Elevated activities of alpha-2-and alpha-3-fucosyltransferases in human serum as a new indicator of malignancy

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.

Occurrence of alpha 1-2-fucosylation in membrane glycoproteins of Morris hepatoma 7777 but not in liver. Aberrant type of fucosylation in a malignant tissue

A comparative study was undertaken to characterize the linkages of L-fucose in N-glycans of plasma membrane glycoproteins from Morris hepatoma 7777, host liver and kidney cortex, as well as from rat serum. After in-vivo radiolabelling of rats with L-[6-3H]fucose, the asparagine-linked carbohydrate chains were released from delipidated plasma membrane glycoproteins, as well as from serum glycoproteins, by enzymic digestion with peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase from Flavobacterium meningosepticum. They were then converted to their corresponding oligosaccharide alditols by reduction with sodium borohydride. Two specific alpha-L-fucosidases from almond emulsin and from Aspergillus niger, combined with affinity HPLC on immobilized Aleuria aurantia lectin were used to study the linkage of L-fucose in the oligosaccharide chains. Fucose alpha 1-2 linked to galactose, was present only in the plasma membrane of hepatoma 7777 (18% of total L-[3H]fucose in N-glycans), but was not expressed in host liver, kidney cortex and serum. None of the investigated sources contained an appreciable amount of fucose alpha 1-3/4 linked to N-acetyl-D-glucosamine. All the radioactively labelled oligosaccharides from host liver, kidney cortex and serum, but only 82% of these oligosaccharides from hepatoma, contained alpha-fucosyl residues linked at the C6 position of the proximal N-acetyl-D-glucosamine.

Distribution of glycosyltransferases among Golgi apparatus subfractions from liver and hepatomas of the rat

Glycosyltransferase activities of highly purified fractions of Golgi apparatus, plasma membrane and endoplasmic reticulum, all from the same homogenates, were analyzed and compared. Additionally, Golgi apparatus were unstacked and the individual cisternae separated into fractions enriched in cis, median and trans elements using the technique of preparative free-flow electrophoresis. Golgi apparatus from both liver and hepatomas were enriched in all glycosyltransferases compared to endoplasmic reticulum and plasma membranes. However, Golgi apparatus from hepatomas showed both elevated fucosyltransferase and galactosyltransferase activities but reduced sialyltransferase and dipeptidyl peptidase IV (DPP IV) activities compared to liver. Activity of N-acetylglucosaminyltransferase was approximately the same in both liver and hepatoma Golgi apparatus. With normal liver, sialyl- and galactosyltransferase activities and DPP IV showed a marked cis-to-trans gradient of activity. Fucosyltransferase was concentrated in two regions of the electrophoretic separations, one corresponding to cis cisternae and one corresponding to trans cisternae. N-Acetylglucosaminyltransferase activity was more widely distributed but the endogenous acceptor activity was predominantly cis. With hepatoma Golgi apparatus, the pattern for DPP IV was similar to that for liver but those of sialyl- and galactosyltransferases differed markedly from liver. Instead of activity increasing cis to trans, the activities for sialyl- and galactosyltransferases decreased. For fucosyltransferases, activity dependent on exogenous acceptor was medial whereas with endogenous acceptor, two activity peaks, cis and trans, still were observed. For N-acetylglucosaminyltransferase the pattern for hepatoma was similar to that for liver. The results indicate alterations in the distribution of glycosyltransferase activities within the Golgi apparatus in hepatotumorigenesis that may reflect altered cell surface glycosylation patterns.

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.

Developmental changes in the glycosylation and binding properties of human fibronectins. Characterization of the glycan structures and ligand binding of human fibronectins from adult plasma, cord blood and amniotic fluid

Fibronectins from human adult plasma, fetal plasma and from amniotic fluid obtained during early and late gestation were compared with respect to (i) their reactivity with lectins, (ii) their binding to the physiological ligands gelatin and heparin, and (iii) the role of the carbohydrate residues in the binding to these two ligands. The two fibronectin isoforms displayed distinct developmental differences in both glycosylation and binding properties: (i) Proportions of tri/tetraantennary complex glycans compared to the fraction of biantennary structures, as inferred from the reactivity with concanavalin A, were highest in amniotic fluid fibronectin from late pregnancy, lower in amniotic fluid fibronectin from early gestation, and even lower in fetal and adult plasma fibronectins. Likewise, fucose (alpha 1-6) linked to the innermost N-acetylglucosamine of the chitobiosyl core, defined by reactivity with Lens culinaris agglutinin (LCA), was present primarily in amniotic fluid fibronectin, and decreased in content during gestation from the 2nd. to the 3rd. trimenon. Both fetal and adult plasma fibronectins were only weakly reactive with LCA, indicating a low content of (alpha 1-6) linked fucose residues. After prior treatment with sialidase, both plasma and amniotic fluid fibronectins strongly reacted with erythrocyte phytohaemagglutinin (E-PHA), indicating that both fibronectin isoforms contain bisecting (beta 1-4) N-acetylglucosamine residues. Amniotic fluid fibronectins showed much greater reactivity than adult and fetal plasma fibronectins with wheat germ agglutinin; binding of this lectin to amnion fluid fibronectins was not decreased by desialylation indicating the presence of poly(N-acetyllactosamine) units. Whereas amniotic fluid fibronectins were strongly reactive with peanut agglutinin, neither adult nor fetal plasma fibronectins did bind to this lectin unless after prior desialylation. Hence, both fibronectin isoforms contain O-glycan residues that are fully sialylated in fetal and adult plasma fibronectins, but only partly sialylated in amniotic fluid fibronectins. According to these differences, glycosylation of plasma and amniotic fluid fibronectins is under developmental regulation. (ii) Amniotic fluid fibronectins had a significantly lower binding activity for both heparin and gelatin than plasma fibronectins. Moreover, amnion fibronectin from late gestation displayed a significantly lower binding to these two ligands than amnion fibronectin from early gestation. Fetal plasma fibronectins had a lower binding activity for gelatin than adult plasma fibronectin. (iii) Treatment of fibronectins with sialidase, fucosidase and removal of N-glycans with endoglycosidases H and F did not affect binding to gelatin and heparin, indicating that the interaction of plasma and amnion fibronectin with these two ligands is not influenced by their oligosaccharide moieties.

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.

Activation energy and lectin affinity chromatography of gamma-glutamyltransferase as a marker for enzyme heterogeneity

Lectin affinity chromatography of gamma-glutamyl transferase (GGT,EC 2.3.2.2) is able to detect differences in the carbohydrate moiety of the enzyme. Binding of tissue GGT towards lectins is significantly different from serum GGT, showing increased galactosylation in tissue forms. Kidney GGT is less glycosylated than GGT from other tissues (liver, pancreas, prostate, vesiculae seminales). Increases in sialic acid content of GGT are associated with an increase in the activation energy of the catalyzed reaction. Differences in galactose, fucose and N-acetylhexosamine content induce much smaller effects on activation energy. In liver diseases, serum GGT is characterized by an altered affinity against lectins recognizing galactose, fucose and N-acetyglucosamine and by increased activation energy. In patients with liver disease, use of fixed temperature conversion factors can lead to erroneous calculations of serum GGT enzyme activity (errors up to 13.3%).

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.

Lectin-affinity chromatography of serum gamma-glutamyltransferase in liver disease

The variation of the carbohydrate chain of gamma-glutamyltransferase was studied in 45 liver patients by means of lectin affinity chromatography. Five lectins were used: concanavalin A, Ricinus communis I and II, Maclura pomifera and Ulex europaeus agglutinin. The binding towards Con A was shown to be independent from the binding towards the other lectins. Parallel variations of binding results against the galactose- and fucose-recognizing lectins were obtained. In liver steatosis, the binding results were comparable to those obtained in normal patients. Cirrhosis and metastasis patients showed a decreased binding towards Con A, while the binding against the various galactose- and fucose-recognizing lectins was increased. After neuraminidase treatment, an increased affinity towards all lectins was observed. However, differences in RCA I and RCA II binding between patients and controls still persisted. Besides sialic acid, also galactose and fucose residues contribute to serum gamma-glutamyltransferase heterogeneity.

Characterization of sialyltransferases from serum of normal and hepatoma Mc-29 bearing chickens

Sialyltransferase was measured in serum of normal and hepatoma Mc-29 bearing chickens. By preparative isoelectric focusing the multiple forms of sialyltransferase from both kind of serums was studied as well. By using influenza virus neuraminidase an attempt was made for partial structural characterization of the sialylation sites in asialofetuin applied as exogenous acceptor for sialyltransferase determination. It was established an elevated serum sialyltransferase activity in tumor bearing chickens with tumor an enzyme form was detected with pI-4.99 identical with an enzyme form described previously in solubilized plasma membrane preparations from hepatoma Mc-29. Monitoring of multiple forms of serum glycosyltransferases may be of value in answering the problem concerning the tissue origin of serum enzymes.

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

A synthetic substrate, N-acetyl-2'-O-methyllactosamine, was employed as a specific acceptor for alpha-L-(1----3)-fucosyltransferase from human serum. The fucosyl linkage of the product from this substrate was characterized by hydrolysis with a specific alpha-L-(1----3)/(1----4)-fucosidase. Using this acceptor, the pH optimum for the serum alpha-L-(1----3)-fucosyltransferase was 6.5. The enzyme was activated by Mn2+ or Mg2+ ions and was inhibited by EDTA. The apparent Km for this enzyme using N-acetyl-2'-O-methyllactosamine was 20.4 mM and Vmax was 5.6 pmol/h/ml serum.

Relation between raised concentrations of fucose, sialic acid, and acute phase proteins in serum from patients with cancer: choosing suitable serum glycoprotein markers

Serum concentrations of fucose, sialic acid, and eight acute phase proteins were measured in single specimens from patients with cancer in order to determine whether the raised concentrations of protein bound sugars commonly found in cancer correlate with increased concentrations of the acute phase proteins. Strong positive correlations were found only with alpha 1-acid glycoprotein, alpha 1-antitrypsin, and haptoglobins. Changes in protein bound sugars and acute phase proteins were also examined in relation to patients' disease states. Serum fucose was raised more often in patients with advanced disease than in those in whom the spread of the tumour was more restricted; increased sialic acid concentrations, however, were found with a similar frequency in both these groups. Combined use of fucose and sialic acid values gave a high degree of marker positivity which could be only slightly improved on by including measurement of acute phase proteins. The combined use of serum fucose and sialic acid concentrations may have value in monitoring patients with cancer: the sialic acid provides an index of the acute phase response and the fucose a measure of the tumour spread.

Evaluation of serum fucosyltransferases in malignancy

Incorporation of [14C]-fucose into the endogenous acceptor of serum and into the exogenous acceptors desialofetuin (alpha 2-fucosyltransferase) and desialodegalactofetuin (alpha 3-fucosyltransferase) was determined in controls and in patients with various malignant diseases. Seventy-five percent of untreated cancer patients showed increased incorporation rates into the endogenous acceptor of serum. Increased rates of alpha 2-fucosyltransferase activity were observed in 67% and of alpha 3-fucosyltransferase activity in 49% of patients respectively. After successful chemotherapy a fall of fucosyltransferase activities could be observed and in non-responding patients an increase of fucosyltransferase activities during and after therapy was found. Determination of fucosyltransferase activities might provide an additional biological marker in monitoring cancer patients.

Dolichol-bound oligosaccharides and the transfer of distal monosaccharides in the synthesis of glycoproteins by normal and tumor mammary epithelial cells

The main dolichol diphosphate-bound oligosaccharides present in primary cultures of both normal and tumor mouse mammary epithelial cells had the same size, yielded the same pattern after acetolysis and paper chromatography, had the same number of mannose residues susceptible to alpha-mannosidase degradation, and were composed of the same monosaccharide residues. This is the first demonstration that normal and tumor mammary cells have dolichol diphosphate-bound oligosaccharides with very similar, if not identical, structures. These compounds are intermediates in the synthesis of asparagine-linked oligosaccharides. On the other hand, normal and tumor cells showed differences in the specific activities of the enzymes involved in the transfer of the distal monosaccharides from the sugar nucleotides to glycoproteins. Sialyl- and fucosyltransferases were elevated and galactosyl- and N-acetylglucosaminyltransferases were diminished in mammary tumor cells. The intact tumor cells showed an increased fucosylation of glycoproteins of the asparagine-linkage type.

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.

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.

The membrane glycoproteins of the malignant cell

Experiments are described and reviewed demonstrating that the bound carbohydrates of glycoproteins of many forms of malignant cells differ from their normal counterpart. The difference involves many oligosaccharide groups and is essentially quantitative. The characteristics of the difference are discussed. Despite the consistency of the finding its significance is unknown because the function of bound carbohydrates is largely unknown. Some properties of protein-bound carbohydrates that may be of special relevance to malignancy and other pathological processes are considered. The array of structures found in the cell is highly complex but seems to be similar in man, hamster, mouse, chick and fish. On the other hand, the biosynthesis of these structures can be influenced and altered by the environment and by drugs; the cell is tolerant of variation in its bound carbohydrate; microheterogeneity of the carbohydrates is probably the rule rather than the exception; experiments to test the function of bound carbohydrate show only small effects. A role for the bound carbohydrates in evolution is proposed that is consistent with these characteristics. It is also postulated that altered, bound carbohydrates of most glycoprotein does not endanger the life of the cell but may be responsible for involvement and change of many processes some of which permit the malignant cell to divide persistently and to prosper.

Elevated glycosyltransferase activities in infected or traumatized hosts: nonspecific response to inflammation

Streptococcus pneumoniae infection leads to multifold increases in sialyltransferase, galactosyltransferase, alpha 2-fucosyltransferase, and alpha 3-fucosyltransferase activity of rat liver. Such changes may reflect an increased demand for glycosylation of acute-phase proteins synthesized and secreted by the liver during inflammatory processes. Serum sialyltransferase became elevated in bacteria-infected or burned rats and sandfly fever-infected humans, but did not correlate with acute-phase serum protein changes. These data suggest that nonparenchymal liver cells, such as macrophages, may contribute substantially to elevated sialyltransferase activity in the circulation during infection and, as such, represent a general host response to infection and tissue trauma.

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.

Determination of serum galactosyltransferase levels in ovarian cancer patients for the evaluation of the effectiveness of therapeutic programs

The activity of galactosyltransferase using endogenous acceptor(s), (GT-En) in the sera of ovarian cancer patients was significantly higher than age and blood-group matched controls. GT-En, and galactosyltransferase activity using an exogenous acceptor (GT-Ex), were assayed in the sera of 30 patients undergoing treatment for ovarian epithelial cancer, at the start of chemotherapy, and after a suitable interval. The direction of the alterations in levels of both these enzymes correctly reflected the clinical response to chemotherapy in most of these patients. The assay of GT-En and GT-Ex in the serum may be useful for the evaluation of the effectiveness of therapeutic programs in these patients.

Effect of partial hepatectomy and hydrocortisone administration on liver and serum sialyltransferase activities

Partial hepatectomy of rats was followed by a rise in liver sialyltransferase activity. The maximum (2.5-fold increase) was reached on the third day after the operation, after which the level started to decline, returning to normal by day 6. Determination of serum sialyltransferase in these animals showed a parallel pattern. Daily injection of 5 mg hydrocortisone to adrenalectomized rats led to a maximal 3-fold elevation in liver sialyltransferase within 3 days, but failed to elicit any change in the corresponding enzyme in the serum. Results from these two experiments suggest that the elevations of sialyltransferase in the tissue and in the circulation are independently regulated.

Sialyl transferase activity: a serum enzyme marker in the follow-up of cancer patients

Clinical evaluation of serum sialyl transferase as a diagnostic tool in malignant disease has shown that there is a strong correlation between enzyme activity and extent of tumor tissue. Thus, patients with large tumor masses show higher enzyme activity than patients with small tumors or in remission. Furthermore, the surgical removal of tumor tissue results in a decrease of enzyme activity to the normal range. The values remain low until metastases recur; this is connected with a new increase in enzyme activity. It has also been shown that successful chemotherapy corresponding to tumor reduction is reflected in lower values. We are thus led to believe that sialyl transferase is a relevant diagnostic blood parameter in the follow-up of cancer patients.

Correlation of UDP-galactose glycoprotein:galactosyltransferase levels in the sera with the clinical status of ovarian cancer patients

Uridine diphosphate-galactose : glycoprotein galactosyltransferase (EC 2.4.1.22) was measured serially prior to and after surgery in 4 patients with ovarian epithelial cancer. The levels of this enzyme in the sera correlated well with the clinical status of the patients. In 2 other patients, the follow-up was designed to detect recurrence, and the enzyme assay was started when the patients were clinically disease free. Elevation of galactosyltransferase preceded the clinical appearance of disease by 3-7 months. Serial determination of glycoprotein galactosyltransferase in serum may be useful for evaluating the effectiveness of therapeutic programs.

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.