ELAM-1 mediates cell adhesion by recognition of a carbohydrate ligand, sialyl-Lex

Selectin-blocking semisynthetic sulfated polysaccharides as promising anti-inflammatory agents

Selectin-induced leucocytes rolling along the endothelial surface of blood vessels initiate a complex adhesion cascade, which is an essential step in the cellular immune response. Consequently, blocking the binding between the selectins and their ligands represents a promising strategy for suppressing pathological inflammatory reactions. This study describes the effects of an unfractionated heparin and a low-molecular-weight heparin and a series of structurally well-defined semisynthetic glucan sulfates on selectin-mediated cell-rolling with respect to inhibition. To simulate the blood flow characteristics of postcapillary venules, the rolling experiments were performed in a dynamic-flow-chamber system with immobilized selectins and selectin ligand-carrying U937 cells. The influence of the test compounds on cell rolling was measured by the percentage of adherent cells after a certain flow time and the velocity of the rolling cells. Whereas the test compounds displayed no inhibitory effect on E-selectin-mediated cell rolling, they efficiently blocked the rolling induced by P-selectin. The glucan sulfates were much more active than either unfractionated heparin or low-molecular-weight heparin, or the standard inhibitor Sialyl Lewis(X). Their inhibitory potency turned out to be strongly dependent on various structural parameters, such as sulfation pattern and molecular weight. In conclusion, the semisysnthetic glucan sulfates represent promising candidates in the development of selectin blocking agents.

The structural biology of type I viral membrane fusion

The fusion of viral membranes with target-cell membranes is an essential step in the entry of enveloped viruses into cells, and recent X-ray structures of paramyxoviral envelope proteins have provided new insights into protein-mediated plasma-membrane fusion. Here, we review our understanding of the structural transitions that are involved in this fusion pathway, compare it to our understanding of influenza virus membrane fusion, and discuss the implications for retroviral membrane fusion.

Extended core 1 and core 2 branched O-glycans differentially modulate sialyl Lewis X-type L-selectin ligand activity

It has been established that sialyl Lewis x in core 2 branched O-glycans serves as an E- and P-selectin ligand. Recently, it was discovered that 6-sulfosialyl Lewis x in extended core 1 O-glycans, NeuNAcalpha2-->3Galbeta1-->4(Fucalpha1-->3(sulfo-->6))GlcNAcbeta1--> 3Galbeta1-->3GalNAcalpha1-->Ser/Thr, functions as an L-selectin ligand in high endothelial venules. Extended core 1 O-glycans can be synthesized when a core 1 extension enzyme is present. In this study, we first show that beta1,3-N-acetylglucosaminyltransferase-3 (beta3GlcNAcT-3) is almost exclusively responsible for core 1 extension among seven different beta3GlcNAcTs and thus acts on core 1 O-glycans attached to PSGL-1. We found that transcripts encoding beta3GlcNAcT-3 were expressed in human neutrophils and lymphocytes but that their levels were lower than those of transcripts encoding core 2 beta1,6-N-acetylglucosaminyltransferase I (Core2GlcNAcT-I). Neutrophils also expressed transcripts encoding fucosyltransferase VII (FucT-VII) and Core2GlcNAcT-I, whereas lymphocytes expressed only small amounts of transcripts encoding FucT-VII. To determine the roles of sialyl Lewis x in extended core 1 O-glycans, Chinese hamster ovary (CHO) cells were stably transfected to express PSGL-1, FucT-VII, and either beta3GlcNAcT-3 or Core2GlcNAcT-I. Glycan structural analyses disclosed that PSGL-1 expressed in these transfected cells carried comparable amounts of sialyl Lewis x in extended core 1 and core 2 branched O-glycans. In a rolling assay, CHO cells expressing sialyl Lewis x in extended core 1 O-glycans supported a significant degree of shear-dependent tethering and rolling of neutrophils and lymphocytes, although less than CHO cells expressing sialyl Lewis x in core 2 branched O-glycans. These results indicate that sialyl Lewis x in extended core 1 O-glycans can function as an L-selectin ligand and is potentially involved in neutrophil adhesion on neutrophils bound to activated endothelial cells.

The E-selectin S128R polymorphism is not a risk factor for coronary artery disease in patients with diabetes mellitus type 2

AIM/HYPOTHESIS

E-selectin is thought to play a key role in the early stages of vascular disease by facilitating the attachment of leukocytes to the endothelium. Recently, a polymorphism in the E-selectin gene (S128R) has been associated with higher E-selectin levels in patients with diabetes mellitus and with premature coronary artery disease. The impact of the S128R polymorphism on the development of diabetic coronary artery disease has not been investigated yet.

PATIENTS AND METHODS

A total of 254 patients recruited from the Division of Cardiology, University of Vienna with diabetes mellitus type 2 was assessed for the E-selectin S128R polymorphism by a novel mutagenic separated PCR, allowing fast and reliable genotyping without restriction enzyme digest. Ninety-five patients had a history of myocardial infarction, 90 were admitted with stable coronary artery disease whereas in 69 the presence of CAD could be excluded.

RESULTS

Of all 254 individuals tested, 197 (77.6%) exhibited wildtype E-selectin 128S genotype, 54 (21.3%) were heterozygous S128R and 3 (1.1%) were homozygous for the 128R allele. In all groups the genotype frequencies did not differ significantly. No associations were found between E-selectin genotype and coronary artery disease or myocardial infarction.

CONCLUSION/INTERPRETATION

In subjects suffering from diabetes mellitus type 2 the E-selectin S128R polymorphism is not associated with coronary artery disease nor with an increased risk for myocardial infarction. Thus, screening for this polymorphism is not indicated for risk assessment of CAD in patients with diabetes mellitus.

Polymorphonuclear leukocytes from individuals carrying the G329A mutation in the alpha 1,3-fucosyltransferase VII gene (FUT7) roll on E- and P-selectins

We recently identified several individuals carrying a missense mutation (G329A; Arg(110)-Gln) in the FUT7 gene encoding fucosyltransferase VII. This enzyme is involved in the biosynthesis of the sialyl Lewis x (Le(x)) epitope on human leukocytes, which has been identified as an important component of leukocyte ligands for E- and P-selectin. No enzyme activity was measurable in expression studies in COS-7 cells using the mutated FUT7 construct. One of the identified individuals carried this mutation homozygously. Flow cytometry analysis of polymorphonuclear leukocytes (PMN) from this individual showed a nearly complete absence of staining with mAbs directed against sialyl Le(x) and a diminished staining with an E-selectin IgG chimera. However, staining with P-selectin IgG chimera and Abs directed against P-selectin glycoprotein ligand-1 was not affected by the mutation. PMN from the homozygously mutated individual was further analyzed in an in vitro flow chamber assay. The number of rolling PMN and the rolling velocities on both E- and P-selectin were in the range of PMN from nonmutated individuals. FUT4 and FUT7 mRNA was quantified in PMN isolated from individuals carrying the FUT7 mutation. It was found that PMN from both FUT7 homozygously and heterozygously mutated individuals exhibited an elevated expression of FUT4 mRNA compared with PMN from FUT7 nonmutated individuals. The elevated expression of fucosyltransferase IV was reflected as an increased expression of the Le(x) and CD65s Ags on PMN from these individuals. The significance of the mutation was supported by transfection of BJAB cells.

Usefulness of CA19-9 versus CA125 for the diagnosis of endometriosis

OBJECTIVE

To investigate the clinical value of the serum CA19-9 level in comparison with the serum CA125 level for diagnosing and determining the severity of endometriosis.

DESIGN

Retrospective study.

SETTING

Department of Comprehensive Reproductive Medicine in a university hospital.

PATIENT(S)

One hundred one women with endometriosis and 22 without endometriosis participated in this study.

INTERVENTION(S)

Blood samples were collected before the operation (laparoscopy, oophrectomy, cystectomy, and/or hysterectomy), and tissue samples of ovarian chocolate cysts were collected during the operation.

MAIN OUTCOME MEASURE(S)

The serum CA19-9 and CA125 levels and the localization of these antigens in ovarian chocolate cysts.

RESULT(S)

The mean serum CA19-9 levels in patients at all stages of endometriosis were significantly higher than those in patients without endometriosis, and serum CA19-9 levels significantly correlated with the Revised American Fertility Society classification scores. Intense staining of CA19-9 was observed in 15 of the 20 samples of ovarian chocolate cysts.

CONCLUSION(S)

CA19-9 is a useful marker for determining the severity of endometriosis.

The expression of sialyl Lewis X in canine and feline mammary gland tumors

The expression of sialyl Lewis X (sLe(x)) in 93 canine and 15 feline mammary gland tumors (MGT) obtained by surgical resection at Veterinary Medical Center, the University of Tokyo was examined by immunohistochemistry. Their clinicopathological features and prognosis were also reviewed. Approximately 60% of MGT tissues showed sLe(x) positive expressions, while all normal mammary gland tissues were negative. However, its expression was not correlated with clinicopathological features and prognosis significantly. This study suggests that sLe(x) may be a tumor-associated antigen in canine and feline MGTs.

Glycosulfopeptides modeled on P-selectin glycoprotein ligand 1 inhibit P-selectin-dependent leukocyte rolling in vivo

Leukocytic inflammation can be limited by inhibiting selectin-dependent leukocyte rolling. In spite of intensive efforts to develop small molecule selectin inhibitors with defined structure-activity profiles, inhibition of P-selectin-dependent leukocyte rolling in vivo by such a compound has yet to be described. We recently reported that glycosulfopeptides (GSP), modeled on the high affinity selectin ligand PSGL-1, inhibit leukocyte binding to P-selectin in vitro. Here, we have used intravital microscopy to investigate whether GSP can inhibit P-selectin-dependent leukocyte rolling in vivo. Surgical preparation of the mouse cremaster muscle for intravital microscopy induced P-selectin-dependent leukocyte rolling. Baseline rolling was recorded for 1 min followed by i.v. injection of GSP. 2-GSP-6 and 4-GSP-6 substantially reversed P-selectin-dependent leukocyte rolling, whereas control GSP, which are not fully glycosylated, did not. Inhibition of leukocyte rolling by 2- and 4-GSP-6 lasted 2-4 min. Clearance studies with 125I-labeled 4-GSP-6 demonstrated rapid reduction in its circulating levels concurrent with accumulation in urine. These data represent the first demonstration that a precisely defined structure based on a natural P-selectin ligand can inhibit P-selectin-dependent leukocyte rolling in vivo.

Synthesis of a potent antagonist of E-selectin

A synthesis of an antagonist of E-selectin previously reported by a group at Novartis Pharma in Basel is described. An important feature involves the formation of an ether linkage based on a Rh(II)-catalyzed reaction. Stereocontrolled glycosylations rely on the anomeric activation of 2-pyridylthio carbonate as leaving group for the attachment of beta-D-galactopyranosyl and alpha-L-fucopyranosyl units on a common 1,5-anhydro D-glucitol scaffold.

Cell adhesion molecules, leukocyte trafficking, and strategies to reduce leukocyte infiltration

Leukocyte-endothelial cell interactions are mediated by various cell adhesion molecules. These interactions are important for leukocyte extravasation and trafficking in all domestic animal species. An initial slowing of leukocytes on the vascular endothelium is mediated by selectins. This event is followed by (1) activation of beta2 integrins after leukocyte exposure to cytokines and pro-inflammatory mediators, (2) adherence of leukocyte beta2 integrins to vascular endothelial ligands (eg, intercellular adhesion molecule-1 [ICAM-1]), (3) extravasation of leukocytes into tissues through tight junctions of endothelial cells mediated by platelet and endothelial cell adhesion molecule-1 (PECAM-1), and (4) perivascular migration through the extracellular matrix via beta1 integrins. Inhibiting excessive leukocyte egress and subsequent free radical-mediated damage caused by leukocyte components may attenuate or eliminate tissue damage. Several methods have been used to modify leukocyte infiltration in various animal models. These methods include nonspecific inhibition of pro-inflammatory mediators and adhesion molecules by nonsteroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids, inhibition of cytokines and cytokine receptors, and inhibition of specific types of cell adhesion molecules, with inhibitors such as peptides and antibodies to beta2 integrins, and inhibitors of selectins, ICAMs, and vascular cell adhesion molecule-1 (VCAM-1). By understanding the cellular and molecular events in leukocyte-endothelial cell interactions, therapeutic strategies are being developed in several animal models and diseases in domestic animal species. Such therapies may have clinical benefit in the future to overcome tissue damage induced by excessive leukocyte infiltration.

Immunohistochemical expression of CA19-9 and CA125 in mucoepidermoid and adenoid cystic carcinomas of the salivary gland

This study examined the immunohistochemical expression of carbohydrate antigens CA19-9 and CA125 and their relationship to various biological parameters in 27 mucoepidermoid carcinomas (MEC) and 18 adenoid cystic carcinomas (ACC) arising from salivary glands. The series showed higher immunopositivity for CA125 (67% for MEC; 33% for ACC) than for CA19-9 (59% for MEC; 11% for ACC). CA19-9 epitope was mainly expressed in cystic (MEC) and cribriform/tubular (ACC) components of carcinoma tissues. Solid components in MEC occasionally showed positive staining for CA19-9. CA125 was evenly expressed in both ACC and MEC tissues regardless of their different histological components. The positive expression of CA19-9 and CA125 in the carcinoma tissues did not influence the clinical course of patients with MEC and ACC. A significant relationship was only demonstrated between the immunohistochemical expression of CA125 and the low proliferative activity (LI) evaluated by Ki-67 immunohistochemistry. However, no significant relationship was found between LI and the patients' clinical course. These results suggest that the immunostaining for CA19-9 and CA125 provide no reliable data to predict the clinical course of patients with MEC and ACC of the salivary glands.

Macrosphelide B suppressed metastasis through inhibition of adhesion of sLe(x)/E-selectin molecules

Macrosphelide B (MSB), a 16-membered macrolide from Microsphaeropsis sp. FO-5050, inhibits adhesion of sialyl Lewis(x) (sLe(x))-expressing HL-60 cells to LPS-activated (E-selectin-expressing) human umbilical vein endothelial cells (HUVECs) in vitro. This study examines MSB effects on metastasis of B16/BL6 mouse melanoma cells (B16/BL6 cells) and L5178Y-ML mouse lymphoma cells in vivo and analyzes the MSB antimetastatic activity mechanism. When administered MSB at 20 mg/kg/day, lung metastatic nodules of B16/BL6 cells were significantly decreased (T/C = 45%). However, no inhibition of metastasis of L5178Y-ML cells to the spleen and liver was observed. Flow cytometry analysis showed that B16/BL6 cells expressed high levels of sLe(x) antigen, whereas expression on L5178Y-ML cells was low. Under in vitro conditions, B16/BL6 cells demonstrated a greater degree of adhesion to LPS-activated HUVECs than L5178Y-ML cells, but adhesion was significantly inhibited by MSB and sLe(x) antibody. Combined therapy of MSB and cisplatin (CDDP) induced remarkable lung metastasis inhibition without adverse effects of CDDP to the host. All these findings suggest that MSB suppresses lung metastasis of B16/BL6 cells by inhibiting cell adhesion to endothelial cells through the sLe(x) molecule.

Suppression of experimental lupus nephritis by aberrant expression of the soluble E-selectin gene

Circulating leukocytes, particularly neutrophils and monocytes, are important effector cells in the induction of many forms of glomerulonephritis. Adhesion molecules, especially selectins, are also thought to be critical for the development of this disease. We examined the possible suppressive effect of soluble E-selectin on the development of experimental lupus nephritis induced by the injection of a hybridoma clone (2B11.3) derived from an MRL/MpJ-lpr/lpr lupus mouse. This clone produces IgG3 antibodies that induce severe proliferative glomerulonephritis resembling lupus nephritis when injected into normal mice. Transgenic mice with a soluble E-selectin gene were injected intraperitoneally with the hybridoma cells and histopathologically examined on day 15. As a result, the development of glomerulonephritis was significantly suppressed. This suppression was characterized by fewer inflammatory cell infiltrates, compared with non-transgenic litter mates, despite the fact that there were no remarkable differences in immunoglobulin deposits or expression of E-selectin between the two groups. These findings suggest that by controlling inflammatory cell infiltration, soluble E-selectin plays a preventative role in the development of a particular type of lupus nephritis.

Cloning and sequencing of nineteen transcript isoforms of the human alpha2,3-sialyltransferase gene, ST3Gal III; its genomic organisation and expression in human tissues

The recruitment of human peripheral blood leukocytes (PBL) to sites of infection and inflammation requires the surface expression of Sialyl Lewis x glycoconjugates (SLe(x)) on white blood cells and their interaction with E- and P-selectins on activated endothelial cells. E-selectin has additionally been shown to interact with the sialyl Lewis a (SLe(a)) epitope. Human ST3Gal III codes for an alpha2,3-sialyltransferase involved in the biosynthesis of both SLe(a) and SLe(x) epitopes, although the latter with a lower efficiency. We have cloned and sequenced human ST3Gal III gene transcripts from human peripheral blood leukocytes, covering the coding region of this gene. Within our clones we isolated 19 different transcripts with a wide variety of deletions from 45 to 896 nucleotides, and insertions of 26 to 173 nucleotides. Among the insertions we identified two new exons (E3, E6). In order to map and characterise the ST3Gal III gene we used the GenBank database and "computer-cloned" and characterised the genomic organisation of the ST3Gal III gene. The coding sequences of the ST3Gal III gene stretch over a gene sequence of approximately 223 Kb comprised of 15 exons. RT-PCR and laser-induced fluorescent capillary electrophoresis (LIF-CE) were used to examine the expression of this gene in twenty-one human tissues, which showed a highly specific tissue expression pattern. Neural and muscular tissues showed the most complex patterns and were distinctly different from all other tissues examined.

ABO blood group antigens in oral mucosa. What is new?

Histo-blood group ABH (O) antigens are major alloantigens in humans. These antigens are widely distributed in human tissues and undergo changes in expression during cellular differentiation and malignant development. The ABH antigens have been characterized as terminal disaccharide determinants which represent secondary gene products. They are synthesized in a stepwise fashion from a precursor by the action of different glycosyltransferases. In non-keratinized oral mucosa, a sequential elongation of the carbohydrates is associated with differentiation of epithelial cells, resulting in expression of precursors on basal cells and A/B antigens on spinous cells. Reduction or complete deletion of A/B antigen expression in oral carcinomas has been reported, a phenotypic change that is correlated with invasive and metastatic potential of the tumours and with the mortality rates of the patients. Disappearance of the antigens is ascribed to the absence of A or B transferase gene expression. Several studies have shown that loss of A and B antigen expression is associated with increased cell motility, invasion in matrigel, and tumourigenecity in syngenic animals. In vivo studies of human oral wound healing show similarly decreased expression of A/B antigens on migrating epithelial cells. Some studies suggest that the relationship between expression of blood group antigens and cell motility can be explained by different degrees of glycosylation of integrins. Changes in ABO expression in tumours have, in some cases, been due to the A/B gene promoter, although little is known about the regulation of A, and B expression, in normal tissue.

Sialosyl-Le(x) expression defines invasive and metastatic properties of bladder carcinoma

BACKGROUND

Two types of transitional bladder carcinoma have been distinguished based on macroscopic morphology: type A papillary carcinomas, with papillomatous surface outgrowth without infiltration into muscular layer, and type B nodular carcinomas, with a nonpapillomatous surface appearance, most of which display infiltrative growth through muscular layer, and some of which display lymphatic or blood-borne metastasis. However, there is no specific predictor at early stages for later invasive and metastatic clinical outcome of patients with type B tumors.

METHODS

The study included 1) glycosphingolipid (GSL) composition of type A and B tumors; 2) histologic and immunohistologic patterns of nodular (type B) bladder carcinoma from 44 patients based on a special sampling procedure termed whole-layer core biopsy (WLCB) using the antisialosyl-Le(x) (anti-SLe(x); SLe(x): NeuAcalpha3Galbeta4[Fucalpha3]GlcNAcbeta3Galbeta4GlcCer) SNH3 antibody or other antibodies; 3) comparison of the incidence of metastasis in patients with SNH3 positive versus SNH3 negative primary tumors and of 5-year survival curves; 4) comparison of bladder carcinoma cell lines from tumors with high versus low malignancy in terms of expression patterns of SLe(x), SLe(a), and other carbohydrates, E-selectin dependent adhesion, and transcript levels of five fucosyltransferases.

RESULTS

Anti-SLe(x) monoclonal antibody (mAb) SNH3 staining of WLCB samples from 44 type B tumors showed that the majority of tumors (n = 31 patients) were SNH3 positive and the minority (n = 13 patients) were SNH3 negative. SNH3 positive patients had more lymph node or blood-borne metastasis and lower 5-year and 7-year survival rates, as indicated by Kaplan-Meier curves (P = 0.001). Staining of samples with other antibodies, including FH6 and CA19-9, was not correlated with long-term survival. Determination of GSL composition in extracts showed that SLe(x) ganglioside was present in all three patients with nodular tumors but absent in all three patients with papillary tumors tested. Bladder carcinoma cell lines from invasive tumors that maintained their metastatic properties were SNH3 positive, showed high levels of alpha1,3-fucosyltransferase VI (FT-VI) and FT-VII, and displayed E-selectin dependent adhesion. Cell lines from noninvasive tumors or normal bladder epithelia were negative for SNH3 reactivity, FT-VI, and FT-VII, and E-selectin dependent adhesion.

CONCLUSIONS

SLe(x) expression in primary bladder carcinoma, defined by the mAb SNH3, is a predictor of invasive and metastatic outcome. No other carbohydrate epitope examined to date has equal prognostic value.

Core 2 oligosaccharides mediate eosinophil and neutrophil peritoneal but not lung recruitment

We have investigated the importance of cell-surface serine- and/or threonine-linked oligosaccharide adhesion molecules synthesized by the Golgi enzyme core 2 beta-1,6-N-acetylglucosaminyltransferase (C2GlcNAcT) in mediating eosinophil trafficking to the lung in studies utilizing C2GlcNAcT-I-deficient mice. The number of bronchoalveolar eosinophils, the number of lung eosinophils, and airway responsiveness to methacholine were not significantly different in C2GlcNAcT-I-deficient compared with wild-type mice sensitized and challenged by inhalation with ovalbumin. C2GlcNAcT-I-deficient mice do not demonstrate defects in neutrophil trafficking to the lung in response to lipopolysaccharide (LPS). In contrast, ragweed-sensitized C2GlcNAcT-I-deficient mice exhibit significantly reduced eosinophil trafficking to the peritoneal cavity in response to ragweed peritoneal challenge. C2GlcNAcT-I-deficient mice also have significantly reduced neutrophil trafficking to the peritoneal cavity in response to LPS challenge. Overall, these studies demonstrate an important role for serine/threonine-linked oligosaccharides synthesized by the Golgi enzyme C2GlcNAcT-I in eosinophil and neutrophil trafficking to the peritoneum but not for eosinophil or neutrophil trafficking to the lung.

Adhesion molecules in human pancreatic cancer

BACKGROUND AND OBJECTIVES

Adhesion molecules are cell surface glycoproteins that are important in cell-to-cell and cell-to-extracellular matrix interactions. In the present study, we analyzed the adhesion molecules ICAM-1 (intercellular adhesion molecule-1), VCAM-1 (vascular cell adhesion molecule-1), and ELAM-1 (endothelial leukocyte adhesion molecule-1) in human pancreatic cancer.

METHODS

ICAM-1, VCAM-1, and ELAM-1 were analyzed in 20 pancreatic cancer specimens and 20 normal pancreatic tissues. mRNA expression encoding ICAM-, VCAM-1, and ELAM-1 was assessed with Northern blot analysis. The distribution and localization of ICAM-1, VCAM-1, and ELAM-1 was determined in the pancreatic specimens by immunohistochemistry.

RESULTS

Northern blot analysis revealed a 5.4-fold increase of ICAM-1 (P<0.01) and a 3.7-fold increase in VCAM-1 (P<0.01) mRNA expression in cancer samples in comparison with normal controls. In contrast, ELAM-1 mRNA levels did not show significant differences between the cancer and the normal tissues. Immunohistochemical analysis of cancer tissues showed strong immunostaining for ICAM-1 and VCAM-1, and faint immunostaining for ELAM-1 in the pancreatic cancer cells. Fibrotic or noncancerous pancreatic tissue adjacent to the cancer mass was devoid of any immunoreactivity for ICAM-1, ELAM-1, and VCAM-1. In contrast, the normal pancreas exhibited no immunoreactivity of ICAM-1, ELAM-1, and VCAM-1.

CONCLUSIONS

Enhanced expression of ICAM-1 and VCAM-1 in human pancreatic cancers suggests a role in tumor pathogenesis. The increase of these adhesion molecules might influence the detachment of cancer cells in the primary tumor, might contribute to cancer cell migration and the spread of cancer cells to distant organs, or both.

Increased expression of sialyl Lewis(x) antigen as a prognostic factor in patients with stage 0, I, and II gastric cancer

Immunohistochemically detected expression of sialyl Lewis(x) (Le(x)) antigen was analyzed in 101 stage 0-II gastric cancers to clarify its prognostic value after curative gastrectomy. Patients with a high-expression of sialyl Le(x) antigen within their tumors had shorter disease-specific intervals than those with negative- or low-expressing tumors (P<0.0001). This difference was noted particularly in stage I-B or II disease. Multivariate Cox's regression analysis revealed sialyl Le(x) antigen expression to be an independent predictor of disease-specific survival (Hazard ratio=9.10). In conclusion, the increased expression of sialyl Le(x) antigen may serve as a prognostic factor after curative surgery for stages 0-II gastric cancer.

Cimetidine increases survival of colorectal cancer patients with high levels of sialyl Lewis-X and sialyl Lewis-A epitope expression on tumour cells

Cimetidine has been shown to have beneficial effects in colorectal cancer patients. In this study, a total of 64 colorectal cancer patients who received curative operation were examined for the effects of cimetidine treatment on survival and recurrence. The cimetidine group was given 800 mg day(-1) of cimetidine orally together with 200 mg day(-1) of 5-fluorouracil, while the control group received 5-fluorouracil alone. The treatment was initiated 2 weeks after the operation and terminated after 1 year. Robust beneficial effects of cimetidine were noted: the 10-year survival rate of the cimetidine group was 84.6% whereas that of control group was 49.8% (P<0.0001). According to our previous observations that cimetidine blocked the expression of E-selectin on vascular endothelium and inhibited the adhesion of cancer cells to the endothelium, we have further stratified the patients according to the expression levels of sialyl Lewis antigens X (sL(x)) and A (sL(a)). We found that cimetidine treatment was particularly effective in patients whose tumour had higher sL(x) and sL(a) antigen levels. For example, the 10-year cumulative survival rate of the cimetidine group with higher CSLEX staining, recognizing sL(x), of tumours was 95.5%, whereas that of control group was 35.1% (P=0.0001). In contrast, in the group of patients with no or low levels CSLEX staining, cimetidine did not show significant beneficial effect (the 10-year survival rate of the cimetidine group was 70.0% and that of control group was 85.7% (P=n.s.)). These results clearly indicate that cimetidine treatment dramatically improved survival in colorectal cancer patients with tumour cells expressing high levels of sL(x) and sL(a).

Cimetidine in colorectal cancer--are the effects immunological or adhesion-mediated?

British Journal of Cancer (2002) 86, 159–160. DOI: 10.1038/sj/bjc/6600097www.bjcancer.com

© 2002 The Cancer Research Campaign

The glycosynapse

Physically distinguishable microdomains associated with various functional membrane proteins are one of the major current topics in cell biology. Glycosphingolipids present in such microdomains have been used as "markers;" however, the functional role of glycosyl epitopes in microdomains has received little attention. In this review, I have tried to summarize the evidence that glycosyl epitopes in microdomains mediate cell adhesion and signal transduction events that affect cellular phenotypes. Molecular assemblies that perform such functions are hereby termed "glycosynapse" in analogy to "immunological synapse," the membrane assembly of immunocyte adhesion and signaling. Three types of glycosynapses are so far distinguishable: (i) Glycosphingolipids organized with cytoplasmic signal transducers and proteolipid tetraspanin with or without growth factor receptors; (ii) transmembrane mucin-type glycoproteins with clustered O-linked glycoepitopes for cell adhesion and associated signal transducers at lipid domain; and (iii) N-glycosylated transmembrane adhesion receptors complexed with tetraspanin and gangliosides, as typically seen with the integrin-tetraspanin-ganglioside complex. The possibility is discussed that glycosynapses give rise to a high degree of diversity and complexity of phenotypes.

Therapeutic potential of a novel synthetic selectin blocker, OJ-R9188, in allergic dermatitis

1. We investigated the ability of a newly synthesized sugar derivative, OJ-R9188, [N-(2-tetradecylhexadecanoyl)-O-(L-alpha-fucofuranosyl)-D-seryl]-L-glutamic acid 1-methylamide 5-L-arginine salt, to block binding of selectins to their ligands in vitro and inhibit the infiltration of leukocytes in vivo. 2. OJ-R9188 prevented the binding of human E-, P- and L-selectin-IgG fusion proteins to immobilized sialyl Lewis(x) (sLe(x))-pentasaccharide glycolipid, with IC(50) values of 4.3, 1.3, and 1.2 microM, respectively. 3. In a mouse model of thioglycollate-induced peritonitis, OJ-R9188 at 10 mg kg(-1), i.v. inhibited neutrophil accumulation in the peritoneal cavity. In the IgE-mediated skin reaction, OJ-R9188 at 3 and 10 mg kg(-1), i.v. significantly inhibited extravasation of neutrophils and eosinophils into the inflammatory sites and at 10 mg kg(-1), i.v. also inhibited infiltration caused by picryl chloride-induced delayed-type hypersensitivity in mice. These results suggest that OJ-R9188 may be a useful selectin blocker, with activity against human and mouse E-, P- and L-selectins in vitro and in vivo, and that blocking selectin-sLe(x) binding is a promising strategy for the treatment of allergic skin diseases.

Carbohydrate mimetics-based glycosyltransferase inhibitors

The search for carbohydrate mimetics-based glycosyltransferase inhibitors is a dynamic field that emerged 10 years ago. This review presents a description of the different types of glycosyltransferase inhibitors containing a carbohydrate mimetic (primarily an iminosugar, a carbasugar or a C-glycoside) and data on their biological activity whenever such data are available. The purpose of this account is to foster a synergy between the two expanding research areas of glycomimetics and glycosyltransferases.

Sialosyl Le(a)-carrying gangliosides present on the surface of colon carcinoma cells are not directly involved in adhesion to E-selectin

We have shown previously that human colon cancer CX-1 cells contain lipid- and protein-bound sialosyl Lewis(a) structures that support the adhesion of these cells to E-selectin. Treatment of cancer cells with O-sialoglycoprotease did not decrease either the binding of anti-sialosyl Le(a) antibodies or binding to E-selectin-expressing CHO cells. This suggested that cleavage of sialomucins uncovered cryptic sialosyl Le(a) gangliosides that support such interactions. In the present study, inhibitors of glycolipid and O-glycan biosynthesis, d,l-threo-PPPP and GalNAc-alpha-O-benzyl, respectively, were used to study whether the binding of anti-sialosyl Le(a) antibody and adhesion of CX-1 cells to E-selectin can be mediated by sialosyl Le(a) gangliosides. Treatment of cancer cells with each of the inhibitors decreased the expression of the respective glycoconjugates as shown by TLC-binding assay and immunoblotting with anti-sialosyl Le(a) antibody. However, only slight differences in binding of antisialosyl Le(a) antibody to the surfaces of control and inhibitor-treated CX-1 cells were found by flow cytometry, as well no differences were observed in binding of control and inhibitor-treated CX-1 cells to E-selectin-expressing CHO cells, supporting the earlier hypothesis on the involvement of gangliosides in binding of anti-sialosyl Lewis(a) in the partial absence of mucin O-glycans. This hypothesis was further proven by electron microscopy data. Both native CX-1 and d,l-threo-PPPP-treated cells were labelled with anti-sialosyl Lewis(a) antibody mostly at a distance 70-90 nm from cell surface, suggesting interaction with protein-bound carbohydrate structures only. In contrast, the cancer cells treated with GalNAc-alpha-O-benzyl showed most of the staining around 20 nm distance from the plasmalemma, implying that the antibody interacts with lipid-bound sialosyl Lewis(a) instead. The electron microscopy data in conjunction with other results described in this report strongly support the hypothesis that sialosyl Lea gangliosides are not involved in the adhesion of CX-1 cells to E-selectin when mucins are present on the cell surface, but they may be involved in binding to E-selectin in their absence.

Linear synthesis of a protected H-type II pentasaccharide using glycosyl phosphate building blocks

A linear synthesis of a fully protected H-type II blood group determinant pentasaccharide utilizing glycosyl phosphate and glycosyl trichloroacetimidate building blocks is reported. Envisioning an automated solid-phase synthesis of blood group determinants, the utility of glycosyl phosphates in the stepwise construction of complex oligosaccharides, such as the H-type II antigen, is demonstrated. Installation of the central glucosamine building block required the screening of a variety of nitrogen protecting groups to ensure good glucosamine donor reactivity and protecting group compatibility. The challenge to differentiate C2 of the terminal galactose in the presence of other hydroxyl and amine protecting groups prompted us to introduce the 2-(azidomethyl)benzoyl group as a novel mode of protection for carbohydrate synthesis. The compatibility of this group with traditionally employed protecting groups was examined, as well as its use as a C2 stereodirecting group in glycosylations. The application of the 2-(azidomethyl)benzoyl group along with a systematic evaluation of glycosyl donors allowed for the completion of the pentasaccharide and provides a synthetic strategy that is expected to be generally amenable to the solid support synthesis of blood group determinants.

Alteration of integrins by interleukin-1alpha in human pancreatic cancer cells

INTRODUCTION

Adhesion of tumor cells to extracellular matrix (ECM) proteins plays an important role in tumor invasion and metastasis.

AIMS

To investigate the expression of integrins in human pancreatic cancer cell lines and its alteration by interleukin (IL)-1alpha to examine the mechanism of adhesion of metastatic human pancreatic cancer cells to ECM proteins.

METHODOLOGY

The expression of integrin subunits and their alteration by IL-1alpha were examined by flow-cytometric analysis and cellular enzyme-linked immunosorbent assay in three metastatic human pancreatic cancer cell lines (AsPC-1, BxPC-3, and SW1990) and two nonmetastatic cancer cell lines (PaCa-2 and PANC-1). In addition, assays of cancer cell adhesion to ECM proteins were performed to investigate if increased integrin expression actually affected the adhesive interaction between cancer cells and the putative integrin ECM ligands.

RESULTS

The alpha(6) subunit expressed in metastatic cancer cells was enhanced by IL-1alpha. Metastatic cancer cells also showed preferential adherence to laminin compared with nonmetastatic cancer cells, and this was enhanced by IL-1alpha.

CONCLUSION

In pancreatic cancer, the enhancement of alpha(6)beta(1) integrin by IL-1alpha through IL-1 receptor type I, as well as the expression of alpha(6)beta(1) integrin, plays an important role in metastasis formation.

Effect of trypsin-chymotrypsin (Chymoral Forte D.S.) preparation on the modulation of cytokine levels in burn patients

The present study was carried out in burn patients administered with Trypsin-Chymotrypsin (Chymoral Forte D.S.) preparation to observe if the acute-phase protein levels in the serum are modulated through the synthesis of IL-1beta and IL-6 and if the severity of the inflammatory phase could be regulated. The effects of Trypsin-Chymotrypsin preparation on the modulation of cytokine levels particularly, IL-6 and IL-1beta were analyzed in serum samples of 15 burn patients and compared with untreated controls. Significant differences in cytokine levels (P<0.05) were observed in untreated burn patients and Trypsin-Chymotrypsin preparation treated patients. There were significant variations in serum IL-6 and IL-1beta on the day of admission and post burn day 10 in treated as well as untreated burn patients. Patients with a higher percentage of total body surface area and sepsis showed a significant increase in IL-1beta and IL-6 in the serum. An increase in serum levels of both cytokines was observed on post burn day 1 and a significant decrease was observed in Trypsin-Chymotrypsin preparation treated patients on days 7 and 10. The possible role of the inflammatory cytokines in the pathophysiology of burns is discussed.

Synthesis of a set of di- and tri-sulfated galabioses

Among cell-adhesion molecules, L-selectin recognizes sulfated sLe(x) with relatively low affinity. Here, we aimed at artificial mimics by synthesizing a set of di- and tri-sulfated galabioses, which may surpass the affinity of sulfated sLe(x). As a strategy to obtain 3',6',6-tri-O-sulfogalabioses, regioselective reductive cleavage of 4,6- and 4',6'-di-O-benzylidenegalabioses was employed. Two suitably protected galactose precursors were conjugated to yield alpha and beta anomers (48 and 18%, respectively) by using a pentenyl galactoside donor and iodinium di-sym-collidine perchlorate as the catalyst. For synthesizing the 3',6-di-O-sulfogalabiose, however, a trichloroacetimidate donor was superior (52%) to the pentenyl one (30%).

Altered mRNA expression of sialyltransferase in squamous cell carcinomas of the cervix

OBJECTIVE

Increased sialylation has been reported in various kinds of cancers, but to date, sialylation of cervical carcinoma has never been evaluated. This study of the changes in messenger ribonucleic acid (mRNA) expression of the four sialyltransferases (ST3Gal I, ST3Gal III, ST3Gal IV, and ST6Gal I) in a normal cervix and that with FIGO stage IB1 squamous cell carcinoma was undertaken to assess the extent of sialylation associated with establishment of the carcinoma.

METHODS

Alterations in ST mRNA expression in FIGO IB1 cervical cancer (n = 30) and normal cervixes (n = 30) were examined by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

ST6Gal I expression was enhanced in squamous cell carcinoma of the cervix (P = 0.026, Mann-Whitney U test), but mRNA expression from the other three STs (ST3Gal I, ST3Gal III, and ST3Gal IV) was significantly down-expressed in squamous cell carcinoma of the cervix compared to the normal cervix (P = 0.003, P < 0.001, and P = 0.001, respectively). High ST6Gal I expression was associated with more invasive properties of cervical cancer, such as deep stromal invasion, lymph or vascular space involvement, and poor differentiation (P = 0.010, P < 0.001, P < 0.001, respectively).

CONCLUSIONS

A combination of enhanced ST6Gal I mRNA expression and decreased mRNA expression from ST3Gal I, ST3Gal III, and ST3Gal IV might be important in cervical cancer. Future studies will investigate whether RT-PCR detection of the expression of these enzymes can be helpful for prognostic purposes.

Role of cell surface glycosylation in mediating repair of human airway epithelial cell monolayers

Our laboratory recently demonstrated the pattern of cell surface glycosylation of nonsecretory central airway epithelium (Dorscheid DR, Conforti AE, Hamann KJ, Rabe KF, and White SR. Histochem J 31: 145-151, 1999), but the role of glycosylation in airway epithelial cell migration and repair is unknown. We examined the functional role of cell surface carbohydrates in wound repair after mechanical injury of 1HAEo(-) human airway epithelial and primary bronchial epithelial monolayers. Wound repair stimulated by epidermal growth factor was substantially attenuated by 10(-7) M tunicamycin (TM), an N-glycosylation inhibitor, but not by the inhibitors deoxymannojirimycin or castanospermine. Wound repair of 1HAEo(-) and primary airway epithelial cells was blocked completely by removal of cell surface terminal fucose residues by alpha-fucosidase. Cell adhesion to collagen matrix was prevented by TM but was only reduced ~20% from control values with prior alpha-fucosidase treatment. Cell migration in Blind Well chambers stimulated by epidermal growth factor was blocked by pretreatment with TM but alpha-fucosidase pretreatment produced no difference from control values. These data suggest that cell surface N-glycosylation has a functional role in airway epithelial cell adhesion and migration and that N-glycosylation with terminal fucosylation plays a role in the complex process of repair by coordination of certain cell-cell functions.

Identification of nine alternatively spliced alpha2,3-sialyltransferase, ST3Gal IV, transcripts and analysis of their expression by RT-PCR and laser-induced fluorescent capillary electrophoresis (LIF-CE) in twenty-one human tissues

In order to characterise the candidate alpha2,3-sialyltransferases necessary for biosynthesis of the selectin ligand SLe(x) and related antigens we have cloned and sequenced, from peripheral blood leukocytes of single individuals, various transcripts from the human ST3Gal III, IV and VI genes. Our clones have revealed a considerable heterogeneity in transcript isoforms. Among our ST3Gal IV clones we isolated nine alternatively spliced transcripts covering the coding region of the human ST3Gal IV gene (A1, A1 - 12, A1 + 18, A2, A2 - 12, A2 + 18, B, B - 12 and B + 18). Five of these isotranscripts A1 - 12, A1 + 18, A2 - 12, A2 + 18 and B + 18 have not been described before. In order to investigate if the alternatively spliced isotranscripts were specific for human PBL, we analysed the expression by RT-PCR and laser-induced fluorescent capillary electrophoresis (LIF-CE) in twenty other human tissues. We found a tissue specific expression of ST3Gal IV A1, A1 - 12, A1 + 18, A2, A2 - 12, A2 + 18 and B + 18 as well as a general expression of ST3Gal IV B and B - 12 isotranscripts in all tissues examined.

Comparative study for histology, proliferative activity, glycoproteins, and p53 protein between old and recent colorectal adenomas in Japan

The incidence of colorectal carcinoma is increasing in Japan. Malignant transformation in colorectal neoplasia is usually considered to be owing to adenoma-carcinoma sequence. Elucidation of the recent alteration in the biological properties of colorectal adenoma is sure to be useful to understand the recent increase of the colorectal carcinoma in Japan. We compared the histopathological feature, mitotic index, proliferative activity (Ki-67 labeling index), expression of glycoproteins such as MUC2 mucin, sialyl Lewis A (SLe(a)) and sialyl dimeric Lewis X (SLe(x)), and p53 protein overexpression, between 108 adenomas in the old period (Group A, from 1969 to 1985) and 140 adenomas in the recent period (Group B, from 1995 to 1998). The histological dysplasia, mitotic index and Ki-67 labeling index of the adenomas were significantly higher in Group B than in Group A. In contrast, the expression of MUC2 mucin, which is considered to be a differentiation factor of intestinal mucosal epithelium, was significantly reduced in Group B than in Group A. The SLe(a) and SLe(x) expressions showed no significant difference between them. The p53 expression showed no significant difference between them, except for the moderate dysplasia. These findings indicate that recent colorectal adenomas show more advanced degrees of histological dysplasia, more rapid growth, and reduced differentiation than colorectal adenomas, which developed at earlier times, and may be related with the recent high incidence of colorectal carcinoma in Japan.

Inhibition of fucosyltransferase V by a GDP-Azasugar

A GDP-azasugar conjugate was synthesized starting from an enzymatically obtained phosphorylated azasugar. It inhibits human fucosyltransferase V at micromolar concentrations, which is discussed in terms of transition state analogy.

Soluble E-selectin induces monocyte chemotaxis through Src family tyrosine kinases

Cellular adhesion molecules such as E-selectin function to recruit leukocytes into the inflammatory lesions of diseases such as rheumatoid arthritis (RA) and atherosclerosis. Monocytes are the key components of the cellular infiltrates present in these disorders. We hypothesized that soluble E-selectin (sE-selectin) might mediate the chemotaxis of monocytes. In this report, we show that sE-selectin induced normal human peripheral blood monocyte migration in the nanomolar range in a concentration-dependent manner. Neutralization studies using RA human joint synovial fluids and anti-E-selectin antibody showed a mean 31% reduction in RA synovial fluid-mediated monocyte chemotaxis (p < 0.05), indicating that sE-selectin is a major monocyte recruiter in RA. Next, we investigated the role of tyrosine phosphorylation pathways in sE-selectin-induced monocyte chemotaxis. Human peripheral blood monocytes stimulated with sE-selectin showed a time-dependent increase in the tyrosine phosphorylation of a broad range of cellular proteins, predominantly in the molecular size range of Src family kinases (50-60 kDa) and mitogen-activated protein kinases (MAPKs). Western blot analysis of Src family kinases showed a time-dependent increase in Src, Hck, and Lyn phosphorylation. The pretreatment of monocytes with the Src inhibitor AG1879: 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolol[3,4-d]pyrimidine (PP2) prior to stimulation with sE-selectin markedly inhibited Hck and Lyn phosphorylation, whereas the phosphorylation of Src was partially inhibited. In addition, the sE-selectin stimulation of monocytes resulted in the increased phosphorylation of extracellular signal-related kinase (ERK1/2) and p38 MAPK. The pretreatment of monocytes with PP2 showed 89 and 83% inhibition of ERK1/2 and p38 MAPK phosphorylation, respectively. sE-selectin also showed a time-dependent activation of Ras kinase. Furthermore, the pretreatment of monocytes with PP2 completely inhibited sE-selectin-mediated monocyte chemotaxis. Taken together, our data demonstrate a novel function for sE-selectin as a monocyte chemotactic agent and suggest that sE-selectin might be mediating its biological functions through the Src-MAPK pathway.

Design and synthesis of a new Sialyl Lewis X Mimetic: How selective are the selectin receptors?

The present paper reports the molecular modeling-based design and synthesis of an optically pure noncarbohydrate mimetic of sialyl Lewis X to inhibit E-selectin. Biological evaluation of the designed substance as well as that of its enantiomer gave, contrary to expectations, comparable IC50 values. Results are discussed in terms of receptor binding specificity and the molecular modeling protocol used.