULTS

We identified 35 surface marker proteins expressed on normal breast epithelial and/or stromal subpopulations that were previously unreported. We also show multiple markers were equally expressed in all cell populations (e.g. CD9, CD59, CD164) while other surface markers were confirmed to be enriched in different cell lineages: CD24, CD227 and CD340 in the luminal compartment, CD10 and CD90 in the basal population, and CD34 and CD140b on stromal cells.

CONCLUSIONS

Our dataset of CD marker expression in the normal breast provides better definition for breast cellular heterogeneity.

Regulation of mucin 1 expression and its relationship with oral diseases

OBJECTIVE

The aim of this study is to describe the polymorphic mucin 1 (MUC1), and to provide an overview of the known complex and multiple functions of MUC1 in normal oral mucosa and oral mucosal lesions in compromised situations as well as exploring the challenges associated with the heterogeneous nature of MUC1. We will review the current knowledge and provide insights into the future management possibilities of using MUC1 as a therapeutic agent.

METHODS

A literature search of the electronic databases included MEDLINE (1966 -December 2019) and hand searches of cross-references were undertaken using terms related to mucins, MUC1.

RESULTS

MUC1 is a large transmembrane glycoprotein expressed on the apical surface of most of epithelial cell surfaces. Not only is it involved in lubrication, cell surface hydration, and protection against degrading enzymes, MUC1 also promotes abnormal cellular signalling, angiogenesis, anti-adhesion and tumorigenesis. Aberrant glycosylation, overexpression, loss of apical constraint are characteristics of the transformation of a normal cell to a cancerous cell. This review summarizes studies of MUC1 expression and function with a special emphasis on oral epithelial cells in normal and abnormal conditions. In addition, current knowledge of MUC1 and unexplored areas of MUC1 are presented.

CONCLUSION

MUC1 is an archetypical transmembrane protein, the presence of MUC1 in ectopic regions may lead to dysregulation of certain enzymes and activation of various pathways, favouring the development of inflammatory responses and tumour formation. This review examines the potential of MUC1 in the development of future therapeutics.

Anti-Glycan Autoantibodies Induced by Helicobacter pylori as a Potential Risk Factor for Myocardial Infarction

A number of epidemiological studies have evaluated the potential association between H. pylori and cardiovascular disease, but with contrasting results. We have previously shown that Helicobacter pylori infection is able to induce in mice and humans autoantibodies cross-reacting with histo–blood group Lewis antigens, expressed in different organs and in plasma glycoproteins and glycolipids. The aim of this study was to assess whether immunization of animals with H. pylori might induce myocardial histopathological changes. We have retrospectively examined, in detail, the histology of archived organs from mice and rabbits immunized with H. pylori in our previous studies. Human sera and cross-reacting monoclonal antibodies were also tested against bacterial preparations and tissue sections. Areas of myocardial necrosis, associated with coronary thrombotic occlusion, were found in 5 of 20 mice and 2 of 5 rabbits previously immunized with suspensions of H. pylori. No similar lesions were found in control animals, suggesting a causal link with H. pylori immunization. The animals bearing myocardial lesions had not been infected but only immunized months earlier with parenteral injections of dead H. pylori cells. This strongly suggests that immunization, by itself, might play a causative role. We propose that the cross-reactive autoimmune response induced by H. pylori could promote thrombotic occlusion through direct endothelial damage or by perturbing the coagulation process.

Breast cancer cutaneous metastases are associated to uMUC1 and sialyl Lewis x and to highly malignant primary tumors

Breast cancer spreading to different organs have been related to different molecules and mechanisms, but cutaneous metastasis remains unexplored. Increasing evidence showed that MUC1 and some of its carbohydrate associated antigens may be implicated in breast cancer metastasis. In this study we analyzed these tumor markers in order to identify breast cancer cutaneous metastatic profiles. A cohort of 26 primary tumors from breast cancer patients with cutaneous metastases were included; also, cutaneous and lymphatic node metastatic samples and primary tumors from breast cancer patients without metastases were analysed. Immunohistochemical (IHC) studies demonstrated that both underglycosylated MUC1 (uMUC1) and sialyl Lewis x (sLex) to be positively associated with cutaneous metastatic primary tumors (p < 0.05). Notably, a high percentage of tumors with cutaneous metastases were characterized as triple negative and Her2+ tumors (37.5 % and 29 %, respectively). Some discordant results were found between primary tumors and their matched cutaneous metastases. To determine if MUC1 variants may be carriers of carbohydrate antigens, subcellular fractions from a cutaneous metastatic lesion were obtained, immunoprecipitated and analyzed by Western blot. We found that the isolated uMUC1 with a molecular weight of>200 kDa was also the site for binding of anti-sLex MAb; in coincidence, a high correlation of positive IHC expression of both markers was observed. Our findings confirm that breast cancer cutaneous metastases were associated to highly malignant primary tumors and sustain the hypothesis that u-MUC1 and sLe x may drive breast cancer cutaneous metastases.

The "less-is-more" in therapeutic antibodies: Afucosylated anti-cancer antibodies with enhanced antibody-dependent cellular cytotoxicity

Therapeutic monoclonal antibodies are the fastest growing class of biological therapeutics for the treatment of various cancers and inflammatory disorders. In cancer immunotherapy, some IgG1 antibodies rely on the Fc-mediated immune effector function, antibody-dependent cellular cytotoxicity (ADCC), as the major mode of action to deplete tumor cells. It is well-known that this effector function is modulated by the N-linked glycosylation in the Fc region of the antibody. In particular, absence of core fucose on the Fc N-glycan has been shown to increase IgG1 Fc binding affinity to the FcγRIIIa present on immune effector cells such as natural killer cells and lead to enhanced ADCC activity. As such, various strategies have focused on producing afucosylated antibodies to improve therapeutic efficacy. This review discusses the relevance of antibody core fucosylation to ADCC, different strategies to produce afucosylated antibodies, and an update of afucosylated antibody drugs currently undergoing clinical trials as well as those that have been approved.

Tumor recognition of peanut agglutinin-immobilized fluorescent nanospheres in biopsied human tissues

We are investigating an imaging agent for early detection of colorectal cancer. The agent, named the nanobeacon, is coumarin 6-encapsulated polystyrene nanospheres whose surfaces are covered with poly(N-vinylacetamide) and peanut agglutinin that reduces non-specific interactions with the normal mucosa and exhibits high affinity for terminal sugars of the Thomsen-Friedenreich antigen, which is expressed cancer-specifically on the mucosa, respectively. We expect that cancer can be diagnosed by detecting illumination of intracolonically administered nanobeacon on the mucosal surface. In the present study, biopsied human tissues were used to evaluate the potential use of the nanobeacon in the clinic. Prior to the clinical study, diagnostic capabilities of the nanobeacon for detection of colorectal cancer were validated using 20 production batches whose characteristics were fine-tuned chemically for the purpose. Ex vivo imaging studies on 66 normal and 69 cancer tissues removed from the colons of normal and orthotopic mouse models of human colorectal cancer, respectively, demonstrated that the nanobeacon detected colorectal cancer with excellent capabilities whose rates of true and false positives were 91% and 5%, respectively. In the clinical study, normal and tumor tissues on the large intestinal mucosa were biopsied endoscopically from 11 patients with colorectal tumors. Histological evaluation revealed that 9 patients suffered from cancer and the rest had adenoma. Mean fluorescence intensities of tumor tissues treated with the nanobeacon were significantly higher than those of the corresponding normal tissues. Correlation of magnitude relation of the intensity in individuals was observed in cancer patients with a high probability (89%); however, the probability reduced to 50% in adenoma patients. There was a reasonable likelihood for diagnosis of colorectal cancer by the nanobeacon applied to the mucosa of the large intestine.

Evidence for a carbohydrate-binding module (CBM) of Tannerella forsythia NanH sialidase, key to interactions at the host–pathogen interface

Bacterial sialidases cleave terminal sialic acid from a variety of host glycoproteins, and contribute to survival and growth of many human-dwelling bacterial species, including various pathogens. Tannerella forsythia, an oral, Gram-negative, fastidious anaerobe, is a key organism in periodontal disease and possesses a dedicated sialic acid utilisation and scavenging (nan) operon, including NanH sialidase. Here, we describe biochemical characterisation of recombinant NanH, including its action on host-relevant sialoglycans such as sialyl Lewis A and sialyl Lewis X (SLeA/X), and on human cell-attached sialic acids directly, uncovering that it is a highly active broad specificity sialidase. Furthermore, the N-terminal domain of NanH was hypothesised and proved to be capable of binding to a range of sialoglycans and non-sialylated derivatives with Kd in the micromolar range, as determined by steady-state tryptophan fluorescence spectroscopy, but it has no catalytic activity in isolation from the active site. We consider this domain to represent the founding member of a novel subfamily of carbohydrate-binding module (CBM), involved in glycosidase-ligand binding. In addition, we created a catalytically inactive version of the NanH enzyme (FRIP → YMAP) that retained its ability to bind sialic acid-containing ligands and revealed for the first time that binding activity of a CBM is enhanced by association with the catalytic domain. Finally, we investigated the importance of Lewis-type sialoglycans on T. forsythia–host interactions, showing that nanomolar amounts of SLeA/X were capable of reducing invasion of oral epithelial cells by T. forsythia, suggesting that these are key ligands for bacterial–cellular interactions during periodontal disease.

Lewis x Antigen is Associated to Head and Neck Squamous Cell Carcinoma Survival

Head and neck squamous cell carcinoma (HNSCC) is an aggressive disease with poor prognosis without appropriate prognostic markers. Previous research shows that Lewis antigens have been involved in carcinoma dissemination and patients´ survival. Fucosyl and sialyltransferases are the enzymes implicated in the Lewis antigens synthesis. The purpose of this study was to evaluate the prognostic utility of Lewis antigens in HNSCC. We conducted a prospective research including histological samples from 79 patients with primary HNSCC. Lewis x and sialyl Lewis x expression were detected by immunohistochemistry; patient's data, progression free, and overall survival were documented. A statistical correlation study of antigenic expression and patients´ histopathological variables was performed. Cox regression models with internal validation procedures were employed to analyze survival data. By immunohistochemistry, Lewis x was detected in 34/79 (43%) tumor samples, while sialyl Lewis x only in 11/79 (14%). Lewis x expression showed a positive correlation with tumor differentiation and a better overall survival for Lewis x + patients was detected. Moreover, multivariate Cox's regression analysis showed that Lewis x is an independent predictor of better overall survival. The in silico analysis supported the presence of deregulated fucosyl (FUT4) and sialyltransferase (ST3GAL4) in the Lewis synthetic pathway related to patient survival. These results suggest that Lewis x expression is associated with a better outcome in patients with HNSCC.

Glycosyltransferases involved in the synthesis of MUC-associated metastasis-promoting selectin ligands

The sialyl Lewis a and x (sLe(a/x)) antigens frequently displayed on the surface of tumor cells are involved in metastasis. Their synthesis has been attributed to altered expression of selective glycosyltransferases. Identification of these glycosyltransferases and the glycoproteins that carry these carbohydrate antigens should help advance our understanding of selectin-mediated cancer metastasis. In this study, quantitative real-time polymerase chain reaction analysis coupled with in situ proximity ligation assay and small interference RNA treatment shows involvement of β3galactosyltransferase-V in the synthesis of MUC16-associated sLe(a) in H292 cells. Also, α3fucosyltransferase-V, which is absent in BEAS-2B human immortalized bronchial epithelial cells and A549 lung carcinoma cells, participates in the synthesis of MUC1-associated sLe(x) in CFT1 human immortalized bronchial epithelial cells and H292 lung carcinoma cells. Neither selectin ligand is found on MUC1 in BEAS-2B and A549 cells. Knockdown of either enzyme suppresses migration, and selectin tethering and rolling properties of H292 cells under dynamic flow as determined by wound healing and parallel plate flow chamber assays, respectively. These results provide insights into how the synthesis of mucin-associated selectin ligands and the metastatic properties of cancer cells can be regulated by selective glycosyltransferases that work on mucins. They may help develop novel anticancer drugs.

Anti-influenza neuraminidase inhibitor oseltamivir phosphate induces canine mammary cancer cell aggressiveness

Oseltamivir phosphate is a widely used anti-influenza sialidase inhibitor. Sialylation, governed by sialyltransferases and sialidases, is strongly implicated in the oncogenesis and progression of breast cancer. In this study we evaluated the biological behavior of canine mammary tumor cells upon oseltamivir phosphate treatment (a sialidase inhibitor) in vitro and in vivo. Our in vitro results showed that oseltamivir phosphate impairs sialidase activity leading to increased sialylation in CMA07 and CMT-U27 canine mammary cancer cells. Surprisingly, oseltamivir phosphate stimulated, CMT-U27 cell migration and invasion capacity in vitro, in a dose-dependent manner. CMT-U27 tumors xenograft of oseltamivir phosphate-treated nude mice showed increased sialylation, namely α2,6 terminal structures and SLe(x) expression. Remarkably, a trend towards increased lung metastases was observed in oseltamivir phosphate-treated nude mice. Taken together, our findings revealed that oseltamivir impairs canine mammary cancer cell sialidase activity, altering the sialylation pattern of canine mammary tumors, and leading, surprisingly, to in vitro and in vivo increased mammary tumor aggressiveness.

Structural and functional characterization of NanU, a novel high-affinity sialic acid-inducible binding protein of oral and gut-dwelling Bacteroidetes species

Many human-dwelling bacteria acquire sialic acid for growth or surface display. We identified previously a sialic acid utilization operon in Tannerella forsythia that includes a novel outer membrane sialic acid-transport system (NanOU), where NanO (neuraminate outer membrane permease) is a putative TonB-dependent receptor and NanU (extracellular neuraminate uptake protein) is a predicted SusD family protein. Using heterologous complementation of nanOU genes into an Escherichia coli strain devoid of outer membrane sialic acid permeases, we show that the nanOU system from the gut bacterium Bacteroides fragilis is functional and demonstrate its dependence on TonB for function. We also show that nanU is required for maximal function of the transport system and that it is expressed in a sialic acid-responsive manner. We also show its cellular localization to the outer membrane using fractionation and immunofluorescence experiments. Ligand-binding studies revealed high-affinity binding of sialic acid to NanU (Kd ~400 nM) from two Bacteroidetes species as well as binding of a range of sialic acid analogues. Determination of the crystal structure of NanU revealed a monomeric SusD-like structure containing a novel motif characterized by an extended kinked helix that might determine sugar-binding specificity. The results of the present study characterize the first bacterial extracellular sialic acid-binding protein and define a sialic acid-specific PUL (polysaccharide utilization locus).

Regulation of the metastatic cell phenotype by sialylated glycans

Tumor cells exhibit striking changes in cell surface glycosylation as a consequence of dysregulated glycosyltransferases and glycosidases. In particular, an increase in the expression of certain sialylated glycans is a prominent feature of many transformed cells. Altered sialylation has long been associated with metastatic cell behaviors including invasion and enhanced cell survival; however, there is limited information regarding the molecular details of how distinct sialylated structures or sialylated carrier proteins regulate cell signaling to control responses such as adhesion/migration or resistance to specific apoptotic pathways. The goal of this review is to highlight selected examples of sialylated glycans for which there is some knowledge of molecular mechanisms linking aberrant sialylation to critical processes involved in metastasis.

Vibrio cholerae cytolysin recognizes the heptasaccharide core of complex N-glycans with nanomolar affinity

Pathogens selectively target host cells using adhesion molecules and secreted virulence factors that may utilize protein, lipid, or carbohydrate ligands on the cell surface. The human intestinal pathogen Vibrio cholerae secretes a pore-forming toxin, V.cholerae cytolysin (VCC), which contains two domains that are structurally similar to known carbohydrate-binding proteins. These tandem domains are attached to the carboxy-terminus of the cytolytic domain and contain a β-trefoil fold and a β-prism fold. VCC has been shown to bind glycosylated proteins, and removal of the β-prism domain leads to a large decrease in lytic activity against rabbit erythrocytes. Despite these clues, the identity of the glycan receptors of VCC and the role of glycan binding in toxin activity remain unknown. To better understand this specificity, we used a combination of structural and functional approaches to characterize the carbohydrate-binding activity of the VCC toxin. We first probed the monosaccharide-binding activity of VCC and demonstrated that the toxin exhibits millimolar affinity for aldohexoses. To understand this specificity, we solved the crystal structure of the VCC β-prism domain bound to methyl-α-mannose. Next, we utilized a mammalian glycan screen to determine that the β-prism domain preferentially binds complex N-glycans with a heptasaccharide GlcNAc(4)Man(3) core (NGA2). Fluorescence anisotropy and surface plasmon resonance indicated an approximately 100-nM affinity of the β-prism domain for the heptasaccharide core. Our results suggest that carbohydrate-binding domains on the VCC toxin facilitate high-affinity targeting of mammalian cell membranes, which may contribute to the ability of VCC to lyse cells at picomolar concentrations.

Expression of the carcinoma markers: the sialylated Lewis A and X carbohydrate antigens in normal laryngeal surface epithelium and submucosal glands from old humans

Aberrant surface expression of the carbohydrate ABH and Lewis antigens are often used as markers for the diagnosis of cancer, but while the distribution of these histo-blood group antigens is relatively well-described in tissues and organs from young and middle-aged humans little is known of their expression in old age. The objective for this study was to estimate if the Lewis A and X antigens together with their sialylated modifications, are expressed in sections of normal laryngeal tissue from old humans. Antibodies directed against the tumor markers Sialyl Lewis A and Sialyl Lewis X showed positive reaction in the surface epithelia from normal larynx autopsies obtained from people aged 77-90 years. The sialylated and non-sialylated Lewis A antigens were more frequently expressed in the pseudostratified epithelium than in squamous surface epithelium. Both the sialylated and the non-sialylated carbohydrates were stained in the submucosal glands in all the autopsies. In conclusion, visualization of Lewis tumor markers in the larynx should be interpreted with great care, as they may be present in normal laryngeal epithelial cells from old humans.

Synthesis of 4" manipulated Lewis X trisaccharide analogues

Three analogues of the Le^x trisaccharide antigen (β-D-Galp(1→4)[α-L-Fucp(1→3)]-D-GlcNAcp) in which the galactosyl residue is modified at O-4 as a methyloxy, deoxychloro or deoxyfluoro, were synthesized. We first report the preparation of the modified 4-OMe, 4-Cl and 4-F trichloroacetimidate galactosyl donors and then report their use in the glycosylation of an N-acetylglucosamine glycosyl acceptor. Thus, we observed that the reactivity of these donors towards the BF₃·OEt₂-promoted glycosylation at O-4 of the N-acetylglucosamine glycosyl acceptors followed the ranking 4-F > 4-OAc ≈ 4-OMe > 4-Cl. The resulting disaccharides were deprotected at O-3 of the glucosamine residue and fucosylated, giving access to the desired protected Le^x analogues. One-step global deprotection (Na/NH₃) of the protected 4”-methoxy analogue, and two-step deprotections (removal of a p-methoxybenzyl with DDQ, then Zemplén deacylation) of the 4”-deoxychloro and 4”-deoxyfluoro protected Le^x analogues gave the desired compounds in good yields.

Tumour-associated carbohydrate antigens in breast cancer

Glycosylation changes that occur in cancer often lead to the expression of tumour-associated carbohydrate antigens. In breast cancer, these antigens are usually associated with a poor prognosis and a reduced overall survival. Cellular models have shown the implication of these antigens in cell adhesion, migration, proliferation and tumour growth. The present review summarizes our current knowledge of glycosylation changes (structures, biosynthesis and occurrence) in breast cancer cell lines and primary tumours, and the consequences on disease progression and aggressiveness. The therapeutic strategies attempted to target tumour-associated carbohydrate antigens in breast cancer are also discussed.

Comparative immunohistochemical study of MUC1 and carbohydrate antigens in breast benign disease and normal mammary gland

The aim was to compare the expression of MUC1 and carbohydrate antigens in 124 tissue samples; 42 fibroadenoma (FA), 23 nonproliferative benign diseases (NPF), 25 usual epithelial hyperplasia (UEH), 7 atypical ductal hyperplasia (ADH), and 27 breast normal tissues. An immunohistochemical approach was adopted, using the following antibodies: reactive with MUC1 variable number of tandem repeats (C595, HMFG2, and SM3 monoclonal antibodies), anti-MUC1-cytoplasmic tail polyclonal antibody (CT33), and anti-carbohydrate antigens (sialyl Lewis x, Lewis x, Lewis y, Tn, and Thomsen-Friedenreich epitopes). Positive area of reaction, intensity, and pattern of expression were considered. A reactivity index was calculated as intensity (I) x 100+percentage of positive area (A). Statistical analysis comprised frequency analysis, P < 0.05, analysis of variance, and multiple correlation with principal component analysis. All samples expressed MUC1, detected by at least one anti-MUC1 antibody whereas Lewis x was the carbohydrate antigen most frequently found in all groups whereas variable number of tandem repeats MUC1 and Lewis x showed the highest correlation: 93% of normal samples, 62.5% of NPF, 87% of FA, 85% of UEH, and finally 80% of ADH. Although principal component analysis using reactivity indexes explained only 39% of data variability, normal samples appeared grouped and separated from benign breast diseases, which remained spread. Thomsen-Friedenreich was the only antigen that showed an increased tendency for positive expression and intensity from NPF through FA, UEH to ADH, whereas it was not detected in normals. With respect to the pattern of expression, an apical pattern was predominantly found in all the groups.

Vaccine against MUC1 antigen expressed in inflammatory bowel disease and cancer lessens colonic inflammation and prevents progression to colitis-associated colon cancer

Association of chronic inflammation with an increased risk of cancer is well established, but the contributions of innate versus adaptive immunity are not fully delineated. There has furthermore been little consideration of the role played by chronic inflammation-associated antigens, including cancer antigens, and the possibility of using them as vaccines to lower the cancer risk. We studied the human tumor antigen MUC1 which is abnormally expressed in colon cancers and also in inflammatory bowel disease (IBD) that gives rise to colitis-associated colon cancer (CACC). Using our new mouse model of MUC1(+) IBD that progresses to CACC, interleukin-10 knockout mice crossed with MUC1 transgenic mice, we show that vaccination against MUC1 delays IBD and prevents progression to CACC. One mechanism is the induction of MUC1-specific adaptive immunity (anti-MUC1 IgG and anti-MUC1 CTL), which seems to eliminate abnormal MUC1(+) cells in IBD colons. The other mechanism is the change in the local and the systemic microenvironments. Compared with IBD in vaccinated mice, IBD in control mice is dominated by larger numbers of neutrophils in the colon and myeloid-derived suppressor cells in the spleen, which can compromise adaptive immunity and facilitate tumor growth. This suggests that the tumor-promoting microenvironment of chronic inflammation can be converted to a tumor-inhibiting environment by increasing adaptive immunity against a disease-associated antigen.

The membrane mucin MUC4 is elevated in breast tumor lymph node metastases relative to matched primary tumors and confers aggressive properties to breast cancer cells

Introduction

Previous studies indicate that overexpression of the membrane-associated mucin MUC4 is potently anti-adhesive to cultured tumor cells, and suppresses cellular apoptotic response to a variety of insults. Such observations raise the possibility that MUC4 expression could contribute to tumor progression or metastasis, but the potential involvement of MUC4 in breast cancer has not been rigorously assessed. The present study aimed to investigate the expression of the membrane mucin MUC4 in normal breast tissue, primary breast tumors and lymph node metastases, and to evaluate the role of MUC4 in promoting the malignant properties of breast tumor cells.

Methods

MUC4 expression levels in patient-matched normal and tumor breast tissue was initially examined by immunoblotting lysates of fresh frozen tissue samples with a highly specific preparation of anti-MUC4 monoclonal antibody 1G8. Immunohistochemical analysis was then carried out using tissue microarrays encompassing patient-matched normal breast tissue and primary tumors, and patient-matched lymph node metastases and primary tumors. Finally, shRNA-mediated knockdown was employed to assess the contribution of MUC4 to the cellular growth and malignancy properties of JIMT-1 breast cancer cells.

Results

Immunoblotting and immunohistochemistry revealed that MUC4 levels are suppressed in the majority (58%, p < 0.001) of primary tumors relative to patient-matched normal tissue. On the other hand, lymph node metastatic lesions from 37% (p < 0.05) of patients expressed higher MUC4 protein levels than patient-matched primary tumors. MUC4-positive tumor emboli were often found in lymphovascular spaces of lymph node metastatic lesions. shRNA-mediated MUC4 knockdown compromised the migration, proliferation and anoikis resistance of JIMT-1 cells, strongly suggesting that MUC4 expression actively contributes to cellular properties associated with breast tumor metastasis.

Conclusions

Our observations suggest that after an initial loss of MUC4 levels during the transition of normal breast tissue to primary tumor, the re-establishment of elevated MUC4 levels confers an advantage to metastasizing breast tumor cells by promoting the acquisition of cellular properties associated with malignancy.

Convergent syntheses of Le analogues

The synthesis of three Le^x derivatives from one common protected trisaccharide is reported. These analogues will be used respectively for competitive binding experiments, conjugation to carrier proteins and immobilization on gold. An N-acetylglucosamine monosaccharide acceptor was first glycosylated at O-4 with a galactosyl imidate. This coupling was performed at 40 °C under excess of BF₃·OEt₂ activation and proceeded best if the acceptor carried a 6-chlorohexyl rather than a 6-azidohexyl aglycon. The 6-chlorohexyl disaccharide was then converted to an acceptor and submitted to fucosylation yielding the corresponding protected 6-chlorohexyl Le^x trisaccharide. This protected trisaccharide was used as a precursor to the 6-azidohexyl, 6-acetylthiohexyl and 6-benzylthiohexyl trisaccharide analogues which were obtained in excellent yields (70–95%). In turn, we describe the deprotection of these intermediates in one single step using dissolving metal conditions. Under these conditions, the 6-chlorohexyl and 6-azidohexyl intermediates led respectively to the n-hexyl and 6-aminohexyl trisaccharide targets. Unexpectedly, the 6-acetylthiohexyl analogue underwent desulfurization and gave the n-hexyl glycoside product, whereas the 6-benzylthiohexyl analogue gave the desired disulfide trisaccharide dimer. This study constitutes a particularly efficient and convergent preparation of these three Le^x analogues.

Consequences of the expression of sialylated antigens in breast cancer

Changes in cell surface glycosylation are common modifications that occur during oncogenesis, leading to the over-expression of tumour-associated carbohydrate antigens (TACA). Most of these antigens are sialylated and the increase of sialylation is a well-known feature of transformed cells. In breast cancer, expression of TACA such as sialyl-Lewis(x) or sialyl-Tn is usually associated with a poor prognosis and a decreased overall survival of patients. However, the specific role of these sialylated antigens in breast tumour development and aggressiveness is not clearly understood. These glycosylation changes result from the modification of the expression of genes encoding specific glycosyltransferases involved in glycan biosynthesis and the level of expression of sialyltransferase genes has been proposed to be a prognostic marker for the follow-up of breast cancer patients. Several human cellular models have been developed in order to explain the mechanisms by which carbohydrate antigens can reinforce breast cancer progression and aggressiveness. TACA expression is associated with changes in cell adhesion, migration, proliferation and tumour growth. In addition, recent data on glycolipid biosynthesis indicate an important role of G(D3) synthase expression in breast cancer progression. The aim of this review is to summarize our current knowledge of sialylation changes that occur in breast cancer and to describe the cellular models developed to analyze the consequences of these changes on disease progression and aggressiveness.

Differentiation of isomeric Lewis blood groups by positive ion electrospray tandem mass spectrometry

Lewis histo-blood group antigens are one of the major classes of biologically active oligosaccharides. In this work, underivatized Lewis blood groups were studied by electrospray tandem mass spectrometry (ESI-MS(n)) in the positive mode with three different mass analyzers: Q-TOF (quadrupole time-of-flight), QqQ (triple quadrupole), and LIT (linear ion trap). It was observed that, under collision-induced fragmentations, type 1 Lewis antigens (Le(a) and Le(b)) could be distinguished from type 2 (Le(x) and Le(y)) on the basis of specific fragmentations of the GlcNAc unit. Whereas O-4-linked sugars of the GlcNAc are lost as residues, the O-3-linked sugars undergo fragmentation both as sugar units and as sugar residues (unit -18Da). Type 2 Lewis antigens also showed a characteristic cross-ring cleavage (0,2)A(2) of the GlcNAc. As a result, the product ions at m/z 388 and 305, characteristic of Le(x), and m/z 372, characteristic of Le(a), are proposed to distinguish the trisaccharide isomers Le(x)/Le(a). Also, the product ions at m/z 534 and 305, characteristic of Le(y), and m/z 372, characteristic of Le(b), are proposed to distinguish the tetrasaccharide isomers Le(b)/Le(y). These diagnostic fragment ions were further applied in the identification of Lewis type 2 antigens (Le(x) and Le(y)) in the lipopolysaccharide of the human gastric pathogen, Helicobacter pylori.

Glycan gimmickry by parasitic helminths: a strategy for modulating the host immune response?

Parasitic helminths (worms) co-evolved with vertebrate immune systems to enable long-term survival of worms in infected hosts. Among their survival strategies, worms use their glycans within glycoproteins and glycolipids, which are abundant on helminth surfaces and in their excretory/ secretory products, to regulate and suppress host immune responses. Many helminths express unusual and antigenic (nonhost-like) glycans, including those containing polyfucose, tyvelose, terminal GalNAc, phosphorylcholine, methyl groups, and sugars in unusual linkages. In addition, some glycan antigens are expressed that share structural features with those in their intermediate and vertebrate hosts (host-like glycans), including Le(X) (Galbeta1-4[Fucalpha1-3]GlcNAc-), LDNF (GalNAcbeta1-4[Fucalpha1-3]GlcNAc-), LDN (GalNAcbeta1-4GlcNAc-), and Tn (GalNAcalpha1-O-Thr/Ser) antigens. The expression of host-like glycan determinants is remarkable and suggests that helminths may gain advantages by synthesizing such glycans. The expression of host-like glycans by parasites previously led to the concept of "molecular mimicry," in which molecules are either derived from the pathogen or acquired from the host to evade recognition by the host immune system. However, recent discoveries into the potential of host glycan-binding proteins (GBPs), such as C-type lectin receptors and galectins, to functionally interact with various host-like helminth glycans provide new insights. Host GBPs through their interactions with worm-derived glycans participate in shaping innate and adaptive immune responses upon infection. We thus propose an alternative concept termed "glycan gimmickry," which is defined as an active strategy of parasites to use their glycans to target GBPs within the host to promote their survival.

Breast cancer humoral immune response: involvement of Lewis y through the detection of circulating immune complexes and association with Mucin 1 (MUC1)

Background

In cancer patients, MUC1 glycoprotein may carry Lewis y which could be involved in immune response. Purposes: 1- to evaluate the presence of Lewis y and MUC1 in circulating immune complexes (Lewis y/CIC and MUC1/CIC, respectively) and their correlation; 2- to analyze the possible presence of Lewis y in carbohydrate chains of tumoral MUC1 glycoprotein and 3- to correlate serum and tissue parameters considered.

Methods

Pretreatment serum and tissue breast samples from 76 adenocarcinoma, 34 benign and 36 normal specimens were analyzed. Anti-MUC1 and anti-Lewis y MAbs were employed. To detect Lewis y/CIC and MUC1/CIC, ELISA tests were developed; serum samples containing MUC1 were previously selected by Cancer Associated Serum Antigen (CASA). Immunoprecipitation (IP) was performed in 9 malignant, benign and normal samples and analyzed by SDS-PAGE and Western blot. Lewis y and MUC1 expression was studied by immunohistochemistry (IHC). Statistical analysis was performed employing principal component analysis (PCA), ANOVA, Tukey HSD, Chi square test and classical correlation (p < 0.05).

Results

By ELISA, Lewis y/IgM/CIC levels showed statistically significant differences between breast cancer versus benign and normal samples; mean ± SD values expressed in OD units were: 0.525 ± 0.304; 0.968 ± 0.482 and 0.928 ± 0.447, for breast cancer, benign disease and normal samples, respectively, p < 0.05. Lewis y/IgG/CIC did not show any statistically significant difference. MUC1/IgM/CIC correlated with Lewis y/IgM/CIC. By CASA, 9 samples with MUC1 values above the cut off were selected and IP was performed, followed by SDS-PAGE and Western blot; bands at 200 kDa were obtained with each MAb in all the samples. By IHC, with C14 MAb, 47.5%, 31% and 35% of malignant, benign and normal samples, respectively, showed positive reaction while all the samples were positive with anti-MUC1 MAb; in both cases, with a different pattern of expression between malignant and non malignant samples.

Conclusion

Our findings support that in breast cancer there was a limited humoral immune response through Lewis y/IgM/CIC levels detection which correlated with MUC1/IgM/CIC. We also found that Lewis y might be part of circulating MUC1 glycoform structure and also that Lewis y/CIC did not correlate with Lewis y expression.