Lewis blood group antigens defined by monoclonal anti-colon carcinoma antibodies

Tumor-Associated Glycans as Targets for Immunotherapy: The Wistar Institute Experience/Legacy

Tumor cells are characterized by the expression of tumor-specific carbohydrate structures that differ from their normal counterparts. Carbohydrates on tumor cells have phenotypical as well as functional implications, impacting the tumor progression process, from malignant transformation to metastasis formation. Importantly, carbohydrates are structures that play a role in receptor-ligand interaction and elicit the activity of growth factor receptors, integrins, lectins, and other type 1 transmembrane proteins. They have been recognized as biomarkers for cancer diagnosis, and evidence demonstrating their relevance as targets for anticancer therapeutic strategies, including immunotherapy, continues to accumulate. Different approaches targeting carbohydrates include monoclonal antibodies (mAbs), antibody (Ab)-drug conjugates, vaccines, and adhesion antagonists. Development of bispecific antibodies and chimeric antigen receptor (CAR)-modified T cells against tumor-associated carbohydrate antigens (TACAs) as promising cancer immunotherapeutic agents is rapidly evolving. As reviewed here, there are several cancer-associated glycan features that can be leveraged to design rational drug or immune system targets, applying multiple TACA structural and functional features to be targeted as the standard treatment paradigm. Many of the underlying targets were defined by researchers at the Wistar Institute in Philadelphia, Pennsylvania, which provide basis for different immunotherapy approaches.

Unexpected distribution of CA19.9 and other type 1 chain Lewis antigens in normal and cancer tissues of colon and pancreas: Importance of the detection method and role of glycosyltransferase regulation

BACKGROUND

CA19.9 antigen has been assumed as an abundant product of cancer cells, due to the reactivity found by immunohistochemical staining of cancer tissues with anti-CA19.9 antibody.

METHODS

Expression and biosynthesis of type 1 chain Lewis antigens in the colon and the pancreas were studied by immunodetection in tissue sections and lysates, quantification of glycosyltransferase transcripts, bisulfite sequencing, and chromatin immunoprecipitation assays.

RESULTS

CA19.9 was poorly detectable in normal colon mucosa and almost undetectable in colon cancer, while it was easily detected in the pancreatic ducts, together with Lewis b antigen, under both normal and cancer conditions. B3GALT5 transcripts were down-regulated in colon cancer, while they remained expressed in pancreatic cancer. Even ST3GAL3 transcript appeared well expressed in the pancreas but poorly in the colon, irrespective of normal or cancer conditions. CpG islands flanking B3GALT5 native promoter presented an extremely low degree of methylation in pancreatic cancer with respect to colon cancer. In a DNA region about 1kb away from the B3GALT5 retroviral promoter, a stretch of CG dinucleotides presented a methylation pattern potentially associated with transcription. Such a DNA region and the transcription factor binding site provided overlapping results by chromatin immunoprecipitation assays, corroborating the hypothesis.

CONCLUSIONS

CA19.9 appears as a physiological product whose synthesis strongly depends on the tissue specific and epigenetically-regulated expression of B3GALT5 and ST3GAL3.

GENERAL SIGNIFICANCE

CA19.9 and other Lewis antigens acquire tumor marker properties in the pancreas due to mechanisms giving rise to reabsorption into vessels and elevation in circulating levels.

SA-Lea and tumor metastasis: the old prediction and recent findings

Several in vivo studies demonstrated that tumor metastasis depend on the expression of carbohydrate Lewis structures. Lewis antigens and their derivatives such as Lewis b (Leb), Lewis X (LeX), sialyl Lewis X (SA-LeX), sialyl Lewis a (SA-Lea), and Lewis Y (LeY) were identified as tumor-associated structures approximately 20 years ago by Koprowski et al. using hybridoma technology and showed that upregulation and/or de novo expression of these determinants on the tumor cell surface is associated with a poor prognosis. LeX and SA-LeX are ligands for selectin adhesion molecules; E- and P-selectins are vascular receptors expressed on activated endothelial cells (ECs) and L-selectin is expressed on leukocytes. Leukocytes also express on their surface LeX and SA-LeX determinants, which are involved in the initial steps of extravasation, that is, rolling, which is alpha step mediated by interaction with E-selectin on ECs. We hypothesized that the tumor cells transmigration from the bloodstream to metastatic sites is similar to lymphocyte extravasation and that adhesion of cancer cells in analogy with the lymphocyte rolling is mediated by interaction of carbohydrate determinants on tumor cells with selectins on ECs. To assess the role of interaction of carbohydrate structures with E-selectin in metastatic process in vivo, we demonstrated that the peptides mimicking SA-Lea blocked colonization of tumor cells in experimental model of lung metastasis in vivo. Furthermore, the metastases formation was completely attenuated in E-selectin-knock out (KO) mice demonstrating the importance of selectin-mediated interaction in this process. We also showed that a peptide mimicking SA-Lea E-selectin ligand has an ability to significantly reduce neutrophil recruitment into peritoneal cavity in acute inflammatory conditions. These studies support the hypothesis that the interaction of tumor cells via the carbohydrate SA-Lea determinant and E-selectin constitutes the important step in the metastatic process in analogy with lymphocyte extravasation and that carbohydrate antigen mimics have a potential as anti-inflammatories and anti-adhesive tumor therapeutics.

Synaptic proteins in rat taste bud cells: appearance in the Golgi apparatus and relationship to alpha-gustducin and the Lewis(b) and A antigens

Taste receptor cells are continuously replaced during the life of the animal, but many of their sensory axons respond primarily to stimuli belonging to a single taste quality. This suggests that a newly arising taste cell must form a synapse with an appropriate sensory axon, requiring cell recognition that is likely to be mediated by surface markers. As an approach to studying this process, we attempted to locate synapses by immunolabeling taste buds of rats for proteins involved in neurotransmitter release. In taste bud cells of vallate papillae and nasoincisor ducts, double-labeling experiments showed that syntaxin-1, SNAP-25, synaptobrevin, and synaptophysin colocalized with the Golgi marker beta COP in elongated cytoplasmic compartments that extended from the perinuclear region into apical and basal processes of the cells. Labeled cells were spindle-shaped, identifying them as light cells. Syntaxin-1 appeared only in taste cells, but SNAP-25, synaptobrevin, and synaptophysin were also seen in nerve fibers. The synaptic vesicle glycoprotein SV2 appeared only in nerve fibers. Taste cells of fungiform papillae did not show immunoreactivity for presynaptic proteins or Golgi markers, but axonal labeling was similar to that in other regions. Taste cells with alpha-gustducin could express either presynaptic proteins or the carbohydrate blood group antigen Lewis(b), but not both. Therefore, Lewis(b) and presynaptic proteins are not expressed during the same period in the life of a taste bud cell. Most taste cells expressing syntaxin-1 (82%) also expressed the A blood group antigen, whether or not they expressed alpha-gustducin.

Differential expression of carbohydrate blood-group antigens on rat taste-bud cells: relation to the functional marker alpha-gustducin

An afferent nerve fiber supplying a taste bud receives input from several taste receptor cells, yet is predominantly responsive to one of the classic taste qualities (salt, acid, sweet, or bitter). This specificity requires recognition between taste receptor cells and nerve fibers that may be mediated by surface markers correlating with function. In an effort to identify potential markers, we used immunofluorescence and confocal microscopy to examine expression of the oligosaccharide blood-group antigens Lewis(b), A, and H type 2 in taste buds of the rat oral cavity. We compared the distributions of these antigens with that of alpha-gustducin, a G-protein subunit implicated in responses to sweet- and bitter-tasting substances. The A and Lewis(b) antigens were present only on spindle-shaped cells whose apical processes reached the taste pore. These antigens were not present on epithelial cells surrounding taste buds, and Lewis(b) was not found elsewhere in the digestive tract. Lewis(b) and A were not removed by lipid extraction, suggesting that they are present on glycoproteins rather than glycolipids. All Lewis(b)-positive cells expressed alpha-gustducin, but only a fraction of alpha-gustducin-positive cells expressed Lewis(b). The fraction of taste-bud cells expressing Lewis(b) decreased in the order: vallate papillae > foliate papillae > nasoincisor duct. The epiglottis had almost no taste-bud cells that expressed Lewis(b). The A antigen appeared on taste-bud cells that also expressed alpha-gustducin in the order: foliate and vallate papillae > nasoincisor duct and epiglottis > fungiform papillae. In addition, the A antigen was present on many cells that lacked alpha-gustducin in foliate and vallate papillae. In vallate papillae, cells expressed either A or Lewis(b), but not both. Lewis(b) appears to be restricted to differentiated light cells that also express alpha-gustducin and may be involved in intercellular interactions of these cells.

Light and dark cells of rat vallate taste buds are morphologically distinct cell types

Cells of mammalian taste buds have been classified into morphological types based on ultrastructural criteria, but investigators have disagreed as to whether these are distinct cell types or the extremes of a continuum. To address this issue, we examined taste buds from rat vallate papillae that had been sectioned transversely, rather than longitudinally, to their longest axis. In these transverse sections, dark (Type I) and light (Type II) cells were easily distinguished by their relative electron density, shape and topological relationships. Cells with electron-lucent cytoplasm (light cells) were circular or oval in outline, while those with electron-dense cytoplasm (dark cells) had an irregular outline with sheetlike cytoplasmic projections that separated adjacent light cells. A hierarchical cluster analysis of 314 cells across five morphological parameters (cell shape and area, and nuclear ellipticity, electron density and invagination) revealed two distinct groups of cells, which largely corresponded to the dark and light cells identified visually. These cells were not continuously distributed within a principal components factor solution. Differences in the means for dark and light cells were highly significant for each morphological parameter, but within either cell type, changes in one parameter correlated little with changes in any other. These analyses all failed to reveal cells with a consistent set of intermediate characteristics, suggesting that dark and light cells of rat vallate taste buds are distinct cell types rather than extremes of a continuum. Sections of taste buds were stained with antibodies to several carbohydrates, then observed by indirect immunofluorescence. Optical sections taken with a confocal laser-scanning microscope showed that the Lewis antigen was present only on spindle-shaped cells with circular or oval outlines and lacking transverse projections; these characteristic shapes matched those of light cells seen by electron microscopy. The H blood group antigen and the 2B8 epitope appeared at most cell-cell interfaces in the bud and are present on dark cells and possibly on some light cells. These findings relate molecular markers to morphological phenotypes and should facilitate future studies of taste cell turnover, development and regeneration.

Human alpha(1,3/1,4)-fucosyltransferases discriminate between different oligosaccharide acceptor substrates through a discrete peptide fragment

Five different human alpha(1,3)-fucosyltransferase (alpha(1,3)-Fuc-T) genes have been cloned. Their corresponding enzymes catalyze the formation of various alpha(1,3)- and alpha(1,4)-fucosylated cell surface oligosaccharides, including several that mediate leukocyte-endothelial cell adhesion during inflammation. Inhibitors of such enzymes are predicted to operate as anti-inflammatory agents; in principle, the isolation or design of such agents may be facilitated by identifying peptide segment(s) within these enzymes that interact with their oligosaccharide acceptor substrates. Little is known, however, about the structural features of alpha(1,3)-Fuc-Ts that dictate acceptor substrate specificity. To begin to address this problem, we have created and functionally characterized a series of 21 recombinant alpha(1,3)-Fuc-T chimeras derived from three human alpha(1,3)-Fuc-Ts (Fuc-TIII, Fuc-TV, and Fuc-TVI) that maintain shared and distinct polypeptide domains and that exhibit common as well as idiosyncratic acceptor substrate specificities. The in vivo acceptor substrate specificities of these alpha(1,3)-Fuc-T chimeras, and of their wild type progenitors, were determined by characterizing the cell surface glycosylation phenotype determined by these enzymes, after expressing them in a mammalian cell line informative for the synthesis of four distinct alpha(1,3)- and alpha(1,4)-fucosylated cell surface oligosaccharides (Lewis x, sialyl Lewis x, Lewis a, and sialyl Lewis a). Our results indicate that as few as 11 nonidentical amino acids, found within a "hypervariable" peptide segment positioned at the NH2 terminus of the enzymes' sequence-constant COOH-terminal domains, determines whether or not these alpha(1,3)-Fuc-T can utilize type I acceptor substrates to form Lewis a and sialyl Lewis a moieties.

Elevated expression of H type GDP-L-fucose:beta-D-galactoside alpha-2-L-fucosyltransferase is associated with human colon adenocarcinoma progression

GDP-L-fucose:beta-D-galactoside alpha-2-L-fucosyltransferase (EC 2.4.1.69) is a key enzyme in the biosynthesis of fucosylated type 1 and 2 lactoseries structures, such as Lewis b and the H type 2 and Lewis Y, respectively, that are accumulated in colon adenocarcinoma. Analysis of the mRNA transcript level for the human H gene-encoded beta-D-galactoside alpha-2-L-fucosyltransferase revealed 40- and 340-fold increases in the mRNA levels in all adenocarcinomas and tumor cell lines, respectively, compared to normal colon mucosa where a low level of mRNA transcript was detected. A variable increase in mRNA transcript levels was observed in 50% of adenomatous polyps. Nucleotide sequence analysis of the protein coding region of the cDNAs derived from normal colon, adenoma, and colon adenocarcinoma revealed 100% homology, suggesting that there are no tumor-associated allelic variations within the H beta-D-galactoside alpha-2-L-fucosyltransferase cDNA. These results suggest that beta-D-galactoside alpha-2-L-fucosyltransferase expression highly correlates with malignant progression of colon adenocarcinoma.

Taste bud expression of human blood group antigens

Some human blood group antigens are expressed by rodent epithelial cells at different stages of differentiation. Since adult taste cells are continually replaced throughout life, we investigated the expression of the H, B, A and Lewisb blood group determinants by cells of the rat fungiform, foliate and vallate papillae. We employed antibodies against the trisaccharide structures of the H, B, and A blood group antigens and against the Lewisb blood group epitope in studies of normal and denervated taste buds. The antibody against the H antigen reacted with the majority of cells in all taste buds and with cells in the spinous layer of the tongue epithelium. The B antigen was expressed by the majority of taste cells but not by other epithelial cells. The expression of the A antigen was significantly less in the fungiform taste buds than in the vallate or foliate taste buds. The A antigen was also abundantly expressed in the acini of the lingual salivary glands. The Lewisb epitope was expressed by a subset of cells in taste buds of the fungiform, foliate and vallate papillae. Taste buds are trophically dependent upon gustatory nerve innervation. Transection of the chorda tympani or the IXth nerve resulted in the loss of expression of these molecules from the gustatory epithelium, indicating that they are expressed only on differentiated taste cells. The blood group antigens are lactoseries carbohydrates; they are differentially expressed in developing cochlear hair cells and olfactory neurons and may play roles in cell-cell recognition, adhesion, and other interactions important in the developing nervous system. They could have similar functions in the taste and olfactory systems, where the receptors are continually renewed and new synapses between the receptors and their neural targets continually form.

Differences in antigen expression between neoplastic and nonneoplastic gallbladder epithelium. An immunohistochemical study

Immunoreactivity for a panel of 15 monoclonal antibodies (MAbs), which are known to react with different gastrointestinal tumor antigens, was assessed in formalin-fixed paraffin-embedded sections that were prepared from cholecystectomy specimens obtained from Mexican patients. Each case was classified histologically into one of the following groups: (1) invasive adenocarcinoma (N = 21), (2) high-grade dysplasia (carcinoma in situ) (N = 2), (3) low-grade dysplasia (N = 4), hyperplasia (4) (N = 15), and (5) chronic cholecystitis (N = 10). Significant differences (P < 0.05) were identified among the five histopathologic groups in the proportion of epithelial cells demonstrating immunoreactivity with MAbs to Lewisb; Lewis(a); sialylated Lewis(a); sialylated Lewis(a) and Lewis(a); Y antigen; H antigen; X antigen; X-like antigen; 200-kDa protein of CEA; 180-, 160-, 50-, 40-kDa proteins of CEA; 30- to 37-kDa protein; and an undefined antigen identified by MAb 99-57, with invasive carcinoma more frequently being positive as compared to nonneoplastic (hyperplasia, chronic cholecystitis) epithelium. Significant differences were also observed among the five histopathologic groups (P < or = 0.0005) in the proportion of epithelial cells demonstrating immunoreactivity with MAbs to Y antigen and the 20- to 50-kDa glycoprotein. However, with these two antibodies immunoreactivity was more frequently found in nonneoplastic epithelium rather than in invasive carcinomas. No significant differences in immunoreactivity were detected among the different histologic groups with MAb to blood group B antigen, types 1 and 2. This study demonstrates that cellular antigens are both developed and lost during the process of neoplastic transformation in the gallbladder.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycolipids carrying Le(y) are preferentially expressed on small-cell lung cancer cells as detected by the monoclonal antibody MLuC1

The monoclonal antibody MLuC1, which reacts strongly with a high percentage of small-cell lung cancers (SCLC), as well as with various human carcinomas, has been used to immunochemically characterize the recognized epitope (CaMLuC1). To this aim 3 different approaches were adopted: (1) immunoblotting/immunostaining of extracts from various tumor-cell lines; (2) inhibition of binding by purified oligosaccharides; (3) direct binding to oligosaccharide-protein conjugates. All of these experiments indicate that CaMLuC1 is present on the Le(y) blood-group structure heterogeneously expressed on various glycoproteins and glycolipids. The expression of the glycoconjugates carrying Le(y) was then analyzed on breast and lung cancers and on their normal counterparts. Our overall results suggest that SCLC produce Le(y)-active glycolipids in higher amounts compared to other tumors of the same or of a different oncotype, as well as normal lung cells, thus indicating an SCLC-specific modification of the glycosylation pathways.

Isolation and characterization of a monoclonal antibody, K1, reactive with ovarian cancers and normal mesothelium

We have isolated a new monoclonal antibody (MAb), K1, that reacts with an epitope on the surface of human ovarian carcinoma cells. This antibody was generated by immunization of mice with periodate-treated human ovarian carcinoma (OVCAR-3) cells. These mice had been previously made tolerant with normal human kidney membranes. Spleen lymphocytes from these mice were selected prior to fusion using a panning purification method on living OVCAR-3 cells. Initial screening of surface-reactive clones was performed in a single day using immunofluorescence on living OVCAR-3 cells, and secondary screening was performed using immunoperoxidase histochemistry on cryostat sections of normal human tissues and human tumors. The K1 clone was subcloned and identified as an IgM isotype, but was subsequently isotype-switched to IgG1K using a panning selection method. When evaluated by immunohistochemistry, the antigen reactive with K1 was found in many ovarian non-mucinous tumors, as well as in squamous tumors of the esophagus, and cervical cancer. The only normal adult human tissues showing uniform reactivity with K1 were the mesothelia of the peritoneal, pleural and pericardial cavities. There was also limited reactivity with epithelia of the trachea, tonsil and Fallopian tube. A similar tissue reactivity for K1 was found in tissues from cynomolgus monkeys. K1 reacted with many of the same tissues and tumors as the previously identified antibody OC125, but several lines of evidence indicate that K1 reacts with a different epitope and probably a different molecule, when compared to OC125. This evidence included assays employing immunofluorescence competition, double-label immunofluorescence, and solid-phase and live-cell radioimmunoassays. Since our data indicate that the antigen reactive with the K1 antibody is a new molecular species, we have named the antigen CAK1. Unlike the shed antigen CA125, CAK1 was only cell-associated and was not found in the supernatant of cultured OVCAR-3 cells or in the blood of ovarian cancer patients. The K1 antibody may be useful as a targeting agent for therapy and in the diagnosis of ovarian carcinoma, as well as some other human cancers.

Quantitative dot blot analyses of blood-group-related antigens in paired normal and malignant human breast tissues

Membranes were prepared from 31 breast-cancer specimens and adjacent mammary tissues, dot-blotted to nitrocellulose paper, and reacted with monoclonal antibodies (MAbs) (A, B, Lewis a, Lewis b, sialylated Lewis a, Lewis x, and Lewis y) and lectins (Ulex europaeus, peanut agglutinin) having various blood-group specificities. The expression of epithelial membrane antigen was assayed with MAb MA5. The ratio of breast-cancer to normal mammary membrane preparations (C/N ratios) of these reagents was measured by densitometric scanning. We observed a decrease in the levels of A, B, Lewis a, Lewis b, sialylated Lewis a, and Lewis y antigens and an increase of Lewis x, T, and MA5-reactive determinants in breast cancers. The incidence of incompatible A, as well as A and B, antigens was demonstrated for 2 patients of blood group B and O respectively. When the receptor content was plotted against the C/N ratio of these various reagents, a significant inverse relationship between the C/N ratio of Lewis x antigen and estrogen (ER) and progesterone receptor (PR) content was observed in breast cancers. The mean C/N ratio of Lewis x antigen was significantly higher in the ER-negative/PR-negative (ER-/PR-; 2.33 +/- 1.17), as compared with the ER-positive/PR-positive (ER+/PR+; 0.97 +/- 0.80). According to these observations, Lewis x antigen expression may be influenced by hormonal stimuli such as estrogen and progesterone.

Cancer-associated carbohydrates identified by monoclonal antibodies

"New" carbohydrate structures on the surface of or secreted by cancer cells, identified as epitopes by monoclonal antibodies, are reviewed. These structures may represent the accumulation of precursor chains because of decreased activity of synthesizing enzymes, the production of new oligosaccharides due to increased or aberrant glycosylation of carbohydrate chains, a change in density of carbohydrates on the cell surface, or exposure of chains usually covered by other structures. Alterations in glycolipid synthesis include aberrant fucosylation and/or sialyation of the lacto series, sialylation or fucosylation of the globo series, and sialyation of the ganglio series. Many of these carbohydrate epitopes have become useful for the diagnosis, prognosis, and monitoring of patients with cancer. Some of the important markers include CA 15.3, CA 19.9, CA 50, CA 125, CA 242, MCA, SLEX, etc. Incomplete glycosylation of O-linked mucin oligosaccharide is recognized as the important "cancer antigen" B72.3, which is sialyated Tn. The oligosaccharide components of alpha-fetoprotein, carcinoembryonic antigen, and epidermal growth factor receptor are also reviewed. In many instances the glycosylation seen in cancer cells or their products reflects patterns seen during normal development. Thus, cancer-associated oligosaccharides are oncodevelopmental in nature. The biologic significance of carbohydrates on cell surfaces is not known, but several possibilities include a role in cell to cell recognition, intracellular processing of glycoproteins, cell activation, and ability of cancer cells to metastasize.

Comparative studies on the expression of gastrointestinal-cancer-associated antigen, PA8-15, CA19-9 and the blood-group antigens in non-malignant and malignant human pancreatic tissues

The expression of PA8-15 antigen and the blood-group-related antigens A, B, O, Le(a), Le(b), Le(x), and Le(y), as well as CA19-9, were examined in the normal pancreas and in specimens from benign and malignant pancreatic tissue by the avidin-biotin-immunoperoxidase technique. A correlation was found between the expression of PA8-15, Le(a), and CA19-9 in some cases. However, in the cancer tissues in which neither Le(a) nor CA19-9 could be demonstrated, strong expression of PA8-15 was observed. The reactivity of monoclonal antibody (mAb) PA8-15 with pancreatic cancer tissue was not inhibited by the preincubation of the sections with the mAb anti-Le(a) (CO514) and mAb CA19-9 (CO19-9) indicating that the epitope recognized by PA8-15 is different from that detected by the other two antibodies. Moreover, unlike Le(a) and CA19-9, PA8-15 was also expressed in cancer cells of patients of the Le(a-b-) type. The results suggest that mAb PA8-15 recognizes a sialylated molecule related to Le(a) but different from CA19-9, and seems to be an additional useful marker for pancreatic cancer.

Detection of Lewisaantigen in sera of ovarian carcinoma patients by MOv2-MOv8 double-determinant radioimmunoassay

The monoclonal antibodies MOv2 and MOv8, raised against ovarian carcinoma, were found to be directed against two non-crossreacting epitopes expressed on the same molecule. Immunochemical analysis of the MOv8 recognized epitope showed that the Leaoligosaccharide, or commercial anti-LeaMAb, but not the anti-LebMAb, prevented MOv8 binding to the reference target cell line (SW626), indicating that it is carried by the Leaantigen. Since we previously reported that MOv2 also recognises the Leaantigen, these data suggest that Mov8 and Mov2 were directed against different epitopes on the same oligosaccharide chain. Bearing in mind the knowledge of the biochemical nature of the monoclonal antibody recognized epitopes (CaMOv2 and CaMOv8), the presence of the circulating molecules recognized by them was analyzed by double determinant immunoradiometric assay (DDIRMA) in 103 sera from ovarian carcinoma patients. Patients with clinical evidence of the disease (ED) with MOv2 and MOv8 reactive and negative tumors had sera reactivity in 67% and 19% respectively. Also, 26% of the patients with no clinical evidence of disease (NED) had positive sera. When we investigated the relationship between MOv2-MOv8 DDIRMA sera positivity and red blood cells (RBC) Lewis phenotype, a strong correlation was found between the Lea+phenotype and DDIRMA sera reactivity in healthy donors (6/6) and in ovarian carcinoma patients (9/10) whatever their clinical condition. No Leahealthy donors gave evidence of MOv2-MOv8 reactive sera. In contrast, 33% and 57% of the sera from ED carcinoma patients with respectively Leab+and Leabphenotype were positive.

In conclusion, the percentage of DDIRMA positive cases previously reported in healthy donors and found here in ovarian carcinoma patients with MOv2 and MOv8 negative tumors or NED, was in agreement with Lea +phenotype frequency in the normal Caucasian population. However the Lewisacould represent a tumor-associated antigen in ED patients with Leaphenotype and MOv2-MOv8 DDIRMA might be useful for monitoring the disease

The glycosphingolipid composition of the human hepatoma cell line,Hep-G2

The origin of plasma glycosphingolipids in normal individuals and the mechanisms by which tumor-associated glycosphingolipid antigens enter the plasma in patients with cancer are largely unknown. The Hep-G2 human hepatoma cell line retains many of the characteristics of differentiated hepatocytes including the ability to synthesize and secrete lipoproteins. Preliminary results indicated that newly synthesized Hep-G2 cell glycosphingolipids are coupled to the secreted lipoproteins. This suggests that this cell line may offer an interesting model for studying glycosphingolipid secretion, transfer, and shedding. We now report on the chemical and immunological characterization of Hep-G2 cell glycosphingolipids. Five major glycosphingolipids were purified and biochemically characterized: glycosylceramide, lactosyl ceramide, ceramide trihexoside, ganglioside GM3, and lactosyl sulfatide. Four additional minor components (3-fucosyl-lactosamine containing glycolipids, asialo GM2, galactosylgloboside, and ganglioside GM1) were identified using a combination of exoglycosidase digestion and immunostaining of thin-layer chromatography plates with specific carbohydrate binding proteins. This demonstrates that although this cell line synthesizes a limited number of major glycosphingolipids, it retains the ability to produce at least small amounts of structures in the lactoneo, globo, and ganglio series of glycosphingolipids. These studies show that it will be possible to investigate the mechanisms of secretion by Hep-G2 cells of different classes of these molecules such as neutral glycosphingolipids, gangliosides, and sulfatides.

Blood group antigens in the intrahepatic biliary tree. II. Type 1 chain N-acetyllactosamine-related carbohydrate antigens in the proliferated bile ductules

The expression of the carbohydrate antigens related to type 1 chain N-acetyllactosamine (1NAcLc) in the proliferated bile ductules was immunohistochemically examined in liver tissues of 10 cases of chronic hepatitis (CH), 9 of liver cirrhosis (LC) and 8 of alcoholic hepatitis. The ductular expression of the examined blood group antigens was essentially the same among these pathological conditions. The backbone structure, i.e., 1NAcLc (Gal beta 1----3GlcNAc beta 1----3Gal beta 1----3R), was not detected in the proliferated ductules as in the normal bile ductules. Its fucosylated structures (Le(a), Le(b) and type 1 chain H) were more strongly expressed in the proliferated ductules than in the normal ductules. Sialyl-Le(a) which was not found in the normal ductules was detected weakly but definitely in the proliferated ductules. Besides proliferated ductules, single or small numbers of epithelial cells expressing the 1NAcLc-related antigens were found intralobularly. This suggests possible migration of biliary epithelial cells into the hepatic lobules. In conclusion, within the proliferated bile ductules (a) synthesis of the 1NAcLc-related antigens is increased compared to the normal ductules, (b) the backbone structure is completely sialylated or fucosylated as in the normal ductules and (c) alpha 1----4fucosylation of sialyl-1NAcLc, i.e., sialyl-Lea, formation occurs despite its absence in the normal ductules.

Malignant cell glycoproteins and glycolipids

The cell surface is involved in cell growth and division, cell-cell interaction, communication, differentiation and migration, and other processes likely to be involved in malignant transformation and/or the metastatic spread of cancer. Although there are many alterations of glycoproteins and glycolipids on the malignant cell surface, it is unclear whether these alterations are epiphenomena or an integral part of the malignancy process. This article reviews the recent literature and some earlier studies relevant for understanding emerging concepts and trends with respect to malignant cell glycoconjugates. Emphasis is on structural alterations of the carbohydrate portions of malignant cell glycoproteins and glycolipids and on the enzymes (glycosyltransferases and glycosidases) involved in their metabolism. Practical applications derived from malignant cell glycoconjugate studies are discussed briefly with respect to the diagnosis, staging, monitoring, and treatment of malignant disease. The review concludes by indicating which research areas on malignant cell glycoconjugates are likely to be fruitful in increasing our basic understanding of, and ability to deal effectively with, malignant disease.

Glycolipids of human large intestine: difference in glycolipid expression related to anatomical localization, epithelial/non-epithelial tissue and the ABO, Le and Se phenotypes of the donors

Human large intestine specimens were obtained during elective surgery from donors of known blood group ABO, Lewis and secretor phenotypes. The intestinal epithelial cells were isolated from the non-epithelial tissue in one case and in another case mucosa tissue was obtained by scraping. Total non-acid glycolipid and ganglioside fractions were isolated from the tissue specimens, analyzed by thin-layer chromatography and detected by chemical reagents and autoradiography after staining the plate with various blood group monoclonal antibodies and bacterial toxins. The amount of non-acid glycolipids present in the large intestine epithelial cells was 3.9 micrograms/mg of cell protein and in the non-epithelial tissue 0.39 mg/g dry tissue weight. The epithelial cells contained monoglycosylceramides and blood group Lea pentaglycosylceramides as major compounds together with small amounts of diglycosylceramides. In addition, trace amounts of tri- and tetra-glycosylceramides together with more complex glycolipids were present. The non-epithelial tissue contained mono-, di-, tri- and tetra-glycosylceramides as major non-acid components. Blood group ABH glycolipids were present in trace amounts in the non-epithelial part of the large intestine. Lea pentaglycosylceramide was the major blood group glycolipid present in all Le-positive individuals independent of the secretor status. Leb glycolipids were present in trace amounts in secretor individuals but completely lacking in non-secretors. Trace amounts of X antigens were found in all individuals, while Y antigens were only present in secretor individuals. The Lea, Leb, X and Y glycolipids were located in the epithelial cells. The gangliosides were present mainly in the non-epithelial tissue (65-350 nmol of sialic acid/g dry weight) and only trace amounts (less than 0.014 nmol/mg of cell protein) were found in the epithelial cells. The major gangliosides of the non-epithelial tissue were identified as GM3, GM1, GD3, GD1b, GT1b and GQ1b. In addition, several minor gangliosides were also present. Binding of cholera toxin to the thin-layer plate revealed trace amounts of the GM1 ganglioside in the epithelial cell ganglioside fraction.

Immunohistochemical application of monoclonal antibodies to reveal the structure and localization of carbohydrate antigens. N-acetyllactosamine-related carbohydrate antigens in human biliary epithelial cells

With the use of a panel of monoclonal antibodies against structurally related carbohydrate antigens, finely regulated cellular phenotype of the carbohydrate antigens can be characterized. As a model system, the expression of N-acetyllactosamine-related antigens in human biliary epithelial cells was investigated using 16 murine monoclonal antibodies against different carbohydrate epitopes. Human biliary epithelial cells expressed type 1 backbone-related antigens at all synthetic stages. Type 2 backbone and its monofucosylated structures, i.e., Lex and H, were never detected. More complex type 2 chain antigens, i.e., Ley, A and ALey, were apparently expressed. Types 3 and 4 chain antigens were also shown to be expressed. However, the expression of N-acetyllactosamine-related antigen was polymorphic and differed from one individual to another. Furthermore, in spite of the topographical continuity of the biliary tree, biliary epithelial cells were not always equal in the expression of N-acetyllactosamine-related antigens. As a conclusion, not only the localization but also the structure of carbohydrate antigens can be immunohistochemically studied on the tissue sections with the use of well defined monoclonal antibodies.

Detection and isolation of oligosaccharides with Lea and Leb blood group activities by affinity chromatography using monoclonal antibodies

Affinity columns prepared by immobilizing monoclonal antibodies that specifically recognize the Lea or the Leb blood group antigens can be used for analytical or preparative isolation of oligosaccharides with the corresponding reactivities. The number of immobilized functional antibody combining sites on a column and the dissociation constants for standard oligosaccharides are determined by frontal analysis. By employing a simple approximation [K.-I. Kasai et al. (1986) J. Chromatogr. 376, 33-47] these parameters can be used to rationally design columns with properties appropriate for zonal affinity chromatography. The affinity for binding of the Lea-active oligosaccharide lacto-N-fucopentaose II (LNF II) by the anti-Lea antibody CO-514 doubles for each 8 degrees C downward shift in temperature between 37 and 4 degrees C. By zonal chromatography, Lea- or Leb-active oligosaccharides are recovered from a complex mixture of milk oligosaccharides containing more than a 20-fold molar excess of structurally similar but antigenically distinct oligosaccharides. The capacity for preparative isolation of an oligosaccharide increases in a linear fashion with the amount of antibody loaded on the solid support. The monoclonal antibodies used in these studies are products of hybridomas derived from mice immunized with human colorectal carcinoma cell lines [M. Blaszczyk et al. (1984) Arch. Biochem. Biophys. 233, 161-168]. The experiments establish that affinity chromatography applied to mixtures of oligosaccharides released by enzymatic or chemical cleavage of glycoconjugates may simplify the task of isolating and characterizing biologically interesting target antigens of monoclonal antibodies.

Biosynthetic pathways for the Leb and Y glycolipids in the gastric carcinoma cell line KATO III as analyzed by a novel assay

The biosynthetic pathways for the difucosylated type 1 and 2 glycolipids, Leb and Y, respectively, were investigated in the gastric carcinoma cell line KATO III, using a novel chromatogram binding assay. The type of fucosylation obtained was deduced from the binding pattern of monoclonal antibodies specific for the biosynthesized glycolipid products using microsomal fractions as the source of enzyme, pure glycolipids and non-radioactive GDP-fucose as acceptor and donor substrates, respectively. The Leb glycolipid (Fuc alpha 1----2Gal beta 1----3GlcNAc(4----1 alpha Fuc) beta 1----3LacCer) was synthesized mainly via the blood group H, type 1, precursor (Fuc alpha 1----2Gal beta 1----3GlcNAc beta 1----3LacCer). However, the Lea glycolipid (Gal beta 1----3GlcNAc(4----1 alpha Fuc)beta 1----3LacCer) also served as a precursor for the alpha 1----2 fucosyltransferase, thus allowing conversion of Lea to Leb. This biosynthetic route represents either an "aberrant" specificity of the Fuc alpha 1----2 transferase associated with these gastric carcinoma cells and/or a new member of the alpha 1----2 fucosyltransferase family. The Y glycolipid (Fuc alpha 1----2Gal beta 1----4GlcNAc(3----1 alpha Fuc)beta 1----3LacCer) was synthesized exclusively via the classical pathway using the blood group H type 2 glycolipid (Fuc alpha 1----2Gal beta 1----4GlcNAc beta 1----3LacCer) as precursor. The X glycolipid (Gal beta 1----4GlcNAc(3----1 alpha Fuc)beta 1----3LacCer) did not serve as an acceptor substrate for the alpha 1----2 fucosyltransferase(s) present. The use of non-radioactive sugar-nucleotides as donor substrate, defined glycolipid precursors as acceptor substrates and of specific monoclonal anti-glycolipid antibodies for detection provides a rapid and highly specific assay for analyzing biosynthetic pathways of glycosyltransferases.

Blood group antigens in the intrahepatic biliary tree. I. Distribution in the normal liver

The distribution of six blood group-related antigens, A, B, H, Lea, Leb and sialylated Lea antigens, in the intrahepatic biliary tree was studied. These carbohydrate antigens in fixed normal liver tissues were immunostained with the use of highly specific monoclonal antibodies in an avidin-biotin-peroxidase complex method. Bile ducts expressed both ABH and Lewis blood group antigens. However, only Lewis blood group antigens could be detected in the bile ductules. Canaliculo-ductular junctions could be clearly delineated with the anti-Lewis blood group antibodies, especially with anti-Lea antibody. Small Lewis antigen-positive cells were scattered intralobularly. They were adjacent to parenchymal liver cells, mainly in Rappaport zone 1, and apparently in continuity with the portal biliary tree. Sialylated Lea antigen was found in some septal bile ducts. No blood group antigen could be detected in the bile canaliculi. These results indicate that (1) biliary tract of a given size has its own pattern of blood group antigen expression, and (2) biliary epithelial cells are not identical with regard to the phenotypic expression of their structural carbohydrates. In future, it will be possible to classify biliary epithelial cells by their blood group antigen expression.

Tumorigenic human squamous lung cancer cells have defined cell surface carbohydrates that are absent from nontumorigenic cells

Cells of cloned lines derived from human squamous lung carcinomas spontaneously become heterogeneous with respect to several tumor-associated cell surface carbohydrates such as the sialosyl-Lea oligosaccharide antigen or the recently described oligosaccharide recognized by monoclonal antibody 43-9F. Subclones derived from these cultures are initially homogeneous with respect to the presence or absence of a specific cell surface carbohydrate but gradually revert back to a heterogeneous population. Cells of homogeneous subclones having both the sialosyl-LEa and 43-9F cell surface antigens and other subclones lacking them were injected subcutaneously in nude mice. All clones expressing these tumor-associated cell surface carbohydrates were found to be highly tumorigenic, whereas those lacking them were nontumorigenic or, at most, weakly tumorigenic. Clones having the tumor-associated cell surface carbohydrates were more resistant to cytotoxic attack by purified mouse natural killer cells than those clones lacking these carbohydrates, suggesting that the tumorigenicity of the former clones may be influenced by immunoprotective effects of these novel carbohydrates.

The chemical basis for expression of the sialyl-Le(a) antigen

The SLe(a) antigen, originally defined by monoclonal antibody 19-9, is a complex carbohydrate epitope that differs from the normal human blood group Lea antigen only by the presence of an additional sialic acid residue. SLe(a)-active oligosaccharides occur in both gangliosides and mucin-like glycoproteins in developing embryonic gut, as well as in many normal adult glandular tissues and secretions, but the antigen is virtually absent from normal adult gastrointestinal lumenal epithelial cells. Following malignant transformation of adult gastrointestinal lining epithelium and many other endodermally-derived glandular epithelia, SLe(a)-active mucins released from the ensuing tumor appear in blood plasma. The level of circulating SLe(a) antigen is currently being investigated as a means of following tumor recurrence, progression, and therapy. Recent studies on the biosynthesis of SLe(a) explain the observations that, 1) the antigen does not occur in individuals of Le(a-b-) blood group, and 2) individuals that belong to the Le(a+b-) blood group express SLe(a) more strongly than Le(a-b+) individuals. Further, the biosynthetic studies predict a new tumor antigen, NeuAc alpha 2-3Gal beta 1-3GlcNAc beta 1.... (the immediate precursor to SLe(a)) that should be expressed in Le(a-b-) individuals in nearly the same tissue distribution as found for the SLe(a) antigen in Le(a+b-) and Le(a-b+) individuals. Based upon studies of SLe(a) expression in normal saliva and the pathway for biosynthesis of SLe(a), it seems likely that future clinical studies could be profitably directed towards improving the predictive value of the plasma SLe(a) level by adjusting the quantitative results according to the Lewis blood group and ABH secretor phenotype of the individual patient.

A mucin containing the X, Y, and H type 2 carbohydrate determinants is shed by carcinoma cells

Monoclonal antibody BR 15-6A directed to the Y carbohydrate determinant (Fuc alpha 1----2Gal beta 1----4GlcNAc(3----1Fuc) beta 1----3Gal beta 1----4Glc beta 1----1Cer) reacted with the cell surface and conditioned media of colorectal and breast carcinoma cell lines. Double determinant immunoassays using BR 15-6A as detector antibody showed that the Y determinant is part of a high molecular weight mucin that coexpressed other carbohydrate antigens based on a type 2 chain (X, H type 2). Type 1 chain carbohydrates such as sialylated Lewisa, Lewisa and Lewisb blood group antigens were predominantly expressed on a separate mucin molecule as determined by double-determinant immunoassays with other anticarbohydrate monoclonal antibodies. The X, Y, and H type 2-bearing mucin was present in conditioned media of the majority of colorectal carcinoma cell lines and in all three breast cancer cell lines tested. Thus, monoclonal antibodies against X, Y, and H type 2 determinants are potentially useful in the serodiagnosis of gastrointestinal and breast cancer.

Expression of ABH and Lewis blood group antigens in combined hepatocellular-cholangiocarcinoma. Possible evidence for the hepatocellular origin of combined hepatocellular-cholangiocarcinoma

Expression of ABH, Lewis, and sialyl Lea antigens was studied in five combined hepatocellular-cholangiocarcinomas. Formalin-fixed liver tissues were immunostained for those antigens using well-characterized monoclonal antibodies and an avidin-biotin-peroxidase complex (ABC) method. Results were compared with those obtained in normal liver tissues and cholangiocarcinomas, and also with the previous observations of the authors on hepatocellular carcinomas. Although not detected in normal parenchymal liver cells, A, H, Lewis, and sialyl Lea antigens were found in combined hepatocellular-cholangiocarcinoma cells. Incompatible A antigen also was detected in one blood type O patient. Distribution and intensity of the antigens were similar to those in hepatocellular carcinomas and different from those in cholangiocarcinomas. No preferential accumulation of blood-group antigens could be found in the area of cholangiocarcinoma-like differentiation of the combined hepatocellular-cholangiocarcinoma. The observations suggested that Regional morphological differentiation of the hepatocellular-cholangiocarcinoma might not be always associated with the change in the expression of the blood group antigens. Moreover, the expression was essentially the same between the hepatocellular-cholangiocarcinoma and the typical hepatocellular carcinoma. The hepatocellular-cholangiocarcinoma, therefore could be a variant of the hepatocellular carcinoma.

Fecal excretion of intestinal glycosphingolipids by newborns and young children

Glycosphingolipids were shown to persist in human fecal excretions from birth up 2 years of age. The pattern of glycosphingolipids was dependent on blood group and secretor status of the child and changed dramatically during the first months of life. Perinatally cerebroside, hematoside and blood group active fucolipids were dominating among fecal glycolipids. From the time of weaning lactosylceramide abruptly became and then persisted as a dominating glycolipid although cerebroside, complex gangliosides and blood group active fucolipids could still be detected in feces even at 2 years of age.

Lewis and related tumor-associated determinants on ovarian carcinoma

Monoclonal antibodies that defined blood group and related determinants bind to sections of fixed tissues from epithelial ovarian carcinoma in immunoperoxidase assays. Seventy-eight carcinomas and 27 normal tube and ovarian tissues were examined. Lewis (Le)a and Leb determinants were expressed on 58% of the serous carcinomas, on 60% of the endometrioid tumors, and on 78% of the mucinous carcinomas. Sialylated Lea, gastrointestinal cancer-associated antigen (GICA), and lacto-N-fucopentaose (LNF) III, another Le-related determinant, have a similar distribution pattern. Of 10 normal ovaries and fallopian tubes tested from patients without cancer, one reacted with anti-Lea, anti-Leb, or anti-LNF III monoclonal antibodies. Anti-GICA antibodies reacted with tissue from one patient. Le and Le-related antigenic determinants could be useful markers for ovarian cancer.

Carbohydrate sequences detected by murine monoclonal antibodies

The carbohydrate sequences of cell surface glycolipids change during differentiation and oncogenic transformation. To detect these structural changes, murine monoclonal antibodies have been produced in many different laboratories. Some of these antibodies are used to distinguish various cell types such as normal and transformed cells, while others are used to analyze developmentally regulated antigens. Recently, the structures of many of these carbohydrate antigens have been determined. The availability of these well-defined monoclonal antibodies will be useful for the study of the regulation and function of glycoconjugates.

Blood-group antigen expression during pancreatic cancer induction in hamsters

The expression of blood group-related and tumor-associated antigens was examined in pancreatic adenocarcinomas and in the normal pancreas of hamsters to determine if this expression correlated with the host blood group and/or stage of carcinogenicity, respectively. Pancreatic tumors were induced by 4 weekly treatments of hamsters with N-nitrosobis(2-oxopropyl)amine (BOP) and analyzed immunohistochemically during different stages of tumor progression with polyclonal antibodies (PoAbs) and monoclonal antibodies (MoAbs) against A, B, O and Lewis (Le) isoantigens, including X, Y and CA 19-9 monosialoganglioside (gastrointestinal cancer antigen, GICA), as well as with PoAbs detecting human carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP) and the beta-subunit of human chronic gonadotropin (beta-HCG). The red blood cells of both control and tumor-bearing hamsters expressed AB and Le(a+b+)-like blood group types, as detected by polyvalent antisera. However, none of the MoAbs reacted with the hamster red blood cells. In the pancreas, all PoAbs against blood group antigens reacted with hyperplastic ducts and ductules at very early stages of carcinogenesis, as well as with neoplastic lesions, but not with normal pancreatic cells, except for the acinar cells, which were stained with PoAb-B, PoAb-Lea and PoAb-Leb. None of the MoAbs showed any affinity for the normal pancreatic cells; however, they reacted to various degrees with induced hyperplastic and neoplastic tissue. Reactivities of several MoAbs with malignant cells were greater than those with hyperplastic lesions: MoAb-B was highly reactive with all induced lesions, MoAb-A less reactive, and MoAb-H and MoAb-Ley (which has 6 sugar chains) detected only some cancer cells. Neither of the two MoAb-Lex (with 5 carbohydrate chains) reacted with carcinoma cells, although they did bind to a few hyperplastic cells. Neither MoAb-Lea and MoAb CA 19-9, nor PoAbs against CEA, AFP and beta-HCG, reacted with any normal, hyperplastic or malignant cells. These results demonstrate the differential reactivity of these PoAbs and MoAbs in normal and malignant pancreatic tissue and show that blood group antigens, especially the B isoantigens, are specific markers for induced pancreatic duct tumors in hamsters.

Presence of two distinct acinar cell populations in human pancreas based on their antigenicity

The immunohistochemical localization of ABH- and Lewis (Le)-related blood group antigens, including CA 19-9, a sialylated Lea antigen, was examined using monoclonal antibodies (MoAbs) in 18 normal human pancreases and compared with ABH blood group antigenicity of the individuals. Acinar cells expressed ABH, Leb, Ley, and in some cases, Lex antigen in various proportions, but not Lea and CA 19-9. The reactivity of Leb and Ley was similar with regard to cellular localization and specificity. In all specimens but one, the distribution of Leb (and Ley) and H antigens on the one hand, and of A or B antigens on the other, showed a reciprocal relationship, in that one group of acini expressed Leb (and Ley) and H antigens, but lacked any A or B antigens (type 1 acinar cell); another group of acinar cells had A or B antigens, but expressed neither Leb (Ley) or H antigens (type 2 acinar cell). In ductal cells, four of eight individuals with blood group A, two of three with blood group B, and five of six with blood group O expressed the appropriate antigen, while the remainder did not. Lea antigen was expressed primarily by centroacinar and terminal ductular and ductal cells of medium-sized ducts of all specimens, whereas Leb was present in the cells of small and large ducts in all but four cases. The reactivity of ductal and ductular cells to Lex was negative, except for one case. MoAb-Ley and MoAb 19-9 reacted only with a few ductal cells in six (33%) and 12 cases (67%), respectively. There was no relationship in the expression of Le-related antigens between acinar and ductal/ductular cells; nor were there any sex difference with regard to the binding patterns of any antibodies. However, age appeared to influence the reactivity of some antibodies with acinar cells. Islet cells did not react with any of the antibodies. The results indicate that, although the antigenicity of epithelial cells can be affected by the host blood group types, there might be several regulatory systems for expression of blood group antigens in a cell-specific pattern.