Carbohydrate-mediated cell adhesion involved in hematogenous metastasis of cancer

Assessment of Serum Fucose Level among Oral Squamous Cell Carcinoma Patients: A Case-Control Study

Background

Serum glycoproteins, which are made up of various monosaccharides, are altered in malignancy, a disorder of cellular conduct. L-fucose, a methyl pentose that serves as the last sugar in the majority of plasma glycoproteins, is one of the monosaccharides. Numerous illness conditions and cancers have been linked to increased levels of protein-bound fucose.

Materials and Methods

In the current study, the serum fucose levels of patients with oral squamous cell carcinoma (OSCC) and healthy individuals were assessed and compared. The present study included a total of 30 OSCC patients and 30 healthy controls. The Winzler method was used to estimate the serum L-fucose levels using a spectrophotometer (Spectronic 20, Thermo Fisher Scientific, USA).

Results

Age and sex had no effect on serum fucose levels. In contrast to healthy individuals, OSCC patients' mean serum fucose levels significantly increased. In conclusion, patients with OSCC can benefit from the use of serum fucose as an investigative biomarker.

Effective Organotin-Mediated Regioselective Functionalization of Unprotected Carbohydrates

Regioselective functionalization of unprotected carbohydrates at a secondary OH group in the presence of primary OH groups based on the commonly used organotin-mediated reaction has been improved. We found that the preactivation of the dibutylstannylene acetal intermediate with tetrabutylammonium bromide in toluene is a key to the improved condition for the efficient, high-yielding, and regioselective tosylation, benzoylation, or benzylation of unprotected carbohydrates. The counteranion of tetrabutylammonium ion with a weak coordination ability plays a crucial role in the improved regioselective reactions. A convenient access to the intermediates of synthetic value is also demonstrated in the organotin-mediated regioselective tosylation of unprotected carbohydrates, followed by the nucleophilic inversion reaction to give sulfur-containing and azide-modified carbohydrates.

The biology of E-selectin ligands in leukemogenesis

Both the cascade whereby a blood-borne cell enters a tissue and the anchoring of hematopoietic stem/progenitor cells (HSPCs) within bone marrow critically pivots on cell-cell interactions mediated by E-selectin binding to its canonical carbohydrate ligand, the tetrasaccharide termed "sialylated Lewis X" (sLeX). E-selectin, a member of the selectin class of adhesion molecules that is exclusively expressed by vascular endothelium, engages sLeX-bearing glycoconjugates that adorn mature leukocytes and HSPCs, as well as malignant cells, thereby permitting these cells to extravasate into various tissues. E-selectin expression is induced on microvascular endothelial cells within inflammatory loci at all tissues. However, conspicuously, E-selectin is constitutively expressed within microvessels in skin and marrow and, additionally, is inducibly expressed at these sites. Within the marrow, E-selectin receptor/ligand interactions promote lodgment of HSPCs and their malignant counterparts within hematopoietic growth-promoting microenvironments, collectively known as "vascular niches". Indeed, E-selectin receptor/ligand interactions have been reported to regulate both hematopoietic stem, and leukemic, cell proliferative dynamics. As such, signaling induced via engagement of E-selectin ligands is gaining interest as a critical mediator of homeostatic and malignant hematopoiesis, and this review will present current perspectives on the glycoconjugates mediating E-selectin receptor/ligand interactions and their currently defined role(s) in leukemogenesis.

Proposal of sialyl Lewis x/a as prognostic biomarkers in clear cell renal cell carcinoma: A study on a cohort of 117 patients submitted to curative surgery

Objective:

Metastatic recurrence has been reported to occur in 20–30% of patients with clear cell renal cell carcinoma (ccRCC). Although the prognosis of these patients is poor, no marker has been established to predict metastatic potential and/or prognosis. Therefore, we investigated membrane expression of sialyl Lewis x (sLex) and sialyl Lewis a (sLea), which is generally considered to be associated with cancer metastasis.

Materials and methods:

We enrolled 117 patients who underwent curative surgery for RCC and were pathologically diagnosed as ccRCC. Immunohistochemistry for sLex and sLea was performed to evaluate the signal intensity on the cell membrane. We statistically analysed whether membrane expression of sLex/sLea is correlated with clinicopathological parameters and prognosis.

Results:

Of the 117 patients, 72 were classified as sLex-positive and 44 as sLea-positive. The sLex-positive group had significantly shorter progression-free survival (PFS) and overall survival (OS) than the negative group. Similarly, the sLea-positive group had significantly shorter PFS than the negative group, and it showed a trend towards a reduction of OS, although it did not reach statistical significance, a fact that could be due to the small sample size.

Conclusion:

Both sLex and sLea could be possible future prognostic indicators in ccRCC.

Level of evidence:

Level 3

Immunological insights of selectins in human disease mechanism

Selectin enzymes are glycoproteins and are an important adhesion molecule in the mammalian immune system, especially in the inflammatory response and the healing process of tissues. Selectins play an important role in a variety of biological processes, including the rolling of leukocytes in endothelial cells, a process known as the adhesion cascade. It has recently been discovered and reported that the selectin mechanism plays a role in cancer and thrombosis disease. This process begins with non-covalent interactions-based selectin-ligand binding and the glycans play a role as a connector between cancer cells and the endothelium in this process. The selectin mechanism is critical for the immune system, but it is also involved in disease mechanisms, earning the selectins the nickname "Selectins-The Two Dr. Jekyll and Mr. Hyde Faces". As a result, the drug for selectins should have a multifaceted role and be a dynamic molecule that targets the disease mechanism specifically. This chapter explores the role of selectins in the disease mechanism at the mechanism level that provides the impact for identifying the selectin inhibitors. Overall, this chapter provides the molecular level insights on selectins, their ligands, involvement in normal and disease mechanisms.

AMIGO2 contained in cancer cell-derived extracellular vesicles enhances the adhesion of liver endothelial cells to cancer cells

Adhesion of cancer cells to vascular endothelial cells in target organs is an initial step in cancer metastasis. Our previous studies revealed that amphoterin-induced gene and open reading frame 2 (AMIGO2) promotes the adhesion of tumor cells to liver endothelial cells, followed by the formation of liver metastasis in a mouse model. However, the precise mechanism underlying AMIGO2-promoted the adhesion of tumor cells and liver endothelial cells remains unknown. This study was conducted to explore the role of cancer cell-derived AMIGO2-containing extracellular vesicles (EVs) in the adhesion of cancer cells to human hepatic sinusoidal endothelial cells (HHSECs). Western blotting indicated that AMIGO2 was present in EVs from AMIGO2-overexpressing MKN-28 gastric cancer cells. The efficiency of EV incorporation into HHSECs was independent of the AMIGO2 content in EVs. When EV-derived AMIGO2 was internalized in HHSECs, it significantly enhanced the adhesion of HHSECs to gastric (MKN-28 and MKN-74) and colorectal cancer cells (SW480), all of which lacked AMIGO2 expression. Thus, we identified a novel mechanism by which EV-derived AMIGO2 released from AMIGO2-expressing cancer cells stimulates endothelial cell adhesion to different cancer cells for the initiate step of liver metastasis.

A panel of differentially methylated regions enable prognosis prediction for colorectal cancer

We aim to identify a panel of differentially methylated regions (DMRs) for predicting survival outcomes for patients with CRC from the TCGA (n = 393). Four DMRs (MUC12, TBX20, CHN2, and B3GNT7) were selected as candidate prognostic markers for CRC. The prediction potential of selected DMRs was validated by the targeted bisulfite sequencing method in an independent cohort with 251 Chinese CRC patients. DMR methylation scores (DMSs) were constructed to evaluate the prognosis of CRC. Results of the validation cohort confirmed that higher DMSs were associated with poor overall survival (OS) of CRC, with hazard ratio (HR) value ranged from 1.445 to 2.698 in multivariable Cox models. Patients in the high prognostic index (high-PI) group showed a markedly unfavorable prognosis compared to the low-PI group in both TCGA discovery cohort (HR = 3.508, 95%CI: 2.196-5.604, P < 0.001) and independent validation cohort (HR = 1.912, 95%CI: 1.258-2.907, P = 0.002).

Mucin-Type O-GalNAc Glycosylation in Health and Disease

Mucin-type GalNAc O-glycosylation is one of the most abundant and unique post-translational modifications. The combination of proteome-wide mapping of GalNAc O-glycosylation sites and genetic studies with knockout animals and genome-wide analyses in humans have been instrumental in our understanding of GalNAc O-glycosylation. Combined, such studies have revealed well-defined functions of O-glycans at single sites in proteins, including the regulation of pro-protein processing and proteolytic cleavage, as well as modulation of receptor functions and ligand binding. In addition to isolated O-glycans, multiple clustered O-glycans have an important function in mammalian biology by providing structural support and stability of mucins essential for protecting our inner epithelial surfaces, especially in the airways and gastrointestinal tract. Here the many O-glycans also provide binding sites for both endogenous and pathogen-derived carbohydrate-binding proteins regulating critical developmental programs and helping maintain epithelial homeostasis with commensal organisms. Finally, O-glycan changes have been identified in several diseases, most notably in cancer and inflammation, where the disease-specific changes can be used for glycan-targeted therapies. This chapter will review the biosynthesis, the biology, and the translational perspectives of GalNAc O-glycans.

How Dysregulated Ion Channels and Transporters Take a Hand in Esophageal, Liver, and Colorectal Cancer

Over the last two decades, the understanding of how dysregulated ion channels and transporters are involved in carcinogenesis and tumor growth and progression, including invasiveness and metastasis, has been increasing exponentially. The present review specifies virtually all ion channels and transporters whose faulty expression or regulation contributes to esophageal, hepatocellular, and colorectal cancer. The variety reaches from Ca²⁺, K⁺, Na⁺, and Cl^- channels over divalent metal transporters, Na⁺ or Cl^- coupled Ca²⁺, HCO₃^- and H⁺ exchangers to monocarboxylate carriers and organic anion and cation transporters. In several cases, the underlying mechanisms by which these ion channels/transporters are interwoven with malignancies have been fully or at least partially unveiled. Ca²⁺, Akt/NF-κB, and Ca²⁺- or pH-dependent Wnt/β-catenin signaling emerge as cross points through which ion channels/transporters interfere with gene expression, modulate cell proliferation, trigger epithelial-to-mesenchymal transition, and promote cell motility and metastasis. Also miRs, lncRNAs, and DNA methylation represent potential links between the misexpression of genes encoding for ion channels/transporters, their malfunctioning, and cancer. The knowledge of all these molecular interactions has provided the basis for therapeutic strategies and approaches, some of which will be broached in this review.

Nucleolin-Sle A Glycoforms as E-Selectin Ligands and Potentially Targetable Biomarkers at the Cell Surface of Gastric Cancer Cells

BACKGROUND

Gastric cancer (GC) is a major health burden worldwide, with half of patients developing metastases within 5 years after treatment, urging novel biomarkers for diagnosis and efficient therapeutic targeting. Sialyl-Lewis A (SLeA), a terminal glycoepitope of glycoproteins and glycolipids, offers tremendous potential towards this objective. It is rarely expressed in healthy tissues and blood cells, while it is present in highly metastatic cell lines and metastases. SLeA is also involved in E-selectin mediated metastasis, making it an ideal target to control disease dissemination.

METHODS AND RESULTS

To improve cancer specificity, we have explored the SLeA-glycoproteome of six GC cell models, with emphasis on glycoproteins showing affinity for E-selectin. A novel bioinformatics-assisted algorithm identified nucleolin (NCL), a nuclear protein, as a potential targetable biomarker potentially involved in metastasis. Several immunoassays, including Western blot and in situ proximity ligation reinforced the existence of cell surface NCL-SLeA glycoforms in GC. The NCL-SLeA glycophenotype was associated with decreased survival and was not reflected in relevant healthy tissues.

CONCLUSIONS

NCL-SLeA is a biomarker of poor prognosis in GC holding potential for precise cancer targeting. This is the first report describing SLeA in preferentially nuclear protein, setting a new paradigm for cancer biomarkers discovery and targeted therapies.

Novel staging system using carbohydrate antigen (CA) 19-9 in extra-hepatic cholangiocarcinoma and its implications on overall survival

BACKGROUND

CA19-9 elevation has shown to be associated with poor prognosis in extrahepatic cholangiocarcinoma (ECCA). However, the role of CA19-9 in staging of ECCA has not been evaluated. We hypothesized that CA19-9 elevation is a marker of aggressive biology in ECCA and that inclusion of CA19-9 in the staging system may improve overall survival (OS) discrimination.

METHODS

Patients with ECCA whose CA19-9 levels, irrespective of surgical status, were reported to the National Cancer Database (2004-2015) were included. The patients were classified based on their CA19-9 levels and a new staging system was proposed. Net reclassification improvement (NRI) model was used to assess the predictive improvement in the proposed survival model as compared to AJCC-TNM staging.

RESULTS

Of the 2100 patients included in the study, 626 (32%) and 1474 (68%) had normal and elevated CA19-9 levels (>38 U/ml), respectively. Median OS was lower among patients with elevated CA19-9 level compared to those with CA19-9 level ≤38 U/ml (8.5 vs 16 months, p < 0.01). On multivariate analysis, CA19-9 elevation independently predicted poor prognosis [HR:1.72 (1.46-2.02); p < 0.01] with similar impact as node-positivity, positive resection margins and non-receipt of chemotherapy. We developed a new staging system by incorporating CA19-9 into the 7th edition AJCC TNM staging system. NRI of 46% (95%CI: 39-57%) indicates that the new staging system is substantially effective at re-classifying events at 12 months as compared to AJCC 7th edition.

CONCLUSION

Elevated CA19-9 was found to be an independent risk factor for mortality in ECCA and its inclusion in the proposed staging system improved OS discrimination.

Selectin-Binding Assay by Flow Cytometry

Cell-cell interactions mediated by selectins and their ligand glycans play pivotal roles in a variety of biological processes represented by leukocyte recruitment to inflammatory sites, lymphocyte homing, and extravasation of cancer cells. The interactions are enhanced at least partly through the upregulation of the selectin-ligand glycan expression, which is observed, for instance, during the activation of leukocytes or epithelial-mesenchymal transition of cancer cells. Selectin-binding assays such as cell adhesion assay or rolling assay have long been used to directly evaluate the activity of these cells in the selectin-mediated processes. In this chapter, we introduce a highly quantitative assay by flow cytometry using recombinant selectin-Ig(Fc) chimera proteins, showing our procedure and tips for E-selectin-binding assay of colon cancer cells undergoing epithelial-mesenchymal transition.

Glycan structures and their recognition roles in the human blood group ABH/Ii, Lea, b, x, y and Sialyl Lea,x active cyst glycoproteins

Human ovarian cyst glycoproteins (HOC, cyst gps) isolated from pseudomucinous type of human ovarian cyst fluids is one of the richest and pioneer sources for studying biosynthesis, structures and functional roles of blood group ABH, Le^a,b,x,y, sLe^a and sLe^x active glycoproteins. After 70⁺ years of exploration, four top highlights are shared. (i) an updated concept of glycotopes and their internal structures in cyst gps was composited; (ii) the unknown codes of new genes in secreted cyst gps were unlocked as Le^x and Le^y; (iii) recognition profiles of cyst glycans and a sialic acid-rich (18%) glycan with lectins and antibodies were shown. (iv) Co-expression of Blood Group A/ A-Le^b/y and B/B-Le^b/y active Glycotopes in the same glycan chains were isolated and illustrated. These are the most advanced achievements since 1980.

Limiting tumor seeding as a therapeutic approach for metastatic disease

Here we propose that therapeutic targeting of circulating tumor cells (CTCs), which are widely understood to be the seeds of metastasis, would represent an effective strategy towards limiting numerical expansion of secondary lesions and containing overall tumor burden in cancer patients. However, the molecular mediators of tumor seeding have not been well characterized. This is in part due to the limited number of pre-clinical in vivo approaches that appropriately interrogate the mechanisms by which cancer cells home to arresting organs. It is critical that we continue to investigate the mediators of tumor seeding as it is evident that the ability of CTCs to colonize in distant sites is what drives disease progression even after the primary tumor has been ablated by local modalities. In addition to slowing disease progression, containing metastatic spread by impeding tumor cell seeding may also provide a clinical benefit by increasing the duration of the residence of CTCs in systemic circulation thereby increasing their exposure to pharmacological agents commonly used in the treatment of patients such as chemotherapy and immunotherapies. In this review we will examine the current state of knowledge about the mechanisms of tumor cells seeding as well as explore how targeting this stage of metastatic spreading may provide therapeutic benefit to patients with advanced disease.

Heteromultivalent Glycooligomers as Mimetics of Blood Group Antigens

Precision glycomacromolecules have proven to be important tools for the investigation of multivalent carbohydrate-lectin interactions by presenting multiple glycan epitopes on a highly-defined synthetic scaffold. Herein, we present a new strategy for the versatile assembly of heteromultivalent glycomacromolecules that contain different carbohydrate motifs in proximity within the side chains. A new building block suitable for the solid-phase polymer synthesis of precision glycomacromolecules was developed with a branching point in the side chain that bears a free alkyne and a TIPS-protected alkyne moiety, which enables the subsequent attachment of different carbohydrate motifs by on-resin copper-mediated azide-alkyne cycloaddition reactions. Applying this synthetic strategy, heteromultivalent glycooligomers presenting fragments of histo-blood group antigens and human milk oligosaccharides were synthesized and tested for their binding behavior towards bacterial lectin LecB.

Predictive Value of Serum Carbohydrate Antigen 19-9 (CA19-9) for Early Mortality in Advanced Pancreatic Cancer

INTRODUCTION

Levels of carbohydrate antigen 19-9 (CA19-9) in metastatic pancreatic cancer are used in daily practice as a marker of response to chemotherapy. The association between CA19-9 levels and mortality remains uncertain. This study sought to determine the most accurate level of CA19-9 associated with early mortality, both at diagnosis and during the course of metastatic disease.

METHODS

This research is a retrospective analysis of 64 patients with metastatic adenocarcinoma of the pancreas evaluated from January 2010 to December 2015. A receiver-operating characteristic (ROC) curve analysis was performed to evaluate the CA19-9 value and the association with early death (death within 2 months after diagnosis of advanced disease). The survival analysis was estimated by the Kaplan-Meier method, and variables of interest were assessed by proportional hazards regression Cox models.

RESULTS

The mortality rate was 92.2%, and the estimated median survival was 11.0 months. For the ROC curve analysis of initial CA19-9, an area under the curve of 0.868 (95% confidence interval 0.782 to 0.954) was obtained; the cutoff of 2504 U/ml had a sensitivity of 100% and specificity of 82.8% for early death. The effect of initial CA19-9 and chemotherapy contributed independently to the survival time, and every increase of 1000 CA19-9 units increased the risk of death by 9% (p = 0.0003).

CONCLUSION

CA19-9 levels in advanced pancreatic adenocarcinoma are associated independently with worse prognosis and early death. CA19-9 levels could be considered as a stratification factor for future clinical trials.

α-1,3-Fucosyltransferase-VII siRNA inhibits the expression of SLex and hepatocarcinoma cell proliferation

The increased expression of sialyl-Lewisx (SLe^x) epitope on the surface of tumor cells has been known for decades. However, genetic manipulation of the expression of SLe^x and the role of SLe^x in cancer cell proliferation remains to be fully elucidated. The present study suggested that the monoclonal antibody of SLe^x (KM93) significantly inhibited the proliferation of human hepatocarcinoma (HCC) cells. The expression levels of three sialyl-Lewis oligosaccharide antigens, SLe^x, SLe^a and dimeric SLe^x (SDLe^x), were determined on the cell surface of the MHCC97 human HCC cell line. The expression of SLe^x was markedly higher in MHCC97 cells than in normal liver cells. The expression of SDLe^x was also relatively high, however, no significant difference was observed between normal liver cells and HCC cells. The expression of SLe^a was only detected in trace quantities. Fucosyltransferase (FUT) is the key enzyme of the fucosylation step in the biosynthesis of sialyl-Lewis oligosaccharide antigens. Therefore, the present study investigated the expression of FUTs. It was found that the mRNA and protein expression levels of FUT7 were high in the MHCC97 HCC cell line compared with levels in normal liver cells. FUT6 was also expressed at a high level, although the difference was not statistically significant between MHCC97 cells and normal liver cells. No expression of FUT3 was detected. The results were consistent with the change insialyl-Lewis antigens. The effects of FUT7 small interfering (si)RNA transfection on the expression of FUT7, expression of SLe^x and MHCC97 cell proliferation were also examined. Following FUT7 siRNA transfection, the expression of FUT7 was markedly downregulated, as determined by western blot and reverse transcription-quantitative polymerase chain reaction methods. The results from flow cytometry showed that the synthesis of SLe^x was also inhibited, which was consistent with the downregulated expression of FUT7. MHCC97 cell proliferation was also significantly inhibited following FUT7 siRNA transfection, which was correlated with suppression of the S-phase in cell cycle progression. By using inhibitors of various signaling pathways, it was found that the knockdown of FUT7 inhibited the activation of phospholipase Cγ (PLCγ) by inhibiting the translocation and phosphorylation of PLCγ. In conclusion, the results suggested that FUT7 has animportant functional role in human HCC cell proliferation by controlling cell cycle progression via the PLCγ/extracellular signal-regulated kinase signaling pathway. The inhibition of SLe^x and FUT7 siRNA transfection may provide a novel therapeutic methodology to treat tumors that express SLe^x glycoconjugates.

Analysis of adhesion kinetics of cancer cells on inflamed endothelium using a microfluidic platform

Metastasis is the ultimate cause of death among the vast majority of cancer patients. This process is comprised of multiple steps, including the migration of circulating cancer cells across microvasculature. This trans-endothelial migration involves the adhesion and eventual penetration of cancer cells to the vasculature of the target organ. Many of these mechanisms remain poorly understood due to poor control of pathophysiological conditions in tumor models. In this work, a microfluidic device was developed to support the culture and observation of engineered microvasculature with systematic control of the environmental characteristics. This device was then used to study the adhesion of circulating cancer cells to an endothelium under varying conditions to delineate the effects of hemodynamics and inflammations. The resulting understanding will help to establish a quantitative and biophysical mechanism of interactions between cancer cells and endothelium.

Biological functions of fucose in mammals

Fucose is a 6-deoxy hexose in the l-configuration found in a large variety of different organisms. In mammals, fucose is incorporated into N-glycans, O-glycans and glycolipids by 13 fucosyltransferases, all of which utilize the nucleotide-charged form, GDP-fucose, to modify targets. Three of the fucosyltransferases, FUT8, FUT12/POFUT1 and FUT13/POFUT2, are essential for proper development in mice. Fucose modifications have also been implicated in many other biological functions including immunity and cancer. Congenital mutations of a Golgi apparatus localized GDP-fucose transporter causes leukocyte adhesion deficiency type II, which results in severe developmental and immune deficiencies, highlighting the important role fucose plays in these processes. Additionally, changes in levels of fucosylated proteins have proven as useful tools for determining cancer diagnosis and prognosis. Chemically modified fucose analogs can be used to alter many of these fucose dependent processes or as tools to better understand them. In this review, we summarize the known roles of fucose in mammalian physiology and pathophysiology. Additionally, we discuss recent therapeutic advances for cancer and other diseases that are a direct result of our improved understanding of the role that fucose plays in these systems.

α2,3-sialyltransferase type I regulates migration and peritoneal dissemination of ovarian cancer cells

Epithelial ovarian cancer (EOC) has the highest mortality rate among gynecologic cancers due to advanced stage presentation, peritoneal dissemination, and refractory ascites at diagnosis. We investigated the role of α2,3-sialyltransferase type I (ST3GalI) by analyzing human ovarian cancer datasets and human EOC tissue arrays. We found that high expression of ST3GalI was associated with advanced stage EOC. Transwell migration and cell invasion assays showed that high ST3GalI expression enhanced migration of EOC cells. We also observed that there was a linear relation between ST3GalI expression and epidermal growth factor receptor (EGFR) signaling in EOC patients, and that high ST3GalI expression blocked the effect of EGFR inhibitors. Co-Immunoprecipitation experiments demonstrated that ST3GalI and EGFR were present in the same protein complex. Inhibition of ST3GalI using a competitive inhibitor, Soyasaponin I (SsaI), inhibited tumor cell migration and dissemination in the in vivo mouse model with transplanted MOSEC cells. Further, SsaI synergistically enhanced the anti-tumor effects of EGFR inhibitor on EOC cells. Our study demonstrates that ST3GalI regulates ovarian cancer cell migration and peritoneal dissemination via EGFR signaling. This suggests α2,3-linked sialylation inhibitors in combination with EGFR inhibitors could be effective agents for the treatment of EOC.

Glycosylation Changes in Brain Cancer

Protein glycosylation is a posttranslational modification that affects more than half of all known proteins. Glycans covalently bound to biomolecules modulate their functions by both direct interactions, such as the recognition of glycan structures by binding partners, and indirect mechanisms that contribute to the control of protein conformation, stability, and turnover. The focus of this Review is the discussion of aberrant glycosylation related to brain cancer. Altered sialylation and fucosylation of N- and O-glycans play a role in the development and progression of brain cancer. Additionally, aberrant O-glycan expression has been implicated in brain cancer. This Review also addresses the clinical potential and applications of aberrant glycosylation for the detection and treatment of brain cancer. The viable roles glycans may play in the development of brain cancer therapeutics are addressed as well as cancer-glycoproteomics and personalized medicine. Glycoprotein alterations are considered as a hallmark of cancer while high expression in body fluids represents an opportunity for cancer assessment.

Use of Mass Spectrometry to Screen Glycan Early Markers in Hepatocellular Carcinoma

Association between altered glycosylation patterns and poor prognosis in cancer points glycans as potential specific tumor markers. Most proteins are glycosylated and functionally arranged on cell surface and extracellular matrix, mediating interactions and cellular signaling. Thereby, aberrant glycans may be considered a pathological phenotype at least as important as changes in protein expression for cancer and other complex diseases. As most serum glycoproteins have hepatic origin, liver disease phenotypes, such as hepatocellular carcinoma (HCC), may present altered glycan profile and display important modifications. One of the prominent obstacles in HCC is the diagnostic in advanced stages when patients have several liver dysfunctions, limiting treatment options and life expectancy. The characterization of glycomic profiles in pathological conditions by means of mass spectrometry (MS) may lead to the discovery of early diagnostic markers using non-invasive approaches. MS is a powerful analytical technique capable of elucidating many glycobiological issues and overcome limitations of the serological markers currently applied in clinical practice. Therefore, MS-based glycomics of tumor biomarkers is a promising tool to increase early detection and monitoring of disease.

Gangliosides and Tumors

Tumor-associated gangliosides play important roles in regulation of signal transduction induced by growth-factor receptors including EGFR, FGFR, HGF and PDGFR in a specific microdomain called glycosynapse in the cancer cell membranes, and in interaction with glycan recognition molecules involved in cell adhesion and immune regulation including selectins and siglecs. As the genes involved in the synthesis and degradation of tumor-associated gangliosides were identified, biological functions became clearer from the experimental results employing forced overexpression and/or knockdown/knockout of the genes. Studies on the regulatory mechanisms for their expression also achieved great advancements. Epigenetic silencing of glycan-related genes is a dominant mechanism in glycan alteration at early stages of carcinogenesis. Development of hypoxia resistance involving activation of a transcription factor HIF, and acquisition of cancer stem cell-like characteristics through epithelial-mesenchymal transition are important mechanisms for glycan modulations in the later stages of cancer progression. In the initial stages of studies, the gangliosides which specifically appear in cancers attracted attention under the name of tumor-associated gangliosides. However, it became apparent that not only the cancer-associated gangliosides but also the normal gangliosides present in nonmalignant cells and tissues perform important biological functions, and some of them tend to disappear in cancer cells resulting in the loss of the physiological functions, and this sometimes facilitates progression of cancers.

Biological roles of glycans

Simple and complex carbohydrates (glycans) have long been known to play major metabolic, structural and physical roles in biological systems. Targeted microbial binding to host glycans has also been studied for decades. But such biological roles can only explain some of the remarkable complexity and organismal diversity of glycans in nature. Reviewing the subject about two decades ago, one could find very few clear-cut instances of glycan-recognition-specific biological roles of glycans that were of intrinsic value to the organism expressing them. In striking contrast there is now a profusion of examples, such that this updated review cannot be comprehensive. Instead, a historical overview is presented, broad principles outlined and a few examples cited, representing diverse types of roles, mediated by various glycan classes, in different evolutionary lineages. What remains unchanged is the fact that while all theories regarding biological roles of glycans are supported by compelling evidence, exceptions to each can be found. In retrospect, this is not surprising. Complex and diverse glycans appear to be ubiquitous to all cells in nature, and essential to all life forms. Thus, >3 billion years of evolution consistently generated organisms that use these molecules for many key biological roles, even while sometimes coopting them for minor functions. In this respect, glycans are no different from other major macromolecular building blocks of life (nucleic acids, proteins and lipids), simply more rapidly evolving and complex. It is time for the diverse functional roles of glycans to be fully incorporated into the mainstream of biological sciences.

Extract of Caulis Spatholobi, a novel blocker targeting tumor cell‑induced platelet aggregation, inhibits breast cancer metastasis

Metastasis of breast cancer is the vital step for malignant progression. During such a process, hematogenous metastasis is an indispensable approach for the dissemination of cancer cells. A platelet, contributes to hypercoagulable state, and is also identified the crucial factor in the coagulation system for supporting metastasis. Therefore, the relationship of a platelet and a tumor cell plays a critical role in tumor cell metastasis. Consequently, inhibiting tumor cell‑induced platelet aggregation (TCIPA) is recongnized as a crucial target on suppression of tumor metastasis such as aspirin (ASA). Under such circumstance, here we report that, through dissociating the tumor‑platelet (T‑P) complex, 80% ethanol extracts of Caulis Spatholobi (SET) successfully alleviated the hypercoagulation state, thereby reducing tumor metastasis and improving the prospects of survival in breast cancer cell model. Through MTT and anti‑aggregation assay stimulated by ADP, we detected the optimum treatment time and the optimum dose of SET. By using confocal microscopy, we observed that SET can strongly block the formation of T‑P complex in vitro. The result was further quantified and confirmed by the FACS analysis. The fluorescent value of T‑P complex was obviously decreased in the drug‑treated groups. In vivo, 4T1 cells were injected through the mouse tail vein for dynamic visualization by small animal imaging system. The metastatic intensity was quantified and the survival curve was analyzed. Additionally, general observation and hematoxylin and eosin (H&E) staining of lung tissue was performed. SET exerted an obvious effect on the inhibition of metastasis and increasing the survival rate of mice. For the molecular mechanism study of anti‑TCIPA, zymography and RT‑PCR assay preliminarily revealed the molecular mechanism of SET in the regulation of P‑T interaction. Collectively, through drug efficacy identification and pharmacological revealing, we have obtained a promising candidate for the interference of breast metastasis by suppressing TCIPA, which will be beneficial for clinical cancer treatment.

Implications of CA19-9 elevation for survival, staging, and treatment sequencing in intrahepatic cholangiocarcinoma: A national cohort analysis

BACKGROUND

Optimal management of patients with intrahepatic cholangiocarcinoma (ICCA) and elevated CA19-9 remains undefined. We hypothesized CA19-9 elevation above normal indicates aggressive biology and that inclusion of CA19-9 would improve staging discrimination.

METHODS

The National Cancer Data Base (NCDB-2010-2012) was reviewed for patients with ICCA and reported CA19-9. Patients were stratified by CA19-9 above/below normal reference range. Unadjusted Kaplan-Meier and adjusted Cox-proportional-hazards analysis of overall survival (OS) were performed.

RESULTS

A total of 2,816 patients were included: 938 (33.3%) normal; 1,878 (66.7%) elevated CA19-9 levels. Demographic/pathologic and chemotherapy/radiation were similar between groups, but patients with elevated CA19-9 had more nodal metastases and less likely to undergo resection. Among elevated-CA19-9 patients, stage-specific survival was decreased in all stages. Resected patients with CA19-9 elevation had similar peri-operative outcomes but decreased long-term survival. In adjusted analysis, CA19-9 elevation independently predicted increased mortality with impact similar to node-positivity, positive-margin resection, and non-receipt of chemotherapy. Proposed staging system including CA19-9 improved survival discrimination over AJCC 7th edition.

CONCLUSION

Elevated CA19-9 is an independent risk factor for mortality in ICCA similar in impact to nodal metastases and positive resection margins. Inclusion of CA19-9 in a proposed staging system increases discrimination. Multi-disciplinary therapy should be considered in patients with ICCA and CA19-9 elevation. J. Surg. Oncol. 2016;114:475-482. © 2016 Wiley Periodicals, Inc.

Application of cancer-associated glycoforms and glycan-binding probes to an in vitro diagnostic multivariate index assay for precise diagnoses of cancer

Personalized medicine has emerged as a widely accepted trend in medicine for the efficacious and safe treatment of various diseases. It covers every medical treatment tailored according to various properties of individuals. Cancer-associated glycosylation mirrors cancer states more precisely, and this "sweet side of cancer" is thus intended to spur the development of an advanced in vitro diagnostic system. The changes of glyco-codes are often subtle and thus not easy to trace, thereby making it difficult to discriminate changes from various compounding factors. Special glycan-binding probes, often lectins, can be paired with aglycosylated antibodies to enable quantitative and qualitative measurements of glycoforms. With the in vitro diagnosis multivariate index assay (IVDMIA) considered to be capable of yielding patient-specific results, the combinatorial use of multiple glycoproteins may be a good modality to ensure disease-specific, personalized diagnoses.

Glycomic analysis of gastric carcinoma cells discloses glycans as modulators of RON receptor tyrosine kinase activation in cancer

BACKGROUND

Terminal α2-3 and α2-6 sialylation of glycans precludes further chain elongation, leading to the biosynthesis of cancer relevant epitopes such as sialyl-Lewis X (SLe(X)). SLe(X) overexpression is associated with tumor aggressive phenotype and patients' poor prognosis.

METHODS

MKN45 gastric carcinoma cells transfected with the sialyltransferase ST3GAL4 were established as a model overexpressing sialylated terminal glycans. We have evaluated at the structural level the glycome and the sialoproteome of this gastric cancer cell line applying liquid chromatography and mass spectrometry. We further validated an identified target expression by proximity ligation assay in gastric tumors.

RESULTS

Our results showed that ST3GAL4 overexpression leads to several glycosylation alterations, including reduced O-glycan extension and decreased bisected and increased branched N-glycans. A shift from α2-6 towards α2-3 linked sialylated N-glycans was also observed. Sialoproteomic analysis further identified 47 proteins with significantly increased sialylated N-glycans. These included integrins, insulin receptor, carcinoembryonic antigens and RON receptor tyrosine kinase, which are proteins known to be key players in malignancy. Further analysis of RON confirmed its modification with SLe(X) and the concomitant activation. SLe(X) and RON co-expression was validated in gastric tumors.

CONCLUSION

The overexpression of ST3GAL4 interferes with the overall glycophenotype of cancer cells affecting a multitude of key proteins involved in malignancy. Aberrant glycosylation of the RON receptor was shown as an alternative mechanism of oncogenic activation.

GENERAL SIGNIFICANCE

This study provides novel targets and points to an integrative tumor glycomic/proteomic-profiling for gastric cancer patients' stratification. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.

Structural Characterization of Mucin O-Glycosylation May Provide Important Information to Help Prevent Colorectal Tumor Recurrence

Although colorectal cancer is a preventable and curable disease if early stage tumors are removed, it still represents the second cause of cancer-related death worldwide. Surgical resection is the only curative treatment but once operated the patient is either subjected to adjuvant chemotherapy or not, depending on the invasiveness of the cancer and risks of recurrence. In this context, we investigated, by mass spectrometry (MS), alterations in the repertoire of glycosylation of mucins from colorectal tumors of various stages, grades, and recurrence status. Tumors were also compared with their counterparts in resection margins from the same patients and with healthy controls. The obtained data showed an important decrease in the level of expression of sialylated core 3-based O-glycans in tumors correlated with an increase in sialylated core 1 structures. No correlation was established between stages of the tumor samples and mucin O-glycosylation. However, with the notable exception of sialyl Tn antigens, tumors with recurrence presented a milder alteration of glycosylation profile than tumors without recurrence. These results suggest that mucin O-glycans from tumors with recurrence might mimic a healthier physiological situation, hence deceiving the immune defense system.

Hodgkin lymphoma cell lines bind to platelets. Incubation with platelets induces CD15 and P-selectin dependent adhesion of the cell lines to Human Umbilical Vein Endothelial cells (HUVEC)

Hodgkin's lymphoma is believed to spread in an orderly fashion within the lymphatic compartment. In a minority of cases, after reaching the spleen, the neoplasm disseminates, reminiscent of metastasis. In the spleen, the Hodgkin-Reed-Sternberg tumor cells come across platelets in the blood vessels and mainly in the splenic red pulp. Based on this knowledge, we investigated the possibility of platelets inducing cell adhesion in Hodgkin's lymphoma cell lines. We showed that L428 and KMH-2 cells strongly adhere to thrombin-activated platelets. Cell adhesion to platelets is partially dependent on CD15 antigens (Lewis(X)), mainly sialyl-CD15, and P-selectin. KMH-2, as compared to L428 cells, showed increased binding due to its differential high expression of the sialyl-CD15. As a consequence of incubation with platelets, KMH-2 cells also produced increased amounts of tumor necrosis factors α (TNFα) followed by enhanced binding to human vascular endothelial cells (HUVEC). Incubation of both cell lines with activated platelets also induced activation of AP-1 transcription complex. Our findings are consistent with the concept that platelets play a critical role in the dissemination of HRS cells in HL, predominantly in the spleen, by increasing cell adhesion and thus promoting their proliferative and migratory properties beyond the lymphatic system.

Biosynthetic Machinery Involved in Aberrant Glycosylation: Promising Targets for Developing of Drugs Against Cancer

Cancer cells depend on altered metabolism and nutrient uptake to generate and keep the malignant phenotype. The hexosamine biosynthetic pathway is a branch of glucose metabolism that produces UDP-GlcNAc and its derivatives, UDP-GalNAc and CMP-Neu5Ac and donor substrates used in the production of glycoproteins and glycolipids. Growing evidence demonstrates that alteration of the pool of activated substrates might lead to different glycosylation and cell signaling. It is already well established that aberrant glycosylation can modulate tumor growth and malignant transformation in different cancer types. Therefore, biosynthetic machinery involved in the assembly of aberrant glycans are becoming prominent targets for anti-tumor drugs. This review describes three classes of glycosylation, O-GlcNAcylation, N-linked, and mucin type O-linked glycosylation, involved in tumor progression, their biosynthesis and highlights the available inhibitors as potential anti-tumor drugs.

Glyconanomaterials: Emerging applications in biomedical research

Carbohydrates constitute the most abundant organic matter in nature, serving as structural components and energy sources, and mediating a wide range of cellular activities. The emergence of nanomaterials with distinct optical, magnetic, and electronic properties has witnessed a rapid adoption of these materials for biomedical research and applications. Nanomaterials of various shapes and sizes having large specific surface areas can be used as multivalent scaffolds to present carbohydrate ligands. The resulting glyconanomaterials effectively amplify the glycan-mediated interactions, making it possible to use these materials for sensing, imaging, diagnosis, and therapy. In this review, we summarize the synthetic strategies for the preparation of various glyconanomaterials. Examples are given where these glyconanomaterials have been used in sensing and differentiation of proteins and cells, as well as in imaging glycan-medicated cellular responses.

Hepatitis B virus X protein specially regulates the sialyl lewis a synthesis among glycosylation events for metastasis

Background

The metastasis of hematogenous cancer cells is associated with abnormal glycosylation such as sialyl lewis antigens. Although the hepatitis B virus X protein (HBx) plays important role in liver disease, the precise function of HBx on aberrant glycosylation for metastasis remains unclear.

Methods

The human hepatocellular carcinoma tissues, HBx transgenic mice and HBx-transfected cells were used to check the correlation of expressions between HBx and Sialyl lewis antigen for cancer metastasis. To investigate whether expression levels of glycosyltransferases induced in HBx-transfected cells are specifically associated with sialyl lewis A (SLA) synthesis, which enhances metastasis by interaction of liver cancer cells with endothelial cells, ShRNA and siRNAs targeting specific glycosyltransferases were used.

Results

HBx expression in liver cancer region of HCC is associated with the specific synthesis of SLA. Furthermore, the SLA was specifically induced both in liver tissues from HBx-transgenic mice and in in vitro HBx-transfected cells. HBx increased transcription levels and activities of α2-3 sialyltransferases (ST3Gal III), α1-3/4 fucosyltransferases III and VII (FUT III and VII) genes, which were specific for SLA synthesis, allowing dramatic cell-cell adhesion for metastatic potential. Interestingly, HBx specifically induced expression of N-acetylglucosamine-β1-3 galactosyltransferase V (β1-3GalT 5) gene associated with the initial synthesis of sialyl lewis A, but not β1-4GalT I. The β1-3GalT 5 shRNA suppressed SLA expression by HBx, blocking the adhesion of HBx-transfected cells to the endothelial cells. Moreover, β1-3GalT 5 silencing suppressed lung metastasis of HBx-transfected cells in in vivo lung metastasis system.

Conclusion

HBx targets the specific glycosyltransferases for the SLA synthesis and this process regulates hematogenous cancer cell adhesion to endothelial cells for cancer metastasis.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-222) contains supplementary material, which is available to authorized users.

Selectins mediate small cell lung cancer systemic metastasis

Metastasis formation is the major reason for the extremely poor prognosis in small cell lung cancer (SCLC) patients. The molecular interaction partners regulating metastasis formation in SCLC are largely unidentified, however, from other tumor entities it is known that tumor cells use the adhesion molecules of the leukocyte adhesion cascade to attach to the endothelium at the site of the future metastasis. Using the human OH-1 SCLC line as a model, we found that these cells expressed E- and P-selectin binding sites, which could be in part attributed to the selectin binding carbohydrate motif sialyl Lewis A. In addition, protein backbones known to carry these glycotopes in other cell lines including PSGL-1, CD44 and CEA could be detected in in vitro and in vivo grown OH1 SCLC cells. By intravital microscopy of murine mesenterial vasculature we could capture SCLC cells while rolling along vessel walls demonstrating that SCLC cells mimic leukocyte rolling behavior in terms of selectin and selectin ligand interaction in vivo indicating that this mechanism might indeed be important for SCLC cells to seed distant metastases. Accordingly, formation of spontaneous distant metastases was reduced by 50% when OH-1 cells were xenografted into E-/P-selectin-deficient mice compared with wild type mice (p = 0.0181). However, as metastasis formation was not completely abrogated in selectin deficient mice, we concluded that this adhesion cascade is redundant and that other molecules of this cascade mediate metastasis formation as well. Using several of these adhesion molecules as interaction partners presumably make SCLC cells so highly metastatic.

High expression of sLex associated with poor survival in Argentinian colorectal cancer patients

AIM

Colorectal cancer (CRC) is one of the most prevalent malignancies in Argentina with 11,043 new cases and 6,596 deaths estimated to have occurred in 2008. The present study was developed to clarify the differential expression of MUC1, MUC2, sLex, and sLea in colorectal cancer patients and their relationship with survival and clinical and histological features.

METHODS

Ninety primary tumor samples and 43 metastatic lymph nodes from CRC patients were studied; follow-up was documented. Twenty-six adenoma and 68 histological normal mucosa specimens were analyzed. An immunohistochemical approach was applied and statistical analysis was performed.

RESULTS

In tumor samples, MUC1, sLea, and sLex were highly expressed (94%, 67%, and 91%, respectively); also, we found a significantly increased expression of the 3 antigens in primary tumors and metastatic lymph nodes compared with normal mucosa and adenomas. MUC2 was expressed in 52% of both normal mucosa and CRC samples; this reactivity significantly decreased in metastatic lymph nodes (p<0.05). A multiple comparison analysis showed that MUC1 and sLex discriminated among 3 groups: normal, adenoma, and CRC tissues. The increase of sLex expression showed an association with recurrence, and survival analysis showed that a high sLex staining was significantly associated with a poor survival. By multivariate analysis MUC1 inmunoreactivity correlated positively and significantly with tumor size, while MUC2 expression showed the opposite correlation.

CONCLUSIONS

The correlation of sLex overexpression in primary tumors and metastatic lymph nodes, the discrimination among the normal, adenoma, and CRC groups based on sLex expression, as well as its association with recurrence and survival, all suggest a prognostic role of sLex in Argentinian CRC patients.

Altered tumor-cell glycosylation promotes metastasis

Malignant transformation of cells is associated with aberrant glycosylation presented on the cell-surface. Commonly observed changes in glycan structures during malignancy encompass aberrant expression and glycosylation of mucins; abnormal branching of N-glycans; and increased presence of sialic acid on proteins and glycolipids. Accumulating evidence supports the notion that the presence of certain glycan structures correlates with cancer progression by affecting tumor-cell invasiveness, ability to disseminate through the blood circulation and to metastasize in distant organs. During metastasis tumor-cell-derived glycans enable binding to cells in their microenvironment including endothelium and blood constituents through glycan-binding receptors – lectins. In this review, we will discuss current concepts how tumor-cell-derived glycans contribute to metastasis with the focus on three types of lectins: siglecs, galectins, and selectins. Siglecs are present on virtually all hematopoietic cells and usually negatively regulate immune responses. Galectins are mostly expressed by tumor cells and support tumor-cell survival. Selectins are vascular adhesion receptors that promote tumor-cell dissemination. All lectins facilitate interactions within the tumor microenvironment and thereby promote cancer progression. The identification of mechanisms how tumor glycans contribute to metastasis may help to improve diagnosis, prognosis, and aid to develop clinical strategies to prevent metastasis.

Suppression of B3GNT7 gene expression in colon adenocarcinoma and its potential effect in the metastasis of colon cancer cells

The cell surface sialyl Lewis a (sLe(a)) and sialyl Lewis x (sLe(x)) antigens, which are built on the terminals of glyco-structures called poly-N-acetyllactosamine (LacNAc) chains, have been shown to play a critical role in the metastasis of colon cancer. In the present investigation, expression of the B3GNT7 gene, which encodes a β-1,3-N-acetylglucosaminyltransferase that mainly acts on and extends sulfated poly-LacNAc chains, was found to be markedly suppressed during the oncogenetic processes associated with colon cancer. DNA methylation in the promoter region of the B3GNT7 gene was found to play a significant role in the suppression of the B3GNT7 gene in colon cancer cells. The results obtained from Transwell experiments and the nude mice xenograft model demonstrated that ectopic expression of the B3GNT7 gene in colon cancer cells diminished the migration capability and the liver-metastasis potential, respectively, of colon cancer cells. Flow cytometric analysis showed that expression of cell surface sLe(a) and sLe(x) antigens was decreased in colon cancer cells when the B3GNT7 gene was ectopically expressed. Taken together, the results of the present investigation suggest a link between suppression of B3GNT7 gene expression and elevation of sLe(a)/sLe(x) antigen expressions on the surface of cells and that this consequently promotes the metastasis potential of cancer cells as part of the colon cancer oncogenetic process.

Metastatic growth progression caused by PSGL-1-mediated recruitment of monocytes to metastatic sites

Tumor cell-derived selectin ligands mediate contact to the endothelium, platelets, and leukocytes through binding to selectins that facilitates metastasis. Here, we describe the mechanism of how endogenous (non-tumor derived) selectin ligands contribute to metastasis using α(1,3)fucosyltransferase 7 (Fuc-TVII(-/-))-deficient mice. Experimental metastasis of MC-38GFP and Lewis lung (3LL) carcinoma cells was attenuated in Fuc-TVII(-/-) mice, which express minimal amount of selectin ligands. We show that metastasis is dependent on selectin ligands carried on hematopoietic cells. P-selectin glycoprotein ligand-1 (PSGL-1) was identified as the major ligand facilitating monocyte accumulation at metastatic sites. Reduced recruitment of monocytes to metastasizing tumor cells in Fuc-TVII(-/-) mice correlated with attenuated metastasis. Adoptive transfer of Fuc-T7(+) monocytes rescued metastasis in Fuc-TVII(-/-) mice, indicating that selectin ligand-dependent recruitment of monocytes is required for cancer progression. Cytokine analysis in metastatic lungs revealed high expression of CCL2 in C57BL/6 mice that was significantly lower in Fuc-TVII(-/-) mice. The absence of monocyte recruitment in Fuc-TVII(-/-) mice correlated with increased apoptosis of tumor cells. Thus, the recruitment of monocytes to metastasizing tumor cells is facilitated by endogenous selectin ligands on monocytes that enable efficient tumor cell survival, extravasation, and metastasis.

Prognostic molecular markers in head and neck squamous cell carcinoma in a New Zealand population: matrix metalloproteinase-2 and sialyl Lewis x antigen

OBJECTIVE

The survival rate for head and neck squamous cell carcinoma (HNSCC) is among the lowest of the major cancers and has not substantially improved in the past two decades. Tumours with similar histological features may have widely differing clinical outcomes and thus identification of prognostic and predictive biomarkers may be valuable for determining appropriate clinical management strategies. The objective of this study was to establish the prognostic significance of six molecular markers in HNSCC in a New Zealand population: matrix metalloproteinases 2 and 9 (MMP-2, MMP-9), tissue inhibitor of matrix metalloproteinase-1, sialyl Lewis antigens a and x (sLe(a) , sLe(x) ) and alpha B-crystallin.

METHODS

Retrospective review of 145 sequential HNSCC patients from a tertiary centre with minimum 3 years surveillance. Sections from formalin-fixed paraffin-embedded tumour blocks were immunostained for the molecular markers and scored. Cox regression modelling was used to adjust for potential confounding variables impacting on cancer survival.

RESULTS

Multivariate analysis for individual biomarkers, controlling for age, sex, tumour grade, N-stage, T-stage, tumour site, smoking history and alcohol use, revealed poorer survival with tumour expression of MMP-2 (hazard ratio = 1.98, 95% confidence interval: 1.11-3.52, P = 0.021) and sLe(x) (hazard ratio = 3.22, 95% confidence interval: 1.33-7.80, P = 0.010). A stepwise analysis showed that MMP-2 and sLe(x) were independently prognostic after covariate adjustment.

CONCLUSIONS

MMP-2 and sLe(x) were negative prognostic markers for survival in these HNSCC patients. This offers opportunities for clinical trials to reduce the risk of nodal and distant metastases through blocking tumour cell adhesion to endothelium.

Expression of ST3GAL4 leads to SLe(x) expression and induces c-Met activation and an invasive phenotype in gastric carcinoma cells

Sialyl-Lewis X (SLe(x)) is a sialylated glycan antigen expressed on the cell surface during malignant cell transformation and is associated with cancer progression and poor prognosis. The increased expression of sialylated glycans is associated with alterations in the expression of sialyltransferases (STs). In this study we determined the capacity of ST3GAL3 and ST3GAL4 sialyltransferases to synthesize the SLe(x) antigen in MKN45 gastric carcinoma cells and evaluated the effect of SLe(x) overexpression in cancer cell behavior both in vitro and in vivo using the chicken chorioallantoic membrane (CAM) model. The activation of tyrosine kinase receptors and their downstream molecular targets was also addressed. Our results showed that the expression of ST3GAL4 in MKN45 gastric cancer cells leads to the synthesis of SLe(x) antigens and to an increased invasive phenotype both in vitro and in the in vivo CAM model. Analysis of phosphorylation of tyrosine kinase receptors showed a specific increase in c-Met activation. The characterization of downstream molecular targets of c-Met activation, involved in the invasive phenotype, revealed increased phosphorylation of FAK and Src proteins and activation of Cdc42, Rac1 and RhoA GTPases. Inhibition of c-Met and Src activation abolished the observed increased cell invasive phenotype. In conclusion, the expression of ST3GAL4 leads to SLe(x) antigen expression in gastric cancer cells which in turn induces an increased invasive phenotype through the activation of c-Met, in association with Src, FAK and Cdc42, Rac1 and RhoA GTPases activation.

Unique gangliosides synthesized in vitro by sialyltransferases from marine bacteria and their characterization: ganglioside synthesis by bacterial sialyltransferases

On the basis of the results outlined in our previous report, bacterial sialyltransferases (ST) from marine sources were further characterized using glycosphingolipids (GSL), especially ganglio-series GSLs, based on the enzymatic characteristics and kinetic parameters obtained by Line weaver-Burk plots. Among them, GA1 and GA2 were found to be good substrates for these unique STs. Thus, new gangliosides synthesized by α2-3 and α2-6STs were structurally characterized by several analytical procedures. The ganglioside generated by the catalytic activity of α2-3ST was identified as GM1b. On the other hand, when enzyme reactions by α2-6STs were performed using substrates GA2 and GA1, very unique gangliosides were generated. The structures were identified as NeuAcα2-6GalNAcβ1-4Galβ1-4Glcβ-Cer and NeuAcα2-6Galβ1-3GalNAcβ1-4Galβ1-4Glcβ-Cer, respectively. The synthesized ganglioside NeuAcα2-6GalNAcβ1-4Galβ1-4Glcβ-Cer showed binding activity to the influenza A virus {A/Panama/2007/99 (H3N2)} at a similar level to purified sialyl(α2-3)paragloboside (S2-3PG) and sialyl(α2-6)paragloboside (S2-6PG) from mammalian sources. The evidence suggests that these STs have unique features, including substrate specificities restricted not only to lacto-series but also to ganglio-series GSLs, as well as catalytic potentials for ganglioside synthesis. This evidence demonstrates that effective in vitro ganglioside synthesis could be a valuable tool for selectively synthesizing sialic acid (Sia) modifications, thereby preparing large-scale gangliosides and permitting the exploration of unknown functions.

Reversibility of membrane N-glycome of HeLa cells upon treatment with epigenetic inhibitors

Glycans are essential regulators of protein function and are now in the focus of research in many physiological and pathophysiological processes. There are numerous modes of regulating their biosynthesis, including epigenetic mechanisms implicated in the expression of glyco-genes. Since N-glycans located at the cell membrane define intercellular communication as well as a cellular response to a given environment, we developed a method to preferentially analyze this fraction of glycans. The method is based on incorporation of living cells into polyacrylamide gels, partial denaturation of membrane proteins with 3 M urea and subsequent release of N-glycans with PNGase F followed by HPLC analysis. Using this newly developed method, we revealed multiple effects of epigenetic inhibitors Trichostatin A, sodium butyrate and zebularine on the composition of N-glycans in human cells. The induced changes were found to be reversible after inhibitor removal. Given that many epigenetic inhibitors are currently explored as a therapeutic strategy in treatment of cancer, wherein surface glycans play an important role, the presented work contributes to our understanding of their efficiency in altering the N-glycan profile of cancer cells in culture.

Inhibitions of several antineoplastic drugs on serum sialic Acid levels in mice bearing tumors

Six murine tumors, including ascetic tumors HepA, EC, P388 leukemia, S180 and solid tumor S180, and Lewis lung carcinoma, were employed in this work. The free sialic acid concentrations in both blood and ascites were measured in tumor-bearing mice. The results showed that the content of sialic acids in blood was increased in tumor growth and certain tumor types. Higher sialic acid content was observed in ascites than that present in blood. The influence of antineoplastic agents (vincristine, thiotepa, adriamycin, probimane, cisplatin, oxalysine, cortisone, nitrogen mustard, lycobetaine, Ara-C, harringtonine, and cyclophosphamide) on the content of sialic acids in mice blood bearing solid tumors of either S180 or Lewis lung carcinoma was observed. Different inhibitions of antineoplastic drugs on both tumor growth and serum sialic acid levels in mice bearing tumors were found. Among these antineoplastic drugs, probimane, cisplatin, nitrogen mustard, and lycobetaine were able to decrease the serum sialic acid levels in mice bearing tumors. Since these four antineoplastic drugs are all DNA chelating agents, it was proposed that the inhibition of tumor sialic acids by these drugs might be through the DNA template via two ways. Since we have found no effect of antineoplastic drugs on serum sialic acid levels in normal mice, this suggests that the inhibition of antineoplastic drugs on sialic acids is by tumor involvement.

Lectin histochemistry to detect altered glycosylation in cells and tissues

Lectins are naturally occurring carbohydrate-binding molecules. A very wide range of purified lectins are commercially available which exhibit a diversity of carbohydrate-binding preferences. They can be used in the laboratory to detect carbohydrate structures on, or in, cells and tissues in much the same way that purified antibodies can be employed to detect cell- or tissue-bound antigens using immunocytochemistry. As lectins can distinguish subtle alterations in cellular glycosylation, they are helpful in exploring the glycosylation changes that attend both transformation to malignancy and tumour progression. In this chapter, methodologies are given for appropriate preparation of many types of cell and tissue preparations, including cells cultured on coverslips (which can be used for live-cell imaging), cell smears, and frozen (cryostat) and fixed, paraffin wax-embedded tissue sections. Heat- and enzyme-based carbohydrate retrieval methods are covered. Basic detection methods, which can be readily adapted to the researcher's needs, are given for direct (labelled lectin), simple indirect (labelled secondary antibody directed against the lectin), and avidin-biotin (biotinylated lectin) and avidin-biotin complex. The use of both the enzyme label, horseradish peroxidase, and fluorescent labels is considered.