Use of N-acetyl-2'-O-methyllactosamine as a specific acceptor for the determination of alpha-L-(1----3)-fucosyltransferase in human serum

Fucosylated Glycans in α1-Acid Glycoprotein for Monitoring Treatment Outcomes and Prognosis of Cancer Patients

One standard treatment option for advanced-stage cancer is surgical resection of malignant tumors following by adjuvant chemotherapy and chemoradiotherapy. Additionally, neoadjuvant chemotherapy may be applied if required. During the time course of treatments, patients are generally followed by computed tomography (CT) surveillance, and by tumor marker diagnosis. However, currently, early evidence of recurrence and/or metastasis of tumors with a clinically relevant biomarker remains a major therapeutic challenge. In particular, there has been no validated biomarker for predicting treatment outcomes in therapeutic settings. Recently, we have looked at glycoforms of serum α₁-acid glycoprotein (AGP) by using a crossed affinoimmunoelectrophoresis with two lectins and an anti-AGP antibody. The primary glycan structures of AGP were also analyzed by a mass spectrometer and a novel software in a large number of patients with various cancers. Accordingly, the relative abundance of α1,3fucosylated glycans in AGP (FUCAGP) was found to be significantly high in cancer patients as compared with the healthy controls. Further, strikingly elevated levels of FUCAGP were found in patients with poor prognosis but not in patients with good prognosis. In the current study, levels of FUCAGP in serum samples from various cancer patients were analyzed and 17 patients including 13 who had undergone chemotherapy were followed for several years post operation. FUCAGP level determined diligently by using a mass spectrometer was found to change along with disease prognosis as well as with responses to treatments, in particular, to various chemotherapies. Therefore, FUCAGP levels measured during following-up of the patients after operation appeared to be clinically relevant biomarker of treatment intervention.

Tumor cells as the origin of elevated serum alpha1,3fucosyltransferase in association with malignancy

We have previously reported that the elevated activities of serum alpha 1,3fucosyltransferase reverted to normal levels after curative removal of the tumors. To determine the origin of elevated serum alpha 1,3fucosyltransferase, blood samples were obtained from both the drainage vein and the artery in patients with different stages of colorectal cancer at surgery. The enzyme levels in all samples from the drainage vein were found to be higher than the levels in the artery that fed the tumor. Hence, the origin of elevated alpha1,3fucosyltransferase in serum was thought to be the tumor rather than the liver that is the normal source of serum alpha1,3fucosyltransferase. When serum samples not only from colorectal cancer patients but also from patients with gastric, liver, lung, pancreas, bladder and esophagus cancer were treated with anti-FUTVI antibody, the measured activities of alpha1,3fucosyltransferase were markedly reduced. Further, secretion of alpha1,3fucosyltransferase from human colorectal carcinoma cells was also detected in the culture medium by Western immuno-blot analysis with anti-FUTVI antibody.

A new method for assaying adhesion of cancer cells to the greater omentum and its application for evaluating anti-adhesion activities of chemically synthesized oligosaccharides

A new ex vivo method for assaying adhesion of cancer cells to the greater omentum has been developed using mouse greater omentum and [3H]labelled human gastric and mouse colorectal cancer cells. Since the adhesion rates were found to increase up to 18 h and labelled cells seemed to be stable during the period, the present method could be useful for investigating adhesion of cancer cells to the greater omentum, which must occur at the first step of the peritoneal dissemination. The adhesion of cancer cells to the greater omentum was inhibited by a series of chemically synthesized oligosaccharides and Gal beta1,3[3OMeGal beta1,4GlcNAc beta1,6]alphaBn was found to be the best inhibitor. The anti-tumor effect of this novel tetrasaccharide in vivo was shown in preliminary experiments using Balb/c mice and colon26 cells.

A novel method for determination of alpha1,6fucosyltransferase activity using a reducing oligosaccharide from egg yolk as a specific acceptor

A new method for determination of alpha1,6fucosyltransferase activity has been described. Recently, the disialyl-biantennary undecasaccharide was prepared in high yield from egg yolk [(1996), Carbohydr Lett 2: 137-42]. By treatment of this oligosaccharide with neuraminidase and beta-galactosidase, we readily obtained an asialo-agalacto-biantennary heptasaccharide (GlcNAcbeta 1,2Manalpha1,6[GlcNAcbeta1,2Manalpha1,3]Manbeta1 ,4GlcNAcbeta1,4GlcNAc). Using this asialo-agalacto-oligosaccharide as an acceptor, fucosyltransferases from human plasma and extracts of various human hepatoma cell lines were assayed in the presence of GDP-[3H]fucose. The reaction mixture was applied to a column of GlcNAc-binding, Psathyrella velutina lectin coupled gel. All the fucosylated acceptor were bound to the column which was eluted with 50 mM GlcNAc. Structural analyses revealed that only the innermost GlcNAc residue of the acceptor was fucosylated through an alpha1,6-linkage, and the oligosaccharide prepared could be used as a specific acceptor for alpha1,6fucosyltransferase. The present method was used to screen plasma alpha1,6fucosyltransferase in several patient groups, and significantly elevated activities were found in samples from patients with liver diseases, including chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma.

Novel aspects of interaction between UDP-gal and GlcNAc beta-1,4-galactosyltransferase: transferability and remarkable inhibitory activity of UDP-(mono-O-methylated gal), UDP-Fuc and UDP-man

Four mono-O-methylated and one mono-O-acetylated UDP-D-Gal analogues and UDP-L-Fuc were synthesized. 2-O-Methyl-D-galactose residue was enzymatically transferred to give 2'-O-methyllactosaminide in high yield. UDP-Fuc and UDP-Man showed potent inhibitory activities against beta-1,4-galactosyltransferase. Structural requirement and steric allowance for the ground and transition states of the enzyme reaction were discussed.

Alpha 2-->3sialyltransferase associated with the synthesis of CA 19-9 in colorectal tumors

BACKGROUND

A novel assay method specific for alpha 2-->3sialyltransferase that seems to be responsible for the synthesis of CA 19-9 antigen was developed and the levels of the enzyme in colorectal tumor tissues were measured and compared with the levels of alpha 1-->4fucosyltransferase and the CA 19-9 antigen.

METHODS

Lacto-N-biose I (Gal beta 1-->3GlcNAc beta, Lewis(c) [Le(c)]) and 6-O-methyl-Le(c) (Gal beta 1-->3[6OMe]GlcNAc beta) were synthesized and covalently attached to bovine serum albumin (BSA). These two substrates were incubated with extracts from colorectal tissues in the presence of cytidine 5'-monophospho-N-acetylneuraminic acid (CMP-NeuAc) and their resulting products were detected by a sequential use of anti-BSA monoclonal antibody-coated beads and 125I-labelled anti-sialylated Le(c) antibody. Levels of alpha 2-->3sialyltransferase and alpha 1-->4fucosyltranferase activities and CA 19-9 antigen were measured in the extracts from colorectal tumors and their adjacent normal tissues.

RESULTS

6-O-Methyl-Le(c)-BSA showed a strong acceptor activity compared with Le(c)-BSA and was used as a specific acceptor for alpha 2-->3sialyltransferase. Similar elevation patterns alpha 2-->3sialyltransferase activities and CA 19-9 antigen levels were observed in tumor extracts but no clear correlation was present between the level of alpha 1-->4fucosyltransferase activities and CA 19-9 antigen levels were observed in tumor extracts but no clear correlation was present between the level of alpha 1-->4fucosyltransferase activities and CA 19-9 antigen levels in the same extracts.

CONCLUSIONS

The accumulation of CA 19-9 antigen in colorectal tumors might be caused mainly by the activation of alpha 2-->3sialyltransferase but not by that of alpha 1-->fucosyltransferase.

Fucosyltransferase of the peritoneum contributed to the adhesion of cancer cells to the mesothelium

Adhesion molecules associating with peritoneal dissemination were investigated using human gastric (MKN45 and MKN74) and colon (KM12C and KM12SM) cancer cells and the mouse peritoneum. Adhesion of cancer cells to the peritoneum was determined by a recently reported novel ex vivo method. MKN45 cells established from poorly differentiated adenocarcinoma with less glycosylated sugar chains on their cell surface showed higher adhesion activities to the peritoneum ex vivo and produced large amount of metastases in the abdominal cavity of nude mice, whereas MKN74 cells from differentiated adenocarcinoma with more glycosylated sugar chains showed slightly low adhesion activity. KM12SM cells with highly metastatic potential to liver showed fairly low adhesion activity to the peritoneum compared with KM12C cells. The mouse peritoneum was found to contain alpha 1 --> 2, alpha 1 --> 3, and alpha 1 --> 4 fucosyltransferases, and adhesion of cancer cells was observed to the cellulose ester membrane, on which partially purified alpha-fucosyltransferases from mouse peritoneum were immobilized. The adhesion of cancer cells to fucosyltransferase-immobilized membrane was specifically inhibited by the addition of oligosaccharides and glycoproteins, which could serve as substrates for alpha-fucosyltransferases. These results indicate the contribution of alpha-fucosyltransferases to the adhesion of disseminated cancer cells to the peritoneum and support the possibility of antiadhesion therapy of peritoneal dissemination by treatment with substrates for alpha-fucosyltransferases.

Parallel changes in the blood levels of abnormally-fucosylated haptoglobin and alpha 1,3 fucosyltransferase in relationship to tumour burden: more evidence for a disturbance of fucose metabolism in cancer

Levels of an abnormally-fucosylated form of the serum glycoprotein, haptoglobin (FHp) and an enzyme, alpha 1,3 fucosyltransferase (FT) have been measured in blood specimens from women with carcinoma of the ovary or breast who are undergoing chemotherapy. The levels of FHp and FT increased if the women had progressive disease and decreased if they showed complete response to therapy. The statistical correlation between the blood concentrations of these two substances is very strong (P less than 0.0001, chi 2 test). These results and recent studies of fucosyltransferases and cell adhesion molecules from other laboratories, suggest that there are important changes in fucose metabolism in cancer which are worthy of further investigation.

Combined chemical-enzymic synthesis of a dideoxypentasaccharide for use in a study of the specificity of N-acetyl-glucosaminyltransferase-III

The biantennary oligosaccharide glycoside beta-D-GlcpNAc-(1----2)-alpha-D- Manp-(1----3)- [beta-D-GlcpNAc-(1----2)-alpha-D-Manp-(1----6)]-beta-D-Manp- OR is a potential substrate for N-acetylglucosaminyltransferases (GlcNAcTs) III-V. The dideoxypentasaccharide glycoside beta-D-GlcpNAc-(1----2)-4- deoxy-alpha-D-lyxo-Hexp-(1----3)- [beta-DGlcpNAc-(1----2)-6-deoxy-alpha-D-Manp-(1----6)] beta-D-Manp-O(CH2)7CH3 (5), where the hydroxyl groups that would be acted on by GlcNAcTs IV and V have been removed, was prepared as a possible specific acceptor for GlcNAcT-III. The strategy involved the chemical synthesis of beta-D-GlcpNAc-(1----2)-4-deoxy-alpha-D-lyxo-Hexp-(1----3)-] 6- deoxy-alpha-D-Manp-(1----6)]-beta-D-Manp-O)CH2)7CH3 and then addition of the last GlcpNAc residue using partially purified GlcNAcT-II from rabbit liver. Preliminary results, using detergent extracts from rat kidney, indicate that 5 is an acceptor for a GlcNAcT whose identity remains to be established.

Synthesis of benzyl O-(2-O-methyl-beta-D-galactopyranosyl)-(1----3)-2- acetamido-2-deoxy-beta-D-glucopyranoside [benzyl 2'-O-methyllacto-N-bioside I], and its higher saccharide containing an O-(2-O-methyl-beta-D- galactopyranosyl)-(1----3)-2-acetamido-2-deoxy-beta-D-glucopyranosyl group as a potential substrate for (1---4)-alpha-L-fucosyltransferase

Treatment of benzyl O-beta-D-galactopyranosyl-(1----3)-2-acetamido-2- deoxy-4,6-O-isopropylidene-beta-D-glucopyranoside with tert-butylchlorodiphenylsilane afforded the 6'-O-tert-butyldiphenylsilyl ether, which was converted into the 3',4'-O-isopropylidene derivative. Methylation and subsequent removal of protecting groups afforded benzyl O-(2-O-methyl-beta-D-galactopyranosyl)- (1----3)-2-acetamido-2-deoxy-beta-D-glucopyranoside (7). The trisaccharide methyl O-(2-O-methyl-beta-D-galactopyranosyl)-(1----3)-O-(2- acetamido-2-deoxy-beta-D-glucopyranosyl)-(1----3)-beta-D-galactopyranosi de (17) and the tetrasaccharide O-(2-O-methyl-beta-D-galactopyranosyl)-(1----3)-O-(2-acetamido-2-deoxy-b eta-D- glucopyranosyl)-(1----3)-O-beta-D-galactopyranosyl-(1----4)-D-glucopyran ose (32), both containing the 2'-O-methyllacto-N-biose I unit at the nonreducing end, were synthesized, and the structures of 7, 17, and 32 were confirmed by 13C-n.m.r. spectroscopy.

Use of benzyl 2-acetamido-2-deoxy-3-O-(2-O-methyl-beta-D-galactosyl)-beta- D-glucopyranoside [2'-O-methyllacto-N-biose I beta Bn] as a specific acceptor for GDP-fucose: N-acetylglucosaminide alpha(1----4)-L-fucosyltransferase

A synthetic substrate, benzyl 2-acetamido-2-deoxy-3-O-(2-O-methyl-beta-D- galactopyranosyl)-beta-D-glucopyranoside, was demonstrated to be a specific acceptor for the Lewis blood group-specified alpha(1----4)-L-fucosyltransferase from human saliva and stomach mucosa. The fucosyl linkage of the product resulting from the use of this substrate isolated by paper chromatography was characterized by hydrolysis with specific alpha(1----3)/(1----4)-L- fucosidase. The product can be separated by adsorption onto the reverse-phase cartridge and recovered by one-step elution with methanol. The enzymatic properties of alpha(1----4)-L-fucosyltransferase from saliva and stomach mucosa have also been examined using this substrate.

An enzyme-linked immunosorbent assay for the measurement of Lewis blood-group alpha-(1----4)-fucosyltransferase activity

An enzyme-linked immunosorbent assay (ELISA) has been developed for the Lewis blood-group associated alpha-(1----4)-fucosyltransferase activity. Microtiter plates coated with the bovine serum albumin conjugate of a synthetic beta-D-Galp-(1----3)-beta-D-GlcpNAc disaccharide are incubated with a fucosyltransferase preparation in the presence of guanosine 5'-diphosphofucose. The resulting immobilized Lewis-a active trisaccharide beta-D-Galp-(1----3)-[alpha-L-Fucp-(1----4)]-beta-D-GlcpNAc is then detected and quantitated using a monoclonal anti-Lewis-a antibody. Product formation detected in this manner is linear with time, proportional to enzyme activity, and reproducibly quantitated in the 50-400 fmol range.

Serum alpha(1----3)-L-fucosyltransferase, carcinoembryonic antigen, and sialyl Lewis X-i antigen levels in lung cancer

Serum alpha(1----3)-L-fucosyltransferase activity was measured in 58 patients with lung cancer, 27 benign diseases, and in 100 healthy controls. The levels of enzyme activity were significantly higher in the sera of patients with cancer when compared to those in benign diseases and healthy controls. The elevation of the enzyme activity correlated with the clinical stages and to the size of the primary tumors. Follow-up studies with various stages showed that the enzyme activity was useful in tracking the clinical course of disease after surgery. To evaluate the usefulness of this enzyme as a diagnostic marker, carcinoembryonic antigen (CEA) and sialyl Lewis X-i antigen levels were also measured. The results indicate that alpha(1----3)-L-fucosyltransferase could be a more specific tumor marker than such tumor-associated antigens in lung cancer.

Tumor-related elevation of serum (alpha 1----3)-L-fucosyltransferase activity in gastric cancer

(alpha 1----3)-L-Fucosyltransferase activity was measured in serum samples from 90 gastric cancer patients, 10 patients with benign diseases and 100 healthy controls. The enzyme activity was significantly elevated in the serum samples of patients with cancer compared to those from patients with benign diseases (P less than 0.01) and healthy controls (P less than 0.001). The elevation of the enzyme activity was found to correlate strongly with the clinical stage of disease. The sensitivity of (alpha 1----3)-L-fucosyltransferase was also demonstrated to be high in comparison with the tumor-associated antigens, such as carcinoembryonic antigen and sialylated Lewis X-i. Follow-up studies of (alpha 1----3)-L-fucosyltransferase in 11 cancer patients with disease at different stages showed that the enzyme activity could be useful for monitoring the post-surgical course of the disease. These results suggest that (alpha 1----3)-L-fucosyltransferase activity has a clinically important potential as a tumor marker in gastric cancer.

Cancer-associated elevation of alpha(1----3)-L-fucosyltransferase activity in human serum

GDP-fucose:N-acetylglucosaminide alpha(1----3)-L-fucosyltransferase activity was measured in sera of patients with various cancers using a synthetic substrate, N-acetyl-2'-O-methyllactosamine, as an acceptor. One hundred twenty-four of the 169 patients showed significantly high levels of the enzyme activity when compared to healthy controls, irrespective of the location of their tumor. However, enzyme levels were in the normal range in patients with non-neoplastic diseases, such as infectious disease, liver disease, and other inflammatory problems as well as in leukemic patients. The chromatofocusing profile of the enzyme using PBE-94 gel over a pH gradient from pH 6.0 to 4.0 demonstrated that the level of enzyme eluted at pH 5.4 was markedly elevated in the sera of stomach and ovarian cancer patients. A correlation was established between alpha(1----3)-L-fucosyltransferase activity and the presence of malignancy which may be used to evaluate the utility of the enzyme as a tumor marker.

The presence of CA19-9 in serum and saliva from Lewis blood-group negative cancer patients

Eighteen cancer patients showed high levels of CA19-9 in sera, even though the blood-group phenotypes of their red blood cells were Le(a-b-). Seven of these patients (group I) were determined as Le(a-b-) from both red blood cells and saliva consistently, whereas eleven other patients (group II) secreted either Le(a) or Le(b) antigen in saliva and showed the expression of incompatible Lewis blood-group antigens. GDP-fucose: N-acetyl-glucosaminide alpha(1----4)-L-fucosyltransferase was demonstrated to be present in salivas from both group I and group II. These results suggest that a cancer-associated alteration of Lewis blood-group antigen expression occurs in cancer patients.

Synthesis of the isomeric trisaccharides, methyl O-alpha-L-fucopyranosyl- (1----3, 4, and 6)-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1----3)-beta- D-galactopyranoside

Benzylation of methyl 3-O-(2-acetamido-4,6-O-benzylidene-2-deoxy-beta-D- glucopyranosyl)-2,4,6-tri-O-benzyl-beta-D-galactopyranoside with benzyl bromide in N,N-dimethylformamide in the presence of sodium hydride afforded methyl 3-O- (2-acetamido-3-O-benzyl-4,6-O-benzylidene-2-deoxy-beta-D-glucopyranosyl) -2,4,6- tri-O-benzyl-beta-D-galactopyranoside (3). Reductive ring-opening of the benzylidene group of 3 gave methyl 3-O-(2-acetamido-3,6-di-O-benzyl-2-deoxy-beta-D- glucopyranosyl)- 2,4,6-tri-O-benzyl-beta-D-galactopyranoside (4). Cleavage of the 4,6-acetal group of 3 with hot, 80% aqueous acetic acid afforded the diol (5). Compounds 3, 4, and 5 were each subjected to halide ion-catalyzed glycosylation with 2,3,4-tri-O-benzyl-alpha-L-fucopyranosyl bromide to produce the corresponding trisaccharide derivatives, which, on catalytic hydrogenation, furnished the title trisaccharides, respectively.

Synthesis of 2-acetamido-2-deoxy-4-O-(2-O-methyl-beta-D-galactopyranosyl)- D-glucopyranose (N-acetyl-2'-O-methyllactosamine)

1,3,4,6-Tetra-O-acetyl-2-O-methyl-D-galactopyranose, prepared from known methyl 6-O-acetyl-3,4-O-isopropylidene-beta-D-galactopyranoside, was treated with hydrogen bromide in dichloromethane to afford 3,4,6-tri-O-acetl-2-O-methyl-alpha-D-galactopyranosyl bromide. Condensation with benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-alpha-D-glucopyranoside in acetonitrile in the presence of mercuric cyanide gave an approximately 1:1 mixture of benzyl 2-acetamido-3, 6-di-O-benzyl-2-deoxy-4-O-(3,4,6-tri-O-acetyl-2-O-methyl-beta- (8) and -alpha-D-galactopyranosyl)-alpha-D-glucopyranoside. O-Deacetylation and catalytic hydrogenolysis of the benzyl group furnished 2-acetamido-2-deoxy-4-O-(2-O-methyl-beta- and alpha-D-galactopyranosyl)-D-glucopyranose. Alternatively, benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-4-O-beta-D- galactopyranosyl-alpha-D-glucopyranoside was treated with tert-butyldiphenyl-chlorosilane in N,N-dimethylformamide, in the presence of imidazole, to give a 6'-O-tert-butyldiphenylsilyl intermediate that was in turn converted into its 3',4'-O-isopropylidene acetal. Methylation with methyl iodide-silver oxide in N,N-dimethylformamide, followed by removal of the silyl and isopropylidene groups gave benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-4-O-(2-O-methyl-beta-D- galactopyranosyl)-alpha-D-glucopyranoside, which was further characterized as its triacetate 8.

Elevated activities of blood group Le gene dependent alpha(1----3)-L-fucosyltransferase in human saliva of Lewis negative patients with epithelial ovarian cancer

Levels of alpha(1----3)-L-fucosyltransferase activities were measured in salivas of patients with ovarian cancer. GDP-L-Fuc:GlcNAc alpha(1----3)-fucosyltransferase was found elevated in patients known to have epithelial ovarian cancer, irrespective of their ABH and Lewis blood group phenotypes. GDP-L-Fuc: Glc alpha(1----3)-fucosyltransferase was also elevated in both Lewis positive and negative patients, although the enzyme activity was very low or absent in Lewis negative healthy controls.

alpha-L-fucosidase from aspergillus niger: demonstration of a novel alpha-L-(1----6)-fucosidase acting on glycopeptides

An alpha-L-fucosidase which hydrolyzes fucose from alpha-(1----6)-linkage to N-acetylglucosamine was found in Aspergillus niger. The enzyme was purified by affinity chromatography with bovine IgG glycopeptide-Sepharose 4B. The enzyme preparation released fucose from bovine IgG glycopeptide and fucosylated asialoagalactofetuin, but failed to cleave 1----2, 1----3 or 1----4 linkages of alpha-L-fucosides.