The high affinity selectin glycan ligand C2-O-sLex and mRNA transcripts of the core 2 beta-1,6-N-acetylglucosaminyltransferase (C2GnT1) gene are highly expressed in human colorectal adenocarcinomas

Bisimidazolium Salt Glycosyltransferase Inhibitors Suppress Hepatocellular Carcinoma Progression In Vitro and In Vivo

Hepatocellular carcinoma is a leading cause of cancer death, and the disease progression has been related to glycophenotype modifications. Previously synthesized bisimidazolium salts (C20 and C22) have been shown to selectively inhibit the activity of glycosyltransferases in cultured cancer cell homogenates. The current study investigated the anticancer effects of C20/C22 and the possible pathways through which these effects are achieved. The therapeutic value of C20/C22 in terms of inhibiting cancer cell proliferation, metastasis, and angiogenesis, as well as inducing apoptosis, were examined with hepatic cancer cell line HepG2 and a xenograft mouse model. C20/C22 treatment downregulated the synthesis of SLex and Ley sugar epitopes and suppressed selectin-mediated cancer cell metastasis. C20/C22 inhibited HepG2 proliferation, induced cell-cycle arrest, increased intracellular ROS level, led to ER stress, and eventually induced apoptosis through the intrinsic pathway. Furthermore, C20/C22 upregulated the expressions of death receptors DR4 and DR5, substantially increasing the sensitivity of HepG2 to TRAIL-triggered apoptosis. In vivo, C20/C22 effectively inhibited tumor growth and angiogenesis in the xenograft mouse model without adverse effects on major organs. In summary, C20 and C22 are new promising anti-hepatic cancer agents with multiple mechanisms in controlling cancer cell growth, metastasis, and apoptosis, and they merit further development into anticancer drugs.

Spatial structure governs the mode of tumour evolution

Characterizing the mode-the way, manner or pattern-of evolution in tumours is important for clinical forecasting and optimizing cancer treatment. Sequencing studies have inferred various modes, including branching, punctuated and neutral evolution, but it is unclear why a particular pattern predominates in any given tumour. Here we propose that tumour architecture is key to explaining the variety of observed genetic patterns. We examine this hypothesis using spatially explicit population genetics models and demonstrate that, within biologically relevant parameter ranges, different spatial structures can generate four tumour evolutionary modes: rapid clonal expansion, progressive diversification, branching evolution and effectively almost neutral evolution. Quantitative indices for describing and classifying these evolutionary modes are presented. Using these indices, we show that our model predictions are consistent with empirical observations for cancer types with corresponding spatial structures. The manner of cell dispersal and the range of cell-cell interactions are found to be essential factors in accurately characterizing, forecasting and controlling tumour evolution.

Establishment of an antibody specific for AMIGO2 improves immunohistochemical evaluation of liver metastases and clinical outcomes in patients with colorectal cancer

Instruction

The human amphoterin-induced gene and open reading frame (AMIGO) was identified as a novel cell adhesion molecule of type I transmembrane protein. AMIGO2 is one of three members of the AMIGO family (AMIGO1, 2, and 3), and the similarity between them is approximately 40% at the amino acid level. We have previously shown that AMIGO2 functions as a driver of liver metastasis. Immunohistochemical analysis of AMIGO2 expression in colorectal cancer (CRC) using a commercially available anti-AMIGO2 mouse monoclonal antibody clone sc-373699 (sc mAb) correlated with liver metastasis and poor prognosis. However, the sc mAb was found to be cross-reactive with all three molecules in the AMIGO family.

Methods

We generated a rat monoclonal antibody clone rTNK1A0012 (rTNK mAb) for human AMIGO2. The rTNK mAb was used to re-evaluate the association between AMIGO2 expression and liver metastases/clinical outcomes using the same CRC tissue samples previously reported with sc mAb.

Results

Western blot analysis revealed that a rTNK mAb was identified as being specific for AMIGO2 protein and did not cross-react with AMIGO1 and AMIGO3. The rTNK mAb and sc mAb showed higher AMIGO2 expression, which correlates with a high frequency of liver metastases (65.3% and 47.5%, respectively), while multivariate analysis showed that AMIGO2 expression was an independent prognostic factor for liver metastases (p = 7.930E-10 and p = 1.707E-5). The Kaplan-Meier analyses showed that the rTNK mAb (p = 0.004), but not sc mAb (p = 0.107), predicted worse overall survival in patients with high AMIGO2 expression. The relationship between AMIGO2 expression and poor disease-specific survival showed a higher level of significance for rTNK mAb (p = 0.00004) compared to sc mAb (p = 0.001).

Conclusions

These results indicate that the developed rTNK1A0012 mAb is an antibody that specifically recognizes AMIGO2 by immunohistochemistry and can be a more reliable and applicable method for the diagnostic detection of liver metastases and worse prognosis in patients with high AMIGO2-expressing CRC.

Characterization of tumor-associated MUC1 and its glycans expressed in mucoepidermoid carcinoma

Mucoepidermoid carcinoma (MEC) is one of the most frequently misdiagnosed tumors. Glycans are modulated by malignant transformation. Mucin 1 (MUC1) is a mucin whose expression is upregulated in various tumors, including MEC, and it has previously been investigated as a diagnostic and prognostic tumor marker. The present study aimed to reveal the differences in the mucin glycans between MEC and normal salivary glands (NSGs) to discover novel diagnostic markers. Soluble fractions of salivary gland homogenate prepared from three MEC salivary glands and 7 NSGs were evaluated. Mucins in MEC and NSGs were separated using supported molecular matrix electrophoresis, and stained with Alcian blue and monoclonal antibodies. The glycans of the separated mucins were analyzed by mass spectrometry. MUC1 was found in MEC but not in NSGs, and almost all glycans of MUC1 in MEC were sialylated, whereas the glycans of mucins in NSGs were less sialylated. The core 2 type glycans, (Hex)₂(HexNAc)₂(NeuAc)₁ and (Hex)₂(HexNAc)₂(NeuAc)₂, were found to be significantly abundant glycans of MUC1 in MEC. MEC markedly produced MUC1 modified with sialylated core 2 glycans. These data were obtained from the soluble fractions of salivary gland homogenates. These findings provide a basis for the utilization of MUC1 as a serum diagnostic marker for the preoperative diagnosis of MEC.

A Systematic Review on the Implications of O-linked Glycan Branching and Truncating Enzymes on Cancer Progression and Metastasis

Glycosylation is the most commonly occurring post-translational modifications, and is believed to modify over 50% of all proteins. The process of glycan modification is directed by different glycosyltransferases, depending on the cell in which it is expressed. These small carbohydrate molecules consist of multiple glycan families that facilitate cell-cell interactions, protein interactions, and downstream signaling. An alteration of several types of O-glycan core structures have been implicated in multiple cancers, largely due to differential glycosyltransferase expression or activity. Consequently, aberrant O-linked glycosylation has been extensively demonstrated to affect biological function and protein integrity that directly result in cancer growth and progression of several diseases. Herein, we provide a comprehensive review of several initiating enzymes involved in the synthesis of O-linked glycosylation that significantly contribute to a number of different cancers.

Gene Selection for the Discrimination of Colorectal Cancer

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer worldwide. Cancer discrimination is a typical application of gene expression analysis using a microarray technique. However, microarray data suffer from the curse of dimensionality and usual imbalanced class distribution between the majority (tumor samples) and minority (normal samples) classes. Feature gene selection is necessary and important for cancer discrimination.

OBJECTIVES

To select feature genes for the discrimination of CRC.

METHODS

We improve the feature selection algorithm based on differential evolution, DEFSw by using RUSBoost classifier and weight accuracy instead of the common classifier and evaluation measure for selecting feature genes from imbalance data. We firstly extract differently expressed genes (DEGs) from the CRC dataset of the TCGA and then select the feature genes from the DEGs using the improved DEFSw algorithm. Finally, we validate the selected feature gene sets using independent datasets and retrieve the cancer related information for these genes based on text mining through the Coremine Medical online database.

RESULTS

We select out 16 single-gene feature sets for colorectal cancer discrimination and 19 single-gene feature sets only for colon cancer discrimination.

CONCLUSIONS

In summary, we find a series of high potential candidate biomarkers or signatures, which can discriminate either or both of colon cancer and rectal cancer with high sensitivity and specificity.

Simple sugars to complex disease--mucin-type O-glycans in cancer

Mucin-type O-glycans are a class of glycans initiated with N-acetylgalactosamine (GalNAc) α-linked primarily to Ser/Thr residues within glycoproteins and often extended or branched by sugars or saccharides. Most secretory and membrane-bound proteins receive this modification, which is important in regulating many biological processes. Alterations in mucin-type O-glycans have been described across tumor types and include expression of relatively small-sized, truncated O-glycans and altered terminal structures, both of which are associated with patient prognosis. New discoveries in the identity and expression of tumor-associated O-glycans are providing new avenues for tumor detection and treatment. This chapter describes mucin-type O-glycan biosynthesis, altered mucin-type O-glycans in primary tumors, including mechanisms for structural changes and contributions to the tumor phenotype, and clinical approaches to detect and target altered O-glycans for cancer treatment and management.

Glycosylation characteristics of colorectal cancer

Glycans on proteins and lipids are known to alter with malignant transformation. The study of these may contribute to the discovery of biomarkers and treatment targets as well as understanding of cancer biology. We here describe the change of glycosylation specifically defining colorectal cancer with view on N-glycans, O-glycans, and glycosphingolipid glycans in colorectal cancer cells and tissues as well as patient sera. Glycan alterations observed in colon cancer include increased β1,6-branching and correlating higher abundance of (poly-)N-acetyllactosamine extensions of N-glycans as well as an increase in (truncated) high-mannose type glycans, while bisected structures decrease. Colorectal cancer-associated O-glycan changes are predominated by reduced expression of core 3 and 4 glycans, whereas higher levels of core 1 glycans, (sialyl) T-antigen, (sialyl) Tn-antigen, and a generally higher density of O-glycans are observed. Specific changes for glycosphingolipid glycans are lower abundances of disialylated structures as well as globo-type glycosphingolipid glycans with exception of Gb3. In general, alterations affecting all discussed glycan types are increased sialylation, fucosylation as well as (sialyl) Lewis-type antigens and type-2 chain glycans. As a consequence, interactions with glycan-binding proteins can be affected and the biological function and cellular consequences of the altered glycosylation with regard to tumorigenesis, metastasis, modulation of immunity, and resistance to antitumor therapy will be discussed. Finally, analytical approaches aiding in the field of glycomics will be reviewed with focus on binding assays and mass spectrometry.

Hill CA, Walcheck B, Brooks JD. Increased expression of GCNT1 is associated with altered O-glycosylation of PSA, PAP, and MUC1 in human prostate cancers

BACKGROUND

Protein glycosylation is a common posttranslational modification and glycan structural changes have been observed in several malignancies including prostate cancer. We hypothesized that altered glycosylation could be related to differences in gene expression levels of glycoprotein synthetic enzymes between normal and malignant prostate tissues.

METHODS

We interrogated prostate cancer gene expression data for reproducible changes in expression of glycoprotein synthetic enzymes. Over-expression of GCNT1 was validated in prostate samples using RT-PCR. ELISA was used to measure core 2 O-linked glycan sialyl Lewis X (sLe(x) ) of prostate specific antigen (PSA), Mucin1 (MUC1), and prostatic acidic phosphatase (PAP) proteins.

RESULTS

A key glycosyltransferase, GCNT1, was consistently over-expressed in several prostate cancer gene expression datasets. RT-PCR confirmed increased transcript levels in cancer samples compared to normal prostate tissue in fresh-frozen prostate tissue samples. ELISA using PSA, PAP, and MUC1 capture antibodies and a specific core 2 O-linked sLe(x) detection antibody demonstrated elevation of this glycan structure in cancer compared to normal tissues for MUC1 (P = 0.01), PSA (P = 0.03) and near significant differences in PAP sLe(x) levels (P = 0.06). MUC1, PSA and PAP protein levels alone were not significantly different between paired normal and malignant prostate samples.

CONCLUSIONS

GCNT1 is over-expressed in prostate cancer and is associated with higher levels of core 2 O-sLe(x) in PSA, PAP and MUC1 proteins. Alterations of O-linked glycosylation could be important in prostate cancer biology and could provide a new avenue for development of prostate cancer specific glycoprotein biomarkers.

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.

Lipopolysaccharide-induced toll-like receptor 4 signaling enhances the migratory ability of human esophageal cancer cells in a selectin-dependent manner

BACKGROUND

Esophageal cancer is an aggressive malignancy, and emerging data suggest that postoperative infections may promote cancer progression. Systemic exposure to lipopolysaccharide (LPS), a Gram-negative bacterial antigen involved in such infections, has been shown to increase cancer cell adhesion to the hepatic sinusoids in vivo. We investigated the direct impact of LPS on the migratory ability of esophageal cancer cells via the LPS receptor toll-like receptor 4 (TLR4).

METHODS

Human esophageal squamous carcinoma cell lines and immortalized normal esophageal mucosa cells were tested for TLR4 surface expression by reverse transcription polymerase chain reaction (RT-PCR) and flow cytometry. TLR4 signaling in response to LPS stimulation was tested in these cells by measuring p38 MAP kinase phosphorylation on Western blot. The impact of TLR4 signaling was measured by static adhesion assays in vitro and on early in vivo migration by intravital microscopy of the liver.

RESULTS

Upon LPS stimulation, phosphorylation of p38 was detected in the human esophageal cancer cells HKESC-2. Also, LPS-stimulated HKESC-2 cells showed a twofold increased adhesion to fibronectin and to hepatic sinusoidal endothelium. These effects were abolished by TLR4 inhibition using the small-molecule inhibitor eritoran. Adhesion to fibronectin and hepatic sinusoidal endothelium was also diminished by blockade of p38 phosphorylation and inhibitors of selectin-selectin ligand binding.

CONCLUSION

LPS can increase the migratory ability of human esophageal cancer cells by increasing their adhesive properties through TLR4 signaling and selectin ligands. TLR4, p38, and selectin blockade may therefore prove to be a new therapeutic strategy for this aggressive malignancy.

Immunohistochemical expression of core 2 β1,6-N-acetylglucosaminyl transferase 1 (C2GnT1) in endometrioid-type endometrial carcinoma: a novel potential prognostic factor

AIMS

It has been reported that the expression of core 2 β1,6-N-acetylglucosaminyl transferase 1 (C2GnT1), which synthesizes the core 2 branching structure on O-glycans, may be associated with the biological aggressiveness of tumour cells. Therefore, the aim of this study was to examine the relationship between the expression of C2GnT1 and clinicopathological parameters of patients with endometrial carcinoma.

METHODS AND RESULTS

The immunohistochemical expression of C2GnT1 was examined in 84 cases of endometrioid-type endometrial carcinoma, 15 cases of endometrial hyperplasia, and 30 normal endometria. The staining intensity was reported according to a positivity index (PI, full score 100), calculated from the percentage of positive cells. The expression of C2GnT1 was significantly higher in endometrial carcinoma (PI = 8.31 ± 15.29) than in normal endometrium (PI = 0.52 ± 1.24) (P < 0.0005). In carcinomas, the PI was higher in high-grade or advanced-stage tumours, but not significantly. Topologically, C2GnT1 was strongly expressed at sites of deep myometrial invasion. In addition, patients with C2GnT1 overexpression (PI ≥ 10) had significantly shorter survival (P < 0.0005). Multivariable analysis also indicated that C2GnT1 overexpression was an independent prognostic factor (P = 0.017).

CONCLUSIONS

C2GnT1 appears to be involved in the biological aggressiveness of endometrial carcinoma. C2GnT1 might become a novel prognostic factor for endometrial carcinoma.

Acceptor specificities and selective inhibition of recombinant human Gal- and GlcNAc-transferases that synthesize core structures 1, 2, 3 and 4 of O-glycans

BACKGROUND

Modifications of proteins by O-glycosylation determine many of the properties and functions of proteins. We wish to understand the mechanisms of O-glycosylation and develop inhibitors that could affect glycoprotein functions and alter cellular behavior.

METHODS

We expressed recombinant soluble human Gal- and GlcNAc-transferases that synthesize the O-glycan cores 1 to 4 and are critical for the overall structures of O-glycans. We determined the properties and substrate specificities of these enzymes using synthetic acceptor substrate analogs. Compounds that were inactive as substrates were tested as inhibitors.

RESULTS

Enzymes significantly differed in their recognition of the sugar moieties and aglycone groups of substrates. Core 1 synthase was active with glycopeptide substrates but GlcNAc-transferases preferred substrates with hydrophobic aglycone groups. Chemical modifications of the acceptors shed light on enzyme-substrate interactions. Core 1 synthase was weakly inhibited by its substrate analog benzyl 2-butanamido-2-deoxy-α-d-galactoside while two of the three GlcNAc-transferases were selectively and potently inhibited by bis-imidazolium salts which are not substrate analogs.

CONCLUSIONS

This work delineates the distinct specificities and properties of the enzymes that synthesize the common O-glycan core structures 1 to 4. New inhibitors were found that could selectively inhibit the synthesis of cores 1, 2 and 3 but not core 4.

GENERAL SIGNIFICANCE

These studies help our understanding of the mechanisms of action of enzymes critical for O-glycosylation. The results may be useful for the re-engineering of O-glycosylation to determine the roles of O-glycans and the enzymes critical for O-glycosylation, and for biotechnology with potential therapeutic applications.

Leveraging fluorinated glucosamine action to boost antitumor immunity

N-acetyllactosaminyl glycans are key regulators of the vitality and effector function of antitumor T cells. When galectin-1 (Gal-1) binds N-acetyllactosamines on select membrane glycoproteins on antitumor T cells, these cells either undergo apoptosis or become immunoregulatory. Methods designed to antagonize expression or function of these N-acetyllactosamines on N-glycans and O-glycans have thus intensified. Since tumors can produce an abundance of Gal-1, Gal-1 is considered a critical factor for protecting tumor cells from T cell-mediated antitumor activity. Recent efforts have capitalized on the anti-N-acetyllactosamine action of fluorinated glucosamines to treat antitumor T cells, resulting in diminished Gal-1-binding and higher antitumor T cell levels. In this perspective, the prospect of fluorinated glucosamines in eliminating N-acetyllactosamines on antitumor T cells to boost antitumor immunity is presented.

Glycosylation potential of human prostate cancer cell lines

Altered glycosylation is a universal feature of cancer cells and altered glycans can help cancer cells escape immune surveillance, facilitate tumor invasion, and increase malignancy. The goal of this study was to identify specific glycoenzymes, which could distinguish prostate cancer cells from normal prostatic cells. We investigated enzymatic activities and gene expression levels of key glycosyl- and sulfotransferases responsible for the assembly of O- and N-glycans in several prostatic cells. These cells included immortalized RWPE-1 cells derived from normal prostatic tissues, and prostate cancer cells derived from metastasis in bone (PC-3), brain (DU145), lymph node (LNCaP), and vertebra (VCaP). We found that all cells were capable of synthesizing complex N-glycans and O-glycans with the core 1 structure, and each cell line had characteristic biosynthetic pathways to modify these structures. The in vitro measured activities corresponded well to the mRNA levels of glycosyltransferases and sulfotransferases. Lectin and antibody binding to whole cells supported these results, which form the basis for the development of tumor cell-specific targeting strategies.

Selectins and Associated Adhesion Proteins in Inflammatory disorders

Inflammation is defined as the normal response of living tissue to injury or infection. It is important to emphasize two components of this definition. First, that inflammation is a normal response and, as such, is expected to occur when tissue is damaged. Infact, if injured tissue does not exhibit signs of inflammation this would be considered abnormal and wounds and infections would never heal without inflammation. Secondly, inflammation occurs in living tissue, hence there is need for an adequate blood supply to the tissues in order to exhibit an inflammatory response. The inflammatory response may be triggered by mechanical injury, chemical toxins, and invasion by microorganisms, and hypersensitivity reactions. Three major events occur during the inflammatory response: the blood supply to the affected area is increased substantially, capillary permeability is increased, and leucocytes migrate from the capillary vessels into the surrounding interstitial spaces to the site of inflammation or injury. The inflammatory response represents a complex biological and biochemical process involving cells of the immune system and a plethora of biological mediators. Cell-to-cell communication molecules such as cytokines play an extremely important role in mediating the process of inflammation. Inflammation and platelet activation are critical phenomena in the setting of acute coronary syndromes. An extensive exposition of this complex phenomenon is beyond the scope of this article (Rankin 2004).

Differential glycosylation of MUC1 and CEACAM5 between normal mucosa and tumour tissue of colon cancer patients

Altered glycosylation in epithelial cancers may play an important role in tumour progression, as it may affect tumour cell migration and antigen presentation by antigen presenting cells. We specifically characterise the glycosylation patterns of two tumour antigens that are highly expressed in cancer tissue and often detected in their secreted form in serum: the epithelial mucin MUC1 and carcinoembryonic antigen (CEA, also called CEACAM5). We analysed 48 colorectal cancer patients, comparing normal colon and tumour epithelium within each patient. Lectin binding was studied by a standardised CEA/MUC1 capture ELISA, using several plant lectins, and the human C-type lectins MGL and DC-SIGN, and Galectin-3. Peanut agglutinin (PNA) bound to MUC1 from tumour tissue in particular, suggests increased expression of the Thomsen-Friedenreich antigen (TF-antigen) (Core 1, Galβ1-3GalNAc-Ser/Thr). Only small amounts of Tn-antigen (GalNAcα-Ser/Thr) expression was observed, but the human C-type lectin MGL showed increased binding to tumour-associated MUC1. Furthermore, sialylation was greatly enhanced. In sharp contrast, tumour-associated CEA (CEACAM5) contained high levels of the blood-group related carbohydrates, Lewis X and Lewis Y. This correlated strongly with the interaction of the human C-type lectin DC-SIGN to tumour-associated CEA, suggesting that CEA can be recognized and taken up by antigen presenting cells. In addition, increased mannose expression was observed and branched N-glycans were prominent, and this correlated well with human Galectin-3 binding. These data demonstrate that individual tumour antigens contain distinct glycan structures associated with cancer and, since glycans affect cellular interactions with its microenvironment, this may have consequences for progression of the disease.

Highly glycosylated tumour antigens: interactions with the immune system

A common phenotypic change in cancer is a dramatic transformation of cellular glycosylation. Functional studies of particular tumour-associated oligosaccharides are difficult to interpret conclusively, but carbohydrate-binding proteins are likely to contribute to progression of the tumour. This review discusses the potential role of CLRs (C-type lectin receptors), expressed by antigen-presenting cells of the immune system, in tumour recognition and immune modulation. Studies in recent years have provided significant insight into the immunomodulatory function of CLR during infections, but their role in cancer remains elusive; some strongly bind tumour cells and antigens, indicating participation in malignancy. The potential to use recombinant CLR as diagnostic tools will also be discussed.

Neutrophil interactions with sialyl Lewis X on human nonsmall cell lung carcinoma cells regulate invasive behavior

BACKGROUND

The carbohydrate sialyl Lewis X (sLeX) is expressed on leukocytes and carcinoma cells and binds to selectins during inflammatory processes and early metastasis. Synthesis of sLeX depends on activity of enzymes, including α(1,3/1,4) fucosyltransferase (FucT-III). Tumor necrosis factor-α (TNF-α) up-regulates FucT-III, resulting in increased sLeX in the airways of patients with respiratory disease; however, the mechanisms that regulate sLeX in the inflammatory tumor microenvironment are not well understood.

METHODS

The authors stably transfected human lung carcinoma cell lines with the FucT-III gene and exposed them to TNF-α to investigate its role in regulation of sLeX expression and selectin-binding ability using semiquantitative real-time polymerase chain reaction and flow cytometry. Cytokine expression was examined in transfected cells using chemiluminescent arrays and enzyme-linked immunosorbent assays, and invasion was studied using Matrigel assays and alterations in morphology. Human lung tissue arrays were analyzed for immunohistochemical detection of sLeX and neutrophils.

RESULTS

Stimulation of FucT-III-transfected cells with recombinant human (rh) TNF-α up-regulated sLeX expression and increased E-selectin binding. Transfected cells secreted high levels of interleukin 8, growth-regulated oncogene-α, and mast cell proteinase-1. Cells exposed to rhTNF-α, neutrophil-conditioned media, and cultures with a 5:1 ratio of neutrophils to cancer cells had significantly increased sLeX expression and invasiveness and underwent nonadherent morphologic changes. In lung carcinomas, but not in normal lung tissues, 71% of tumors were highly positive for sLeX expression in areas of increased neutrophil infiltration.

CONCLUSIONS

The current results indicated that neutrophils may be recruited to areas of FucT-III activity and sLeX expression in lung carcinomas to enhance the invasive and metastatic potential of lung cancer cells.

Pathobiology of colorectal cancer hepatic metastases with an emphasis on prognostic factors

Colorectal cancer is the second leading cause of cancer related death in the United States. The majority of these deaths are due to metastasis, with the liver easily accounting as the most common site of deposit. While there are multiple steps in the CRC hepatic metastatic cascade, this review attempts to summarize the different processes involved, focusing on the most recent discoveries, as well as the associated effects in relation to prognosis.

C2-O-sLeX glycoproteins are E-selectin ligands that regulate invasion of human colon and hepatic carcinoma cells

Similar to mechanisms of recruitment of activated leukocytes to inflamed tissues, selectins mediate adhesion and extravasation of circulating cancer cells. Our objective was to determine whether sialyl Lewis X modified core 2 O-glycans (C2-O-sLe^X) present on colon and hepatic carcinoma cells promote their adhesion and invasion. We examined membrane expression of C2-O-sLe^X, selectin binding, invasion of human colon and hepatic carcinoma cell lines, and mRNA levels of alpha-2,3 fucosyltransferase (FucT-III) and core 2 beta-1,6 N-acetylglucosaminyltransferase (C2GnT1) genes, necessary for C2-O-sLe^X synthesis, by quantitative reverse-transcriptase (RT) PCR. Synthesis of core 2 branched O-glycans decorated by sLe^X is dependent on C2GnT1 function and thus we determined enzyme activity of C2GnT1. The cell lines that expressed C2GnT1 and FucT-III mRNA by quantitative RT-PCR were highly positive for C2-O-sLe^X by flow cytometry, and colon carcinoma cells possessed highly active C2GnT1 enzyme. Cells bound avidly to E-selection but not to P- and L-selectin. Gene knock-down of C2GnT1 in colon and hepatic carcinoma cells using short hairpin RNAs (shRNA) resulted in a 40–90% decrease in C2-O-sLe^X and a 30–50% decrease in E-selectin binding compared to control cells. Invasion of hepatic and colon carcinoma cells containing C2GnT1 shRNA was significantly reduced compared to control cells in Matrigel assays and C2GnT1 activity was down-regulated in the latter cells. The sLe^X epitope was predominantly distributed on core 2 O-glycans on colon and hepatic carcinoma cells. Our findings indicate that C2GnT1 gene expression and the resulting C2-O-sLe^X carbohydrates produced mediate the adhesive and invasive behaviors of human carcinomas which may influence their metastatic potential.

Sialylated Lewis x antigen bearing glycoproteins in human plasma

Recent studies have shown that antibodies targeting Lewis x (Le(x)) antigen are a valuable tool in the isolation and identification of glycoproteins in plasma. A focus of this study was to determine whether sialylated Lewis x (sLe(x)) antigen carrying glycoproteins occur in human plasma and whether an antibody targeting this antigen could be used to isolate and identify glycoproteins bearing this antigen. An additional objective was to determine the degree to which proteins conjugated to Le(x) and sLe(x) antigens are similar in structure. A specific anti-sLe(x) antibody (anti-sLe(x)Ab), CHO-131, immobilized in an immunoaffinity column was used to select a set of specific sLe(x) bearing proteins from human plasma, after which they were identified by either of two analytical strategies. One approach was to further resolve the affinity selected proteins by reversed phase chromatography (RPC), tryptic digest the RPC fractions, and identify peptide fragments by MALDI-MS/MS. The second was to tryptic digest the affinity selected protein fraction, further resolve the tryptic fragments by RPC, and identify peptides from RPC fractions by MALDI-MS/MS. Histidine-rich glycoprotein, plasminogen, apolipoprotein A-I, vitronectin, proteoglycan-4, clusterin, Ig gamma-2 chain C region, Ig mu chain C region, and interalpha-trypsin inhibitor heavy chain H4 were found to change three folds or more in association with breast cancer. Fifty percent of the glycoproteins carrying either sLe(x) antigen from CHO-131 selection, Le(x) antigen from selection with TG-1 antibody, or both were found to be changed three folds or more in concentration in breast cancer plasma relative to controls.

Hill CA. The Novel Carbohydrate Tumor Antigen C2-O-sLex Is Upregulated in Canine Gastric Carcinomas

Sialyl Lewis x–modified core 2 branched O-glycans (C2-O-sLex) on human leukocytes mediate much higher-affinity adhesion to selectins on activated vascular endothelium than does sialyl Lewis x on other structures. In some canine and human carcinomas, high expression of sLex-decorated carbohydrates has been associated with metastasis and, in humans, a poor prognosis, but detection in canine gastric carcinomas is unreported. The authors hypothesized that these carbohydrates are highly expressed in more malignant types of canine gastric carcinomas, they promote metastasis, and they are associated with a poorer prognosis for dogs. The objectives were to determine the presence and importance of C2-O-sLex expression in canine gastric carcinomas. Routine histological sections of 16 canine gastric carcinomas were categorized on the basis of 3 classification schemes: World Health Organization, Lauren, and Goseki. Serial sections were stained with antibodies directed against C2-O-sLex (CHO-131 monoclonal antibody), cytokeratin (Lu-5 monoclonal antibody), and stains to detect neutral and acid mucins (periodic acid–Schiff and alcian blue). Whereas normal gastric mucosal epithelial cells were negative for C2-O-sLex, 56% of the tumors examined were positive for C2-O-sLex. Importantly, the majority of more poorly differentiated tumor types had more numerous and larger intensely stained areas of C2-O-sLex expression compared with moderate to well-differentiated tumor types. Signet ring–type carcinomas had markedly higher distribution and intensity of periodic acid–Schiff and alcian blue staining than did tubular carcinomas. These findings suggest that C2-O-sLex is a tumor-associated antigen that may play a role in the invasiveness and metastatic potential of certain types of canine gastric carcinomas.

Cutaneous lymphocyte-associated antigen (CLA) T cells up-regulate P-selectin ligand expression upon their activation

Memory T cells expressing CLA occur in humans and accumulate in normal and inflamed skin. These cells uniformly bind to the vascular adhesion molecule E-selectin, yet only a subset binds to P-selectin. The latter cells are distinguished by the mAb CHO-131, and are enriched in psoriasis lesions. Activated T cells up-regulate CLA expression, but little is currently known about their binding to P-selectin. We observed that CLA(+) CD4(+) T cells derived from stimulated naive T cells uniformly express the CHO-131 epitope. This occurred as well upon the restimulation of memory CLA(+) CD4(+) T cells. The latter cells also expressed higher levels of PSGL-1 modified by P-selectin glycan ligands; C2GlcNAcT-1 mRNA, a glycosyltransferase critical for such glycan synthesis; and more uniformly bound to P-selectin. Our findings thus indicate that unlike memory CLA(+) CD4(+) T cells, when activated these cells can broadly bind to P-selectin, suggesting a more diverse tissue trafficking capacity.