Novel fucolipids accumulating in human adenocarcinoma. I. Glycolipids with di- or trifucosylated type 2 chain

Expression cloning and characterization of a novel murine alpha1, 3-fucosyltransferase, mFuc-TIX, that synthesizes the Lewis x (CD15) epitope in brain and kidney

The 3-fucosyl-N-acetyllactosamine (Lewis x, CD15, SSEA-1) carbohydrate epitope is widely distributed in many tissues and is developmentally expressed in some rodent and human tissues, i.e. brain and lung, and mouse early embryo. In such tissues, the Lewis x epitope is considered to be involved in cell-cell interactions. We isolated a novel mouse alpha1,3-fucosyltransferase gene, named mFuc-TIX, from an adult mouse brain cDNA library using the expression cloning method. On flow cytometric analysis, Namalwa cells transfected stably with the mFuc-TIX gene showed a marked increase in Lewis x epitopes but not sialyl Lewis x epitopes. As seen experiments involving oligosaccharides as acceptor substrates, mFuc-TIX transfers a fucose to lacto-N-neotetraose but not to either alpha2,3-sialyl lacto-N-neotetraose or lacto-N-tetraose. The substrate specificity of mFuc-TIX was similar to that of mouse myeloid-type alpha1,3-fucosyltransferase (mFuc-TIV). The deduced amino acid sequence of mFuc-TIX, consisting of 359 residues, indicated a type II membrane protein and shows low degrees of homology to the previously cloned alpha1,3-fucosyltransferases, i.e. mFuc-TIV (48.4%), mouse Fuc-TVII (39.1%), and human Fuc-TIII (43.0%), at the amino acid sequence level. A phylogenetic tree of the alpha1, 3-fucosyltransferases constructed by the neighbor-joining method showed that mFuc-TIX is quite distant from the other alpha1, 3-fucosyltransferases. Thus, mFuc-TIX does not belong to any subfamilies of known alpha1,3Fuc-Ts. The mFuc-TIX transcript was mainly detected in brain and kidney with the Northern blotting and competitive reverse transcription-polymerase chain reaction methods, whereas the mFuc-TIV transcript was not detected in brain with these methods. On in situ hybridization, the mFuc-TIX transcript was detected in neuronal cells but not in the glial cells including astrocytes. These results strongly indicated that mFuc-TIX participates in the Lewis x synthesis in neurons of the brain and may be developmentally regulated.

The alpha 1-->3 fucosylation at the penultimate GlcNAc catalyzed by fucosyltransferase VII is blocked by internally fucosylated residue in sialosyl long-chain poly-LacNAc: enzymatic basis for expression of physiological E-selectin epitope

Sialosyl-fucosyl poly-LacNAc without sialosyl-Lex epitope in myeloid cell line HL60 was shown to be the ligand for E-selectin-dependent adhesion, particularly under dynamic flow conditions, in our previous study (Handa K, Stroud MR, Hakomori S, Biochemistry 36, 12412-12420, 1997). HL60 cells express only fucosyl-transferase (FT) IV and VII. X3NeuAcVII3FucnLc10, a representative component showing E-selectin-dependent binding under dynamic flow conditions, is not alpha 1-->3 fucosylated at the penultimate GlcNAc catalyzed by FT-VII, but is alpha 1-->3 fucosylated at the internal GlcNAc catalyzed by FT-IV. VI3NeuAcnLc6 is converted to VI3NeuAcIII3FucnLc6 by FT-IV, but is also converted to VI3NeuAcV3FucnLc6 by FT-VII. Thus, penultimate fucosylation catalyzed by FT-VII is not restricted for nLc6 backbone, but is highly restricted for nLc10 backbone. The cooperative effect of FT-IV and FT-VII for synthesis of poly-LacNAc having sialosyl-Lex with internal fucosylation may be blocked or highly restricted in poly-LacNAc having more than two LacNAc units, because preferential alpha 1-->3 fucosylation by FT-IV takes place at internal GlcNAc, inhibiting penultimate fucosylation by FT-VII.

Lex glycosphingolipids-mediated cell aggregation

Glycoconjugates bearing oligosaccharide Lex, Galbeta1-->4(Fucalpha1-->3)GlcNAcbeta1-->3R, are found on the surface of several cell types. Although recent studies have indicated that Lexon both glycosphingolipids (GSL) and polylactosaminoglycans can mediate under certain experimental conditions Lex-Lexinteractions, cell-cell interactions based exclusively on LexGSLs have not been demonstrated. In this study we show that preincubation of nonaggregating rat basophilic leukemia (RBL) cells with purified LexGSLs resulted in incorporation of the GSLs into plasma membrane, as determined by immunostaining, and formation of aggregates in the presence of Ca2+; no aggregates were formed after preincubation of the cells with globoside or sphingomyelin. Lex-mediated aggregation was inhibited by removal of Ca2+or by addition of lactofucopentaose III but not by lactose or lacto-N-fucopentaose II. In a mixture of Lex-positive and Lex-negative RBL cells most of the aggregates were composed exclusively of Lex-positive cells. The combined data suggest that interactions between LexGSL on opposite cell surfaces are strong enough to allow formation of stable cell-cell contacts.

Fucose levels in sera and in tumours of colorectal adenocarcinoma patients

Fucose levels were determined in normal and tumour-derived tissues from patients with colorectal adenocarcinoma. Total, free and bound fucose were significantly higher (P < 0.001) in the tumoral tissue. Comparison of serum fucose levels between patients with colorectal cancer and control subjects indicated no statistically significant differences in total, free and bound fucose expressed as nmol/ml serum. However, when total and bound fucose were normalized to total protein (nmol/mg protein), an elevation in both parameters was found in colorectal cancer patients, although only that for total fucose was statistically significant (P < 0.001). A clear association between fucose content and clinical stage of patients according to the Dukes' classification can not be established, although patients at stage C showed higher levels of fucose both in serum and tissue. The current investigation provides direct evidence of a relationship between the elevation of fucose and the presence of tumour in colorectal cancer patients.

Identification of a cell surface protein with a role in stimulating human keratinocyte proliferation, expressed during development and carcinogenesis

In an attempt to define cell surface molecules with an important role in the development of squamous cell carcinomas (SCCs), we generated monoclonal antibodies (MoAbs) to a human keratinocyte cell line (FEP18-11-T1) capable of giving rise to SCCs in nude mice. MoAb 10G7 was selected for further study because it bound to a cell surface component preferentially expressed by this cell line as compared with normal human foreskin keratinocytes. This MoAb recognizes a cell surface protein (10G7 antigen) that is not detectable on normal keratinocytes in the foreskin in vivo, but whose expression is induced when the keratinocytes are dissociated from this tissue and placed in culture. Interestingly, the 10G7 antigen is downregulated upon keratinocyte differentiation in vitro. Consistent with its expression in hyper-proliferative epithelia in vitro, 10G7 antigen exhibited a classic oncofetal pattern of expression in vivo. Thus, although no reactivity was obtained with MoAb 10G7 in the epithelia of normal foreskin or cervical tissue, strong reactivity was detected in epithelia from genital lesions ranging from benign warts to invasive SCCs. Epidermis from developing fetal tissue also exhibited strong reactivity with MoAb 10G7. We have been able to demonstrate that this MoAb is capable of stimulating FEP18-11-T1 keratinocyte proliferation in vitro in a concentration-dependent manner in the absence of growth factors, suggesting that the 10G7 antigen may play an important role in regulating cellular proliferation during development and in carcinogenesis in epithelial tissues.

Glycosyl azides as building blocks in convergent syntheses of oligomeric lactosamine and Lewis(x) saccharides

Oligosaccharides containing type 2 lactosamine repeating units, e.g. neo-lacto-octaose and trimeric Lewis(x) derivatives, are constructed using neo-lactosamine azide building blocks. The azido group provides a favorable protection of the anomeric position which is stable to versatile protecting group manipulations and glycosylation reactions. On the other hand, glycosyl azides can be converted into glycosyl fluorides via a 1,3-dipolar cycloaddition with di-tert-butyl-acetylenedicarboxylate and subsequent treatment of the resulting N-glycosyl triazoles with hydrogen fluoride-pyridine complex. Activation of the lactosamine fluorides with Lewis acids affords the possibility to extend the oligosaccharide chain with disaccharide units. Suitable protecting group combinations within the galactose and the glucosamine portion of the lactosamine unit enable selective deprotection reactions and, subsequently, chain extension or branching, e.g. to yield Lewis(x) structures.

Oncofetal expression of blood group-related antigen on morules in thyroid carcinoma

Morule formation in association with characteristic biotinrich 'optically clear nuclei' were found in 7 of 2514 cases of thyroid carcinoma. The seven patients were all young females aged from 20 to 36 years who were suffering from either papillary carcinoma (six cases) or follicular carcinoma (one case). The ABH (O) blood group (BG) types were A in three, AB in two and H(O) in two patients. Immunohistochemical study revealed that ABH(O) and Lewis BG antigens were expressed more specifically on morules than on ordinary neoplastic cells of papillary or follicular carcinoma. Lewis BG antigens tested in the present study were as follows: CA50, CA19-9, stage-specific embryonic antigen 1 (SSEA-1), and sialyl SSEA-1. Ulex europaeus agglutinin I (UEA-I) histochemistry showed a positive reaction on all the morules of blood groups A and H(O) patients, but yielded completely negative results on the morules of type AB patients. Sequential digestion by neuraminidase and alpha-galactosidase unmasked the reactivity for UEA-I even on the morules of type AB patients. The consistent reactivity for UEA-I on the morules seemed to be related to specific expression of BG antigens, which were characterized as oncofetal expression. It is suggested that the morules in thyroid carcinoma might be a kind of fetal component induced by the differentiation of the neoplastic cells to the stage of immature embryonic cells.

Expression of the human cell surface glycoconjugates Lewis x and Lewis y by Helicobacter pylori isolates is related to cagA status

Monoclonal antibodies were used in an enzyme-linked immunosorbent assay for the detection of human Lewis immunodeterminants in the lipopolysaccharide of Helicobacter pylori. In 94 H. pylori isolates, expression of Lewis(x) (Le(x)) and Le(y) was a stable phenotypic marker independent of the growth medium and cell age; 46 (49%) of the isolates expressed both and 34 (36%) of the isolates expressed either Le(x) or Le(y); 14 (15%) were negative for both determinants. Twelve (13%) isolates expressed Le(b), 3 (3%) expressed Le(a), and 2 (2%) expressed sialyl-Le(x). H. pylori isolates positive for both Le(x) and Le(y) were predominantly cagA+ (P < 0.001) and possessed the s1 signal sequence (P < 0.05) and the m1 midregion type (P = 0.033) of vacA. Isogenic mutants of H. pylori CPY3401 were created by interruption of the cagA, picB, or ureA gene. The cagA-ablated strain (but not the picB- and ureA-ablated mutant strains) had significantly (P < 0.01) diminished expression of Le(y) compared with that of the wild-type strain; for all four strains, expression of Le(x) was similar. In conclusion, 89% of H. pylori isolates express Le determinants in their lipopolysaccharide, mimicking human cell surface glycoconjugates. Strong expression of Le(x) and Le(y) by cagA+ isolates could counterbalance their enhanced proinflammatory activities and thereby facilitate persistence.

F protein induced fusion of Sendai viral envelopes with mouse teratocarcinoma cells through Le(x)-Le(x) interaction

The efficiency of membrane fusion between reconstituted Sendai viral envelopes containing only the fusion protein (F-virosomes) and the plasma membrane of mouse teratocarcinoma cells (F9) in culture was assessed using an assay based on the relief of self-quenching of a lipid probe incorporated in the F-virosomes. The potential of F-virosomes was also evaluated for a targeted cytosolic delivery of lysozyme to F9 cells. [125I]Lysozyme entrapped into F-virosomes was taken to examine its fusion-mediated transfer to the F9 cells. Target specificity of the F-virosomes was confirmed by the interaction between the terminal Le(x) moiety (Gal beta 1-->4(Fuc alpha 1-->3)GlcNAc) of F protein and the Le(x) determinant on the membrane of F9 cells. Incubation of the loaded F-virosomes with cells led to fusion-mediated delivery, as inferred from the ability of cells to internalize lysozyme in the presence of azide (a potent inhibitor of endocytosis). These results suggest that carbohydrate-carbohydrate interaction is strong enough for target cell recognition followed by phospholipid bilayer melding induced by fusion glycoprotein of Sendai virus.

Prognostic significance of T antigen expression in patients with gastric carcinoma

BACKGROUND

Thomsen-Freidenreich (T) antigen, the immediate precursor antigen of the human blood MN system, has been detected in malignant cells, but not in most normal cells in which it is cryptic but can be unmasked by desialylation. In this study, we determined the prognostic significance of T antigen in specimens with gastric carcinoma.

METHODS

Expression of T antigen was studied immunohistochemically in 157 gastric carcinoma tissue specimens obtained at surgery from the First Department of Surgery, Osaka City University Medical School between 1983 and 1987.

RESULTS

T antigen expression was detected in 72 of the tumors (45.9%). The staining pattern was inclined to change from a luminal surface type to a cytoplasmic type in accordance with decreasing degree of cell differentiation. The rate of expression of T antigen significantly increased (P < 0.05) with serosal invasion, and was significantly higher (P < 0.01) in patients with hepatic or lymph node metastasis or peritoneal dissemination than in those without such metastasis or dissemination. Furthermore, among patients with Stage III or IV disease, those with T antigen-positive tumors had a significantly poorer prognosis than those with T antigen-negative tumors.

CONCLUSIONS

Our findings suggest that relationships exist between expression of T antigen and depth of invasion, hepatic metastasis, lymph node metastasis, or peritoneal dissemination, and that T antigen may be a good indicator of the prognosis of patients with gastric carcinoma.

Expression and localization of Lewis(x) glycolipids and GD1a ganglioside in human glioma cells

We analysed the glycolipid composition of glioma cells (N-370 FG cells), which are derived from a culture of transformed human fetal glial cells. The neutral and acidic glycolipid fractions were isolated by column chromatography on DEAE-Sephadex and analysed by high-performance thin-layer chromatography (HPTLC). The neutral glycolipid fraction contained 1.6 micrograms of lipid-bound glucose/galactose per mg protein and consisted of GlcCer (11.4% of total neutral glycolipids), GalCer (21.5%), LacCer (21.4%), Gb4 (21.1%), and three unknown neutral glycolipids (23%). These unknown glycolipids were characterized as Lewis(x) (fucosylneolactonorpentaosyl ceramide; Le(x)), difucosylneolactonorhexaosyl ceramide (dimeric Le(x)), and neolactonorhexaosyl ceramide (nLc6) by an HPTLC-overlay method for glycolipids using specific mouse anti-glycolipid antibodies against glycolipid and/or liquid-secondary ion (LSI) mass spectrometry. The ganglioside fraction contained 0.6 micrograms of lipid-bound sialic acid per mg protein with GD1a as the predominant ganglioside species (83% of the total gangliosides) and GM3, GM2, and GM1 as minor components. Trace amounts of sialyl-Le(x) and the complex type of sialyl-Le(x) derivatives were also present. Immunocytochemical studies revealed that GD1a and GalCer were primarily localized on the surface of cell bodies. Interestingly, Le(x) glycolipids and sialyl-Le(x) were localized not only on the cell bodies but also on short cell processes. Especially, sialyl-Le(x) glycolipid was located on the tip of fine cellular processes. The unique localization of the Le(x) glycolipids suggests that they may be involved in cellular differentiation and initiation of cellular growth in this cell line.

Origin of blood-group antigens: a self-declaration mechanism in somatic cell society

Blood-group antigens have been developed as a self-declaration mechanism in higher organisms, since blood cells carry different DNA from that of germ-line cells, and their selfishness must be strictly limited. If not, symbiosis between somatic DNA and germ-line DNA cannot be maintained since blood cells can express autonomy programmed within themselves. For the sake of maintenance of symbiosis, this self-declaration is not limited to blood cells and all somatic cells need a self-plural declaration mechanism such as blood-group antigens. Differentiation and development including induction and inhibition also depend on the self-declaration--recognition mechanism.

Chemical synthesis of a hexasaccharide comprising the Lewisx determinant linked beta-(1-->6) to a linear trimannosyl core and the precursor pentasaccharide lacking fucose

Phenyl 2,3,4-tri-O-acetyl-6-O-chloroacetyl-1-thio-alpha,beta-mannopyranoside (5) was condensed with benzyl O-(2,3,4-tri-O-benzyl-beta-D-mannopyranosyl)-(1-->6)-2,3,4-tri-O-benzyl- alpha-D- mannopyranoside (12) in the presence of NIS-triflic acid to give, after removal of the chloroacetyl group, the key intermediate, benzyl O-(2,3,4-tri-O-acetyl-alpha-D-mannopyranosyl)-(1-->6)-O-(2,3,4-tri-O-ben zyl- beta-D-mannopyranosyl)-(1-->6)-2,3,4-tri-O-benzyl-alpha-D-mannopyranosid e (14). A similar condensation of 6 and 7 with acceptor 14, followed by the removal of protecting groups, afforded 16 and 18, respectively. These compounds are expected to be useful in specificity studies of an antibody raised against a related, synthetic antigen that we are currently investigating.

Synthesis of precursors for the dimeric 3-O-SO3Na Lewis X and Lewis A structures

Stereoselective syntheses of 3-O-SO3Na-beta-Gal-(1-->4)-beta-GlcNAc- (1-->3)-beta-Gal-(1-->4)-GlcNAc-beta-OBn (15) and 3-O-SO3Na-beta-Gal-(1-->3)-beta-GlcNAc-(1-->3)-beta-Gal-(1-->3)- beta-GlcNAc-(1-->3)-beta-Gal-(1-->4)-Glc-beta-OBn (25) were accomplished through the use of two novel glycosyl donors, namely, ethyl O-(2,6-di-O-acetyl-3,4-O-isopropylidene-beta-D- galactopyranosyl)-(1-->4)-3-O-acetyl-2-deoxy-2-phthalimido-1-thio-6-O- trimethylacetyl-beta-D-glucopyranoside (8). and ethyl O-(2,6-di-O-acetyl-3,4-O-isopropylidene-beta-D-galactopyranosyl)- (1-->3)-4-O-acetyl-2-deoxy-2-phthalimido-1-thio-6-O-trimethylace tyl-beta-D-glucopyranoside (18).

Expression of sulfomucins in normal mucosae, colorectal adenocarcinomas, and metastases

We have examined the expression of specific mucin antigens in tissue sections from 92 cases of colorectal carcinoma, using sulfomucin-specific monoclonal antibody (MAb) 91.9H. The expression of sulfomucins was high in normal mucosae and much lower in primary colorectal carcinoma, in metastatic lesions in lymph nodes or in liver. The intracellular localization of sulfomucins was also different among these tissues. In normal mucosae, MAb 91.9H binding was seen in the supranuclear area, presumably Golgi complexes, the luminal surface, and secretory products. In primary colorectal carcinomas and in their metastatic lesions, MAb 91.9H was preferentially localized in the cell surface and substances attached to the luminal surface of glandular structures. Analysis of the lysates of normal and tumor tissues showed that very-high-molecular-weight components contained the antigenic epitopes. The intensity of MAb 91.9H binding was lower in tumors at advanced stages than in tumors at early stages. These high-molecular-weight components were apparently reactive with MAb FH6 specific for sialyl-Le(X) (s-Le(X) structures. Histological specimens with low levels of MAb 91.9H reactivity often exhibited relatively high levels of MAb FH6 reactivity. These two mucins may have reversed expression during carcinogenesis and carcinoma progression, and this change may be related to metastatic potential.

Synthesis of the saccharide moiety of galactosylgloboside (SSEA-3) and its conjugation to bovine serum albumin and Sepharose

The pentasaccharide glycoside corresponding to galactosylgloboside (SSEA-3), beta-D-Gal p-(1-->3)-beta-D-Gal pNAc-(1-->3)-alpha-D-Gal p-(1-->4)-beta-D-Gal p-(1-->4)-beta-D-Glc p-1-OCH2CH2Si-(CH3)3 (4), was synthesized via glycosylation (87%) of 2-(trimethylsilyl)ethyl 2,3,6-tri-O-benzyl-4-O-[2,3,6-tri-O-benzyl-4-O-(2,4, 6-tri-O-benzyl-alpha-D-galactopyranosyl)-beta-D-galactopyranosyl]-beta-D - glucopyranoside (2) with the glycosyl donor methyl 4,6-di-O-acetyl-2-deoxy-2-phthalimido-3-O-(2,3,4, 6-tetra-O-acetyl-beta-D-galactopyranosyl)-1-thio-beta-D-galactopyranosid e (1), followed by removal of protecting groups. Compound 4 was transformed into the spacer glycoside beta-D-Gal p(1-->3)-beta-D-Gal pNAc-(1-->3)-alpha-D-Gal p-(1-->4)-beta-D-Gal p-(1-->4)-beta-D-Glc p-1-SCH2CH2COOH (10), which was coupled to bovine serum albumin (BSA), and Sepharose beads, to give the corresponding neoglycoprotein (11, 6 mol of saccharide/mol of BSA), and glycosylated Sepharose (12, 2.7 mumol of saccharide/mL of sedimented beads), respectively. An improved synthesis of a protected globotetraoside beta-D-Gal pNAc-(1-->3)-alpha-D-Gal p-(1-->4)-beta-D-Gal p-(1-->4)-beta-D-Glc p-1-OCH2CH2SiMe3 is also reported.

Acceptor specificity of different length constructs of human recombinant alpha 1,3/4-fucosyltransferases. Replacement of the stem region and the transmembrane domain of fucosyltransferase V by protein A results in an enzyme with GDP-fucose hydrolyzing activity

The acceptor specificity of recombinant full-length, membrane-bound fucosyltransferases, expressed in COS-7 cells, and soluble, protein-A chimeric forms of alpha 1,3-fucosyltransferase (Fuc-T) III, Fuc-TIV, and Fuc-TV was analyzed toward a broad panel of oligosaccharide, glycolipid, and glycoprotein substrates. Our results on the full-length enzymes confirm and extend previous studies. However, chimeric Fuc-Ts showed increased activity toward glycoproteins, whereas chimeric Fuc-TIII and Fuc-TV had a decreased activity with glycosphingolipids, compared to the full-length enzymes. Unexpectedly, chimeric Fuc-TV exhibited a GDP-fucose hydrolyzing activity. In substrates with multiple acceptor sites, the preferred site of fucosylation was identified. Fuc-TIII and Fuc-TV catalyzed fucose transfer exclusively to OH-3 of glucose in lacto-N-neotetraose and lacto-N-tetraose, respectively, as was demonstrated by 1H NMR spectroscopy. Thin layer chromatography immunostaining revealed that FucT-IV preferred the distal GlcNAc residue in nLc6Cer, whereas Fuc-TV preferred the proximal Gl-cNAc residue. Incubation of Fuc-TIV or Fuc-TV with VI3NeuAcnLc6Cer resulted in products with the sialyl-LewisX epitope as well as the VIM-2 structure. To identify polar groups on acceptors that function in enzyme binding, deoxygenated substrate analogs were tested as acceptors. All three Fuc-Ts had an absolute requirement for a hydroxyl at C-6 of galactose in addition to the accepting hydroxyl at C-3 or C-4 of GlcNAc.

Possible involvement of tumour cell membrane gangliosides in platelet-tumour cell interactions

The possible correlation(s) between platelet proaggregating activity, and sialic acid content and ganglioside expression of six human colorectal tumour cell lines (CBS, GEO, HT-29, WiDr, MIP and DLD-1) was evaluated. The three cell lines (HT-29, WiDr and DLD-1) capable of inducing remarkable in vitro platelet aggregation, had significantly higher amounts of lipid-bound sialic acid than those cell lines characterised by a lower platelet proaggregating activity (GEO, CBS and MIP). High performance thin-layer chromatography demonstrated the presence of one band comigrating with GM3 in all cell lines, while GD1a and GT1b comigrating gangliosides were present only in HT-29, WiDr and DLD-1 cells. Finally, an increased platelet pro-aggregating activity of GEO and CBS cell lines was observed after the incorporation of exogenous gangliosides. The present data support the hypothesis that lipid-bound sialic acid may be involved in platelet-tumour cell interactions.

The immunologically reactive O-linked polysaccharide chains derived from circulating cathodic antigen isolated from the human blood fluke Schistosoma mansoni have Lewis x as repeating unit

The gut-associated excretory antigen circulating cathodic antigen (CCA) was isolated by immunoaffinity chromatography from adult Schistosoma mansoni worms, which were collected from infected golden hamsters. This antigen is probably involved in protection of the schistosome gut and is increasingly used in highly sensitive and specific immunodiagnostic assays. Amino acid analysis before and after alkaline borohydride treatment of CCA and monosaccharide analysis indicated that CCA is O-glycosylated mostly via GalNAc-Thr. After reductive alkaline treatment, the O-linked carbohydrate chains were fractionated by gel-permeation chromatography, followed by normal-phase HPLC on LiChrosorb-NH2. Carbohydrate-positive fractions were investigated by one-dimensional and two-dimensional 1H-NMR spectroscopy, fast atom bombardment mass spectrometry and collision-induced-dissociation tandem mass spectrometry. The analyses showed that the low-molecular-mass O-linked oligosaccharide alditols (the minor fraction) consist of disaccharides to hexasaccharides having the Gal beta (1-3)GalNAc-OL core in common. The major carbohydrate fraction comprises a population of polysaccharides, containing Lewis x repeating units (-3)Gal beta (1-4)[Fuc alpha (1-3)]GlcNAc beta (1-). CCA-specific monoclonal antibodies and IgM antibodies in patient sera recognized the fucosylated O-linked carbohydrate antigenic structures. Since CCA evokes a strong IgM antibody response and carbohydrate structures containing repeating Lewis x units are found on circulating neutrophils, it is proposed that the antigenic poly-Lewis x polysaccharide of CCA is involved in the induction of auto-immunity against granulocytes, resulting in the mild to moderate neutropenia observed during schistosome infection.

An immunohistochemical employer monoclonal antibodies against Le(a), sialyl Le(a), Le(x), and sialyl Le(x) antigens in primary colorectal, carcinomas and lymph node and hepatic lesions

The immunohistochemical expression of sialylated and non-sialylated forms of both Le(x) and Le(a) were studied in 87 carcinomas and 42 normal mucosal specimens of colon and rectum, as well as in 32 metastatic lymph nodes and 9 hepatic lesions, using an indirect immunoperoxidase staining. Their antigens were expressed in normal mucosa with the following frequencies: Le(a), 95.2% (40/42); sialyl Le(a), 88.1% (37/42); Le(x), 95.2% (40/42); and sialyl Le(x), 17.0% (7/42), whereas in carcinomas, the respective rate of frequency were: 78.2% (68/87); 78.2% (68/87); 90.8% (79/87); and 93.1% (81/87). Sialyl Le(x) antigen showed the highest tumor specificity compared to other antigens. In three normal mucosal specimens and four carcinomas with Le(a-b-) phenotype, the expression of type 1 antigens (Le(a) and sialyl Le(a)) was not consistent, whereas type 2 antigens (Le(x) and sialyl Le(x)) were consistently observed in carcinomas. The staining of type 1 antigens and Le(x) was decreased in metastatic lesions compared with primary carcinomas, whereas sialyl Le(x) antigen had the same positive-staining rate in both. Metastatic carcinoma expressed the sialylated form more predominantly than the non-sialylated form in type 2 antigens whereas the opposite result was observed in type 1 antigens. These results suggested that: (a) sialyl Le(x), defined by monoclonal antibody CSLEX1, may be useful as a tumor-associated antigen in colorectal carcinoma, and (b) the alteration of Lewis-related carbohydrate antigens in cancer cell membranes, including sialylation and/or aberrant glycosylation, may be related to metastatic behavior.

Assessment of human colorectal biopsies by 1H MRS: correlation with histopathology

Samples (3 mm3) of histopathologically normal (n = 15) and carcinomatous tissue (n = 15) were obtained from colectomy specimens and examined by 1H MRS. A combination of one- and two-dimensional spectra, obtained with appropriate acquisition and processing parameters, provide multiple diagnostic parameters allowing the distinction between normal and carcinomatous tissue. The diagnostic parameters include resonances from choline, choline-based, and other metabolites, cell surface fucosylation, and altered lipid profiles. Tissues histopathologically classified as normal, while remaining distinct from the malignant spectral profile, were found to fit into two categories, one of which had some of the spectral characteristics of malignancy. These results indicate that 1H MRS identifies abnormal colorectal mucosa, which is not morphologically manifest. Such abnormalities have been reported previously to exist in premalignant colorectal tissue by monoclonal antibody studies. Collectively, these results suggest that a clinical study of colorectal biopsies by 1H MRS could provide support for the use of MRS as an adjunct to current pathological procedures.

The use of human milk fucosyltransferase in the synthesis of tumor-associated trimeric X determinants

We have studied the fucosylation of a chemically synthesized trimer of N-acetyllactosamine [(LacNAc)3-EtPhNHCOCF3] with a fucosyltransferase preparation from normal human milk, which utilizes both type-1 and type-2 structures, whether sialylated or not. When fucose residues were added enzymically to the (LacNAc)3-EtPhNHCOCF3 hexasaccharide, mono-, di-, or trifucosylated oligosaccharide species were formed, containing the Lewisx determinant (Gal beta 1-->4[Fuc alpha 1-->3]Glc-NAc beta 1-->3). With excess GDP-fucose and prolonged reaction times, the trifucosylated product was formed in almost quantitative yield. Kinetic analysis of the fucosylation reaction indicated that there is a significant difference in the rate of transfer of the first, second and third fucose residues onto the acceptor molecule. The location of the fucose residues in the monofucosylated and difucosylated intermediate products was assessed by analyzing the digests obtained after endo-beta-galactosidase treatment by HPLC and reverse-phase chromatography. In addition, the fucosylated (LacNAc)3-EtPhNHCOCF3 structures were characterized by HPLC and were identified by 400-MHz 1H-NMR spectroscopy. There is a highly preferred order in which the fucosyl residues are attached to (LacN-Ac)3-EtPhNHCOCF3. In the major pathway, the first two fucose residues are transferred with equal preference to the medial (GN3) and proximal (GN1) GlcNAc residues, whereas the third fucose is attached to the distal (GN5) GlcNAc residue. These results are of relevance in understanding the role of alpha-3-fucosyltransferase in the biosynthesis of Lewisx-related cell-surface carbohydrate structures, that function as ligands for selectin-type cell-adhesion molecules and may play a role in the invasion and metastasis of several carcinoma.

Expression of Lewis X-related antigens in adenocarcinomas of lung

Fifty primary lung adenocarcinomas were examined immunohistochemically using monoclonal antibodies to determine changes in the expression of N-acetyl-lactosamine (blood group type-2 chain), LeX, LeY and sialyl LeX-i. These antigens were expressed in 60%, 70%, 90% and 94% of carcinomas, respectively; in 8%, 12%, 56% and 86% of normal broncho-bronchiolar epithelium; and in 32%, 0%, 100% and 0% of normal alveolar epithelium. The greater the complexity of the antigenic structure, the greater the incidence of positive staining in the adenocarcinomas. Although the more complex antigens such as sialyl LeX-i and LeY have also been demonstrated in the sera of lung cancer patients, they were not always cancer-selective in our immunohistochemical study. In contrast, the less complex antigens such as N-acetyl-lactosamine (type-2 chain) and LeX seem to be cancer-selective, as they showed low positivity in normal lung tissue.

Clinical aspects of glycoprotein biosynthesis

Glycoproteins are widely distributed among species in soluble and membrane-bound forms, associated with many different functions. The heterogenous sugar moieties of glycoproteins are assembled in the endoplasmic reticulum and in the Golgi and are implicated in many roles that require further elucidation. Glycoprotein-bound oligosaccharides show significant changes in their structures and relative occurrences during growth, development, and differentiation. Diverse alterations of these carbohydrate chains occur in diseases such as cancer, metastasis, leukemia, inflammatory, and other diseases. Structural alterations may correlate with activities of glycosyltransferases that assemble glycans, but often the biochemical origin of these changes remains unclear. This suggests a multitude of biosynthetic control mechanisms that are functional in vivo but have not yet been unraveled by in vitro studies. The multitude of carbohydrate alterations observed in disease states may not be the primary cause but may reflect the growth and biochemical activity of the affected cell. However, knowledge of the control mechanisms in the biosynthesis of glycoprotein glycans may be helpful in understanding, diagnosing, and treating disease.

Lex and related structures as adhesion molecules

Le(x) (alpha 1-->3 fucosylated type 2 chain) functions as an adhesion molecule capable of Ca(2+)-mediated homotypic binding. Cells with high surface expression of Le(x) therefore exhibit strong self-aggregation (based on Le(x)-Le(x) interaction) in the presence of Ca2+. In this review, I have summarized several lines of supporting data for this concept, and the role of Le(x)-Le(x) interaction in the process of embryo compaction and autoaggregation of F9 teratocarcinoma cells. In general, cell adhesion events based on Le(x)-Le(x) interaction may be followed and reinforced by integrin- or Ig receptor-based adhesion systems. SLe(x), the 2-->3 sialosyl derivative of Le(x), and its positional isomer SLe(a), have been identified as the target molecules for selectin-dependent cell adhesion. Adhesion of leukocytes or tumour cells to ECs or platelets, which express E-selectin and P-selectin respectively, is initiated by this process. The target epitopes SLe(x) and SLe(a) are presented mainly on transmembrane glycoproteins having many clusters of O-linked carbohydrate chains. Therefore, inhibition of O-glycosylation may be effective for blocking selectin-mediated cell adhesion. The abundant presence of Le(x) epitope in the central nervous system, and the physiological changes of Le(x) expression as described in this monograph, reflect the adhesive properties of this molecule and its sialyosylated and/or fucosylated derivatives.

The blood group antigen-related glycoepitopes: key structural determinants in immunogenesis and AIDS pathogenesis

This overview will focus on the functional and pathophysiological aspects of blood group antigen (BGA)-related glycodeterminants with regard to immunogenesis and AIDS pathogenesis. It has been postulated that in a broad range of histogenetically different tissues and organs, BGA-related glycoepitopes are expressed on the cell surface at definite stages of cell differentiation. These glycoepitopes are expressed during embryogenesis, organogenesis, tissue repair, regeneration, remodelling and maturation when 'sorting-out' of one homotypic cell population from a heterotypic assemblage of cells occurs (1). In this event, the BGA-related glycoepitopes, if being expressed on the cell surface, play roles of key structural determinants in cell-cell recognition, association and aggregation. This mechanism will be discussed in relation to immunogenesis with regard to antigen presentation, self-non-self discrimination, and positive and negative selection during thymic education. It is postulated that the appearance of BGA-related glycoepitopes on the cell membrane is a consequence of the association of major histocompatibility complex antigens (MHC) and peptides, with the subsequent elimination of cells carrying a high density of BGA-related glycoepitopes on their surface. After human immunodeficiency virus (HIV) glycoproteins are glycosylated by host cell glycosyltransferases, the virus may use the BGA-related glycodeterminants as ligands and/or receptors for expansion to a spectrum of target cells during AIDS development and generalization of the infection throughout the body. We will review the experimental evidence that supports the concept that HIV uses an alternative to the gp120/CD4 ligand/receptor system, and that the alternative mechanism is probably carbohydrate-mediated in nature.

Occurrence and specificities of α3-fucosyltransferases

The Le(x) (CD15) carbohydrate antigen and sialylated and oligomeric derivatives thereof have been implicated in cell adhesion processes. Expression of these antigens is developmentally regulated and (re)occurrence of several members of this group has been reported in malignant transformation of cells. Studies on the enzymology and genetics of alpha 3-fucosyltransferases, glycosyltransferases that play a key role in the biosynthesis of these antigens, would yield insight in the regulation of expression of these carbohydrate structures. In this paper the existing literature on these enzymes is reviewed and placed in the context of cell adhesion and malignancy.

A facile synthesis of nitrophenyl oligosaccharides containing the O-alpha-L-fucopyranosyl-(1----3)-2-acetamido-2-deoxy-beta-D-glucopyrano syl unit at their nonreducing end

A facile approach towards the synthesis of 4-nitrophenyl O-alpha-L-fucopyranosyl-(1----3)-2-acetamido-2-deoxy-beta-D-glucopyra nos ide, 2-nitrophenyl O-alpha-L-fucopyranosyl-(1----3)-O-(2-acetamido-2-deoxy-beta-D-glucop yra nosyl)- (1----6)-2-acetamido-2-deoxy-alpha-D-galactopyranoside, 4-nitrophenyl O-alpha-L-fucopyranosyl-(1----3)-O-(2-acetamido-2-deoxy-beta-D-glucop yra nosyl)- (1----6)-alpha-D-mannopyranoside, and 4-nitrophenyl O-alpha-L-fucopyranosyl-(1----3)-O-(2-acetamido-2-deoxy-beta-D-glucop yra nosyl)-(1----6)-beta-D-galactopyranoside has been accomplished through the development and use of methyl 3,4-O-isopropylidene-2-O-(4-methoxybenzyl)-1-thio-beta-L-fucopyranoside as the glycosyl donor.

Primary structure of four human milk octa-, nona-, and undeca-saccharides established by 1H- and 13C-nuclear magnetic resonance spectroscopy

The structures of two octasaccharides, one nonasaccharide, and one undecasaccharide, isolated from human milk, have been investigated by 1H- and 13C-nuclear magnetic resonance spectroscopy. The structures of these oligosaccharides are: beta-D-Galp-(1----4)-[alpha-L-Fucp- (1----3)]-beta-D-GlcpNAc-(1----3)-beta-D-Galp-(1----4)-[alpha-L-Fucp+ ++- (1----3)]-beta-D-GlcpNAc-(1----3)-beta-D-Galp-(1----4)-D-Glc; beta-D-GALp-(1----3)-[alpha-L-Fucp-(1----4)]-beta-D-GlcpNAc-(1---- 3)-beta-D - Galp-(1----4)-[alpha-L-Fucp-(1----3)]-beta-D-GlcpNAc-(1----3)-beta -D-Galp- (1----4)-D-Glc; beta-D-Galp-(1----4)-[alpha-L-Fucp-(1----3)]-beta-D-GlcpNAc-(1---- 6)-(alpha - L-Fucp-(1----2)-beta-D-Gal-(1----3)-[alpha-L-Fucp-(1----4)]- beta-D-GlcpNAc- (1----3))-beta-D-Galp-(1----4)-D-Glc; and alpha-L-Fucp-(1----2)-beta-D-Galp-(1----3)-beta-D-GlcpNAc-(1----3) -beta-D- Galp-(1----4)-[alpha-L-Fucp-(1----3)]-beta-D-GlcpNAc-(1----6)-[alp ha-L- Fucp-(1----2)-beta-D-Galp-(1----3)-beta-D-GlcpNAc-(1----3)]-beta-D -Galp- (1----4)-D-Glc. The two octasaccharides have been previously isolated from human milk as a mixture, and in a pure form from new-born feces, but the n.m.r. data were not provided. These two octasaccharides display the di-Lewis X and the composite Lewis A-Lewis X antigenic determinant, previously described as neo-antigens of adenocarcinoma cell lines.

The blood group antigens (BGA)-related glycoepitopes. A key structural determinant in immunogenesis and cancer pathogenesis

This overview has been focused on the functional and pathophysiological aspects of blood group antigens (BGA)-related glycodeterminants. It has been postulated that in a broad range of histogenetically different tissues and organs BGA-related glycoepitopes are expressed on the cell surface at definite stages of cell differentiation during embryogenesis, organogenesis, tissue repair, regeneration, remodeling and maturation when 'sorting-out' behaviour of one homotypic cell population from heterotypic assemblage of cells occurs. In this event the BGA-related glycoepitopes, if being expressed on the cell surface, play a role of key structural determinants in cell-cell recognition, association and aggregation. This mechanisms has been discussed in relation to immunogenesis regarding of antigen presentation, self-non-self discrimination, positive and negative selection during thymic education. It is postulated that the appearance of the BGA-related glycoepitopes on the cell membrane is a consequence of the association of MHC and peptides, with subsequent elimination of cells carring high density of BGA-related glycoepitopes on their surface. In cancer it has been considered as a key mechanism of phenotypic divergence of tumor cells, immunoselection, tumor progression and metastasis.