Alpha-L-fucosyltransferases in human serum from donors of different ABO, secretor and Lewis blood-group phenotypes

Serum levels of glycosyltransferases and related glycoproteins as indicators of cancer: biological and clinical implications

Many studies have suggested that malignant transformation is associated with fundamental changes in the cell surface; similar changes have been described for normal stem cells and cells of embryonic or fetal origin. There is now evidence that the tumor cell secretes or sheds glycoproteins and glycosyltransferases into the surrounding medium and into serum. There are claims that some of these serum glycoproteins and glycosyltransferases are associated with, or specifically related to, the extent of tumor growth and may serve as a cancer marker. A cancer-associated galactosyltransferase isoenzyme (GT-II) has been described and purified. Different isoelectric forms of fucosyltransferase have also been described as indicative of malignancy. The articles to be published in CRC Critical Reviews in Clinical Laboratory Sciences will analyze the evidence for the association of these membrane factors with tumor growth. In order to better understand the possible significance of altered glycoproteins and of increased or different forms of glycosyltransferases during tumor growth, recent data on glycoprotein synthesis will be discussed including the new concepts on the control of glycoprotein synthesis through lipid intermediates. The possible mechanisms whereby malignant transformation could alter glycoprotein synthesis will be discussed with particular emphasis on the significance of these alterations to the biology of the malignant cell. Changes in surface membrane glycoproteins have long been implicated in the ability of a cell to metastasize. Secretion and/or shedding of the cell surface may also be important in the process of metastasis and in altering the host immune response. Detection and the study of these "shed" materials in patients appear to be indicating a new approach to cancer biology detection and therapy.

An initial step in the induction of cancer, the loss of histone H1 from chromosomes - a hypothesis

Unexpected blood group antigens of the P and ABO blood group systems have been found on gastric carcinoma cells of some individuals whose red cells did not possess the antigens and whose sera contained the corresponding antibodies. On the basis of the known biosynthetic pathways leading to the synthesis of the antigens, and on the concept that the blood group genes involved control the structure of glycosyltransferases, it seems that the individuals possess the respective glycosyltransferases structural genes which are not expressed in normal tissues. However, the genes have become expressed in the carcinoma cells.

Modified procedure for detection of GDP-L-fucose:galactoside 2'-fucosyltransferase

A modified method was developed for determination of GDP-L-fucose: galactoside 2'-fucosyltransferase in human serum which employed O-nitrophenyl-beta-D-galactopyranoside, phenyl-2-acetamido-2-deoxy-3-O-beta-D-galactopyranosyl-alpha-D-galactopyranoside, or phenyl-beta-D-thiogalactopyranoside as acceptor. Products were identified and characterized by thin layer chromatography with authentic reference compounds and by hydrolysis with alpha-(1 leads to 2)-L-fucosidase. The principal advantages of this method over the previous procedure which used aryl galactoside acceptors, are elimination of the need for a radiochromatogram scanner to locate reaction products and a reduced development time for chromatography. These results in substantial time and cost savings. Moreover, our system can simultaneously monitor possible competing reactions which may interfere with determination of alpha-2-L-fucosyltransferase activity. These include phosphorylase and alpha-L-fucosidase activities and incorporation of [14C]-alpha-L-fucose into endogenous acceptors of enzyme preparations. thus, this modified procedure will facilitate determination of alpha-2-L-fucosyltransferase.

An H-deficient blood with normal H transferase levels

An H-deficient blood is described which, unlike other H-deficient, Bombay and para-Bombay bloods, has normal H transferase levels. In previous examples of Bombay and para-Bombay phenotypes the absence of H transferase has explained the lack of H substrate and therefore the weak A and B antigens which are characteristic of these phenotypes. This explanation obviously does not hold in the case described here and it is proposed that the biochemical block must be further back, either in the enzymes synthesising the oligosaccharide chains or in those making the GDP-fucose substrate for the H and the Le gene-specified fucosyltransferases. Inhibition of the synthesis of Leb substance, as well as H substance, although the saliva of the propositus contains the Le gene-specified transferase, supports this proposition.

alpha-L-Fucosyltransferases related to biosynthesis of blood group substances in human Saliva

alpha-L-Fucosyltransferases were demonstrated in human saliva which catalyze the transfer of L-fucose from GDP-L-[14C]-fucose to oligosaccharides from human milk. An alpha-(1 yields 4)-L-fucosyltransferase that synthesizes lacto-N-fucopentaose II and lacto-N-difucohexaose I from lacto-N-tetraose and lacto-N-fucopentaose I, respectively, was detected in saliva samples of Le(a--b+) secretors and Le(a+b--) non-secretors in which Lea substance was secreted. This enzyme activity was demonstrable neither in saliva samples of Le(a--b--) secretors nor non-secretors. An alpha-(1 yields 2)-L-fucosyltransferase, that synthesizes lacto-N-fucopentaose I from lacto-N-tetraose, was detected in saliva samples from Le(a--b+) secretors which secreted H and Leb substances and from Le(a--b--) secretors which secreted only H substance. An alpha-(1 yields 3)-L-fucosyltransferase was present in all saliva samples of different ABO and Lewis blood groups, irrespective of their ABH secretor status of the donors. The fucosyltransferases in saliva were activated by Mn++ or Mg++ ions, and were inhibited by ATP, GTP and EDTA. They had a broad pH optimum between pH 5.0 and 6.5.

Purification and properties of adenosine deaminase in normal and hereditary hemolytic anemia with increased red cell activity

Red cell adenosine deaminase from normal subjects and from a patient with hereditary hemolytic anemia with a 40-fold increase in activity were purified using antibody affinity chromatography. The purified enzymes were completely homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. There were no differences in the molecular weight, specific activity, polyacrylamide gel electrophoresis, Michaelis constant for adenosine, inhibition constant for guanylurea, utilization of 2-deoxyadenosine, thermal stability, optimum pH, immunological reactivity, amino acid composition and tryptic peptide mapping. These results strongly suggest that increased red cell adenosine deaminase activity is caused by an overproduction of a structurally normal enzyme.

Probable biosynthetic pathway for the synthesis of the B antigen for Bh variants

Red cells and serum from two Bh variants (B+H-cells) have been investigated for B and H blood group glycosyltransferases. The H enzyme could not be detected using either type 1 or type 2 chain acceptors. The B enzyme was present in normal amount when 2'-fucosyllactose was used as substrate, neither 6'-fucosyllactose nor 6'-fucosyllactosamine could act as acceptors for the B enzyme. Upon treatment of the Bh red cells by the B-degrading enzyme from Trichomonas foetus the B antigen was destroyed while H determinants were uncovered (B-H + cells). The cells thus treated could be further converted into A&H-red cells by the action of the A transferase from human blood group A serum. Previous treatment of the B-H + cells by the H-degrading enzyme from T. foetus, however, led to B-/-erythrocytes and prevented their conversion into A red blood cells by the A enzyme. The results clearly demonstrate that, as found in normal B individuals, the B antigen from Bh cells is built up from the H precursor and provide additional evidence that H is not a completely silent gene in Bh individuals.

Delineation of fucosyltransferase activities with thiol reagents

The thiol reagent dithiothreitol inhibits the activity of a core GDP-fucose-N-acetylglucosaminide alpha-6-fucosyltransferase in plasma and blood-cell homogenates, while promoting the activity of alpha-2- and alpha-3-fucosyltransferases. The latter enzymes catalyse transfer of fucose on to terminal galactose and subterminal N-acetylglucosamine residues respectively. A thiol-blocking reagent N-ethylmaleimide does not affect the activity of the alpha-6-fucosyltransferase, but inhibits the other two enzymes. These results indicate the presence of a critical disulphide linkage in the alpha-6-fucosyltransferase, and provide a means of delineation of different fucosyltransferases.

Decrease of human serum fucosyltransferase as an indicator of successful tumor therapy

Surgical removal of colon carcinomas leads to a decrease in the rate of incorporation of [14C]fucose into its endogenous acceptor in human serum; normal incorporation rates are attained within 14 days. A similar time course has been determined for alpha2- and alpha3-fucosyltransferase when either desialo- or desialodegalactofetuin are employed as exogenous acceptors. A correlation has also been seen between transferase activity and the therapeutic response of patients with breast cancer. These results indicate that the determination of fucosyltransferase activity can facilitate the diagnosis of neoplasia, and the success of surgery, chemotherapy, or radiation.

Serological studies of the H activity of Oh red cells with various anti-H reagents

Several examples of Oh cells have been investigated with various anti-H reagents. After enzyme treatment of the cells with either papain or neuraminidase, very high titres were obtained, particularly with some preparations of Ulex europeus. Fractionation of anti-H Ulex showed that the anti-H component inhibitable by L-fucose required papain treatment of the Oh cells for optimal activity whereas the component not inhibitable by L-fucose agglutinated preferentially Oh cells treated with neuraminidase. The anti-H lectin Cytisus sessifolius which is not inhibitable by L-fucose gave no reaction with papain-treated Oh cells but reacted well when the Oh cells were treated with neuraminidase. Normal O cells were almost equally well agglutinated by the lectins when treated by either of the two enzymes. That the various lectin components activated by enzymes had H specificity was shown by the fact that their activity was inhibited by purified H substance, partially inhibited to L-fucose and 2-fucosyllactose and not at all by purified Lea substance and non-secretor salivas. In spite of the high titres obtained with Oh cells by the enzyme technique, the amount of H present on the red cells, judged by inhibition tests, in comparison with normal group O cells was very small.

Occurrence of two fucosyltransferase activities at the outer surface of rat lymphocytes

To demonstrate the existence of ectofucosyltransferase activities on the outer surface of rat lymphocytes, we measured fucosyltransferase activities on whole cells using procedures enabling us to exclude the possibility of misleading results due to precursor hydrolysis and intracellular utilization of the free fucose, and to take into account the contamination by intracellular enzymes freed by the small percentage of broken cells. The described ectofucosyltransferases are able to catalyze the transfer of fucosyl residues from GDP-fucose to the endogenous membrane acceptors but the transfer activity towards exogenous acceptors is restricted to low molecular weight compounds. Use of galactose and di-N-acetylchitobiose as exogenous acceptors and concomitant study of the specific inhibition by N-ethylmaleimide enabled us to detect both types of ectofucosyltransferases: a GDP-fucose: galactoside ectofucosyltransferase and a GDP-fucose: N-acetylglucosaminide ectofucosyltransferase.

Evaluation of two plasma fucosyltransferases as marker enzymes in non-Hodgkin's lymphoma

Levels of two fusosyltransferases were measured in plasmas of patients with non-Hodgkin's lymphoma at different phases of the disease. The level of a GDP-fucose: galactoside fucosyltransferase (EC 2.4.1.69) was found elevated in nonresponding patients and was correlated with estimated tumor burden. Enzyme levels in the normal range were found in patients in remission, maintained on chemotherapy, or unmaintained. The plasma level of a GDP-fucose; N-acetylglucosaminide fucosyltransferase (EC 2.4.1.68) was elevated in all individuals receiving drug therapy regardless of diesease status, but returned to normal levels during unmaintained remissions.

Some properties of sialyltransferase in plasma and lymphocytes of patients with chronic lymphocytic leukemia

Some properties of sialyltransferase activity in plasma and lymphocytes from patients with chronic lymphocytic leukemia were compared. Three distinct enzyme fractions were identified in plasma: (1) cation independent, irreversibly bound to agarose; (2) cation dependent, weakly bound to agarose; (3) strongly bound to agarose, lost upon dialysis. Lowering of the peripheral lymphocyte count by leukapheresis markedly decreased the level of serum sialyltransferase, suggesting the circulating lymphocyte is a source of the serum enzyme. The enzyme solubilized by detergent from lymphocytes showed a substantially lower Km for CMP-sialic acid than did the serum enzyme, was less sensitive to several inhibitors, was not irreversible bound to Agarose, and had a substantial cation requirement. The enzyme solubilized from the lymphocyte therefore generally resembles fraction 2 of serum.

Human blood-group A- and H-specified glycosyltransferase levels in the sera of newborn infants and their mothers

The level of blood-group A1-specified alpha,3'-N-acetyl-D-galactosaminyl-transferase in the serum of recently-delivered women was found to be appreciably lower than the level of this enzyme in the serum of non-pregnant adults and of newborn infants; a similar but less striking decrease was observed in the levels of the A2-specified alpha,3'-N-acetyl-D-galactosaminyltransferase and the H-specified alpha,2'-L-fucosyltransferase. Although the red cells of newborn infants are known to have relatively few A and H antigen sites, the serum of neonates was found to have a level of A1- and A2-dependent N-acetylgalactosaminyltransferases and H-dependent fucosyltransferase as high as, if not higher than, the serum of non-pregnant adults. This finding is compatible with the fact that the haemopoietic tissue contributes only about 20% of the serum transferase level.

A study of the salivary glycoprotein in cystic fibrosis patients and controls: fucose incorporation and protein pattern

The incorporation of fucose to glycoprotein acceptors prepared from the saliva of Cystic Fibrosis (CF) patients was compared with the incorporation into acceptors from controls. The CF acceptor glycoprotein incorporated significantly more fucose in the presence of either patients' or control plasma. The fucosyl transferase activity in the patients' plasma was not significantly different from controls. Fucosidase activity was similar also for both groups. The protein bands of the acceptor glycoproteins from the patients' saliva differed from those of the control in number and electrophoretic mobility. On the basis of these studies of fucose incorporation we propose that glycoprotein in the salivary secretion of CF patients are qualitatively different from normal.

Enzymatic synthesis of two fucose-containing glycolipids with fucosyltransferases of human serum

Lacto-N-neotetraosylceramide incubated with human serum fucosyltransferase preparations gave rise to two fucoglycolipids. The faster migrating fucoglycolipid I on the basis of its thin-layer chromatographic mobility, susceptibility to alpha(1 leads to 2) fucosidase from Trichomonas foetus, radio-immunoprecipitation with Ulex europeus lectin and studies with Oh (Bombay) sera was identified as H-active glycolipid (H-I). The most probable structure of fucoglycolipid II should be that with fucose linked alpha(1 leads to 3) to N-acetylglucosamine. Lactosylceramide, ceramide trihexoside and globoside were not substrates for human serum fucosyltransferases. Lacto-N-neotetraosyl ceramide served as a fucose acceptor for all serum preparations tested while asialoganglioside was a substrate only when serum preparations containing H-gene dependent alpha-2-L-fucosyltransferase were used. With asialoganglioside only one radioactive reaction product was formed.

Synthesis of p-nitrophenyl 2-acetamido-2-deoxy-O-beta-D-galactopyranosyl-beta-D-glucopyranosides

Reaction of p-nitrophenyl 2-acetamido-2-deoxy-4,6-O-(p-methoxybenzylidene)-beta-D-glucopyranoside (2) with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide (3) under the usual conditions, followed by removal of the p-methoxybenzylidene group and O-deacylation, produced crystalline p-nitrophenyl 2-acetamido-2-deoxy-3-O-beta-D-galactopyranosyl-beta-D-glucopyranoside (6). Starting from p-nitrophenyl 2-acetamido 3,4-di-O-acetyl-2-deoxy-beta-D-glucopyranoside, the synthesis of p-nitrophenyl 2-acetamido-2-deoxy-6-O-beta-D-galactopyranosyl-beta-D-glucopyranoside was also accomplished.

Action of glycosyl transferases upon "Bombay" (Oh) erythrocytes. Conversion to cells showing blood-group H and A specificities

Individuals of the rare "Bombay" (Oh) blood-group phenotype lacking, due to a genetic defect, the alpha(1-2)fucosyl transferase, which is responsible for converting blood-group H precursor substances to H-specific structures. Treatment with GDP-fucose and alpha(1-2)fucosyl transferase prepared from gastric mucosa of O individuals to transform native or ficin-treated "Bombay" erythrocytes into cells phenotypically resembling O cells. The transformation was achieved, however, after prior incubation of the "Bombay" erythrocytes with neuraminidase, indicating that blood-group H precursor molecules on the surface of these cells are masked by sialyl residues. Blood-group A specificity was conferred upon neuraminidase-treated "Bombay" cells by enzymatic transfer of alpha-N-acetylgalactosamine residues, in addition to alpha-fucose residues.

The action of group Bm or CisAB sera on group O red cells in the presence of UDP-D-galactose

Group B and AB sera, acting on O red cells in the presence of UDP-galactose, each converted them into B active cells, which were agglutinated by anti-B human serum (1:512) at the titer of 128-fold, while group Bm and A-1 Bm sera, converted O red cells similarly incubated into B active cells, which were agglutinated by anti-B human serum (1:512) at the titer of 8- to 16-fold. This indicates that alpha-galactosyltransferase activity in Bm and A-1 Bm sera may be about 1/8-1/16 that in B and AB sera. Group CisAB sera, even after absorption of cold anti-B agglutinins with packed, washed group B red cells, did not convert O red cells in the presence of UDP-galactose in such a way that they might agglutinate against anti-B human serum.

Quantitative isolation and purification of blood group-active glycosphingolipids from human B erythrocytes

11.4 mg of a ceramide hexahexoside (B-I) and 16.4 mg of a ceramide octahexoside (B-II) as blood group B-active glycosphingolipids composed of glucose, galactose, N-acetylglucosamine and fucose (molar ratios 1:3:1:1 and 1:4:2:1 respectively) have been isolated from 6,400 ml of packed human B erythrocytes. This yield is greater by more than the 13-fold amount of B-I glycosphingolipid and the 20-fold amount of B-II glycosphingolipid which has hitherto been isolated from human erythrocytes. The B-active glycosphingolipids isolated represent about 0.04% of the erythrocyte membrane and in consequence must be regarded as the main representants of B properties of the erythrocytes as far as they have been investigated up to this time. This high yield was achieved by a simple and conservative erythrocyte membrane preparation without loss of serological activity and by the improvement of some chromatographical methods which permitted a high purification without the acetylation-deacetylation procedure. Purity was checked by gas-liquid chromatographical analysis of the sugars as their alditol acetates and by the hemagglutination inhibition technique. 1.7 x 10-8 g of each of these glycosphingolipids completely inhibit the agglutination of human B erythrocytes by 4 hemagglutination units of normal human anti-B sera. A ceramide tetrahexoside and a glycolipid fraction with a high H activity could also be isolated which possibly are blood group-intermediate substances. Lewis blood group-active glycosphingolipids characterized by the hemagglutination inhibition test and by passive hemagglutination are trace constituents of other glycosphingolipid fractions.

Assay of alpha-N-acetylgalactosaminyltransferases in human sera. Further evidence for several types of Am individuals

The study of the alpha-N-acetylgalactosaminyltransferase in the sera of 19 individuals belonging to the rare Am blood group makes it possible to confirm the heterogeneity of this phenotype established on genetical and immunological criteria. Two groups of subjects, Am and Ay, can be distinguished. For the individuals of the first group, named Am, 15 samples (7 families) have been studied, the phenotype is inherited as an allele at the ABO locus. 14 of these subjects, have an alpha-N-acetylgalactosaminyltransferase whose kinetic properties were similar to those of A1 subjects. In one family, however, the A transferase detected is of the A1 type. On a quantitative level, the enzyme activities of these sera only reached 30-50 percent of the average value observed for A1 or A2 subjects, respectively. These facts suggest the existence of a genetic inhibitor, possibly linked to the ABO locus, preventing either an A1 or A2 gene from acting at the level of some cellular lines and leading therefore to the recognition of phenotypes named A-m-A1 and A-m-A2. On the contrary, under the experimental conditions used, no alpha-N-acetylgalactosaminyl-transferase activity was detected among the four individuals of the second group, named A-y by Weiner et al. (37), and whose appeareance in siblings results from the action of a recessive modifying y-A gene.