Are pancarcinoma T and Tn differentiation antigens?

Placental colonization by Fusobacterium nucleatum is mediated by binding of the Fap2 lectin to placentally displayed Gal-GalNAc

While the existence of an indigenous placental microbiota remains controversial, several pathogens are known to be involved in adverse pregnancy outcomes. Fusobacterium nucleatum is an oral bacterium that is one of several bacteria associated with preterm birth. Oral fusobacteria translocate to the placenta hematogenously; however, the mechanisms localizing them to the placenta remain unclear. Here, using peanut agglutinin, we demonstrate that the level of Gal-GalNAc (Galβ1-3GalNAc; Thomsen Friedenreich antigen) found on trophoblasts facing entering maternal blood rises during gestation and is recognized by the fusobacterial Fap2 Gal-GalNAc lectin. F. nucleatum binding to human and mouse placenta correlates with Gal-GalNAc levels and is reduced upon O-glycanase treatment or with soluble Gal-GalNAc. Fap2-inactivated F. nucleatum shows reduced binding to Gal-GalNAc-displaying placental sections. In a mouse model, intravenously injected Fap2-expressing F. nucleatum, but not a Fap2 mutant, reduces mouse fetal survival by 70%.

Fusobacterium nucleatum and cancer

Accumulating evidence demonstrates that the oral pathobiont Fusobacterium nucleatum is involved in the progression of an increasing number of tumors types. Thus far, the mechanisms underlying tumor exacerbation by F. nucleatum include the enhancement of proliferation, establishment of a tumor‐promoting immune environment, induction of chemoresistance, and the activation of immune checkpoints. This review focuses on the mechanisms that mediate tumor‐specific colonization by fusobacteria. Elucidating the mechanisms mediating fusobacterial tumor tropism and promotion might provide new insights for the development of novel approaches for tumor detection and treatment.

Profiling of Naturally Occurring Antibodies to the Thomsen-Friedenreich Antigen in Health and Cancer: The Diversity and Clinical Potential

The Thomsen-Friedenreich (TF) antigen is expressed in a majority of human tumors due to aberrant glycosylation in cancer cells. There is strong evidence that humoral immune response to TF represents an effective mechanism for the elimination of cancer cells that express TF-positive glycoconjugates. The presence of naturally occurring antibodies to tumor-associated TF and cancer-specific changes in their levels, isotype distribution and interrelation, avidity, and glycosylation profile make these Abs a convenient and ubiquitous marker for cancer diagnostics and prognostics. In this review, we attempt to summarize the latest data on the potential of TF-specific Abs for cancer diagnostics and prognostics.

A conserved major facilitator superfamily member orchestrates a subset of O-glycosylation to aid macrophage tissue invasion

Aberrant display of the truncated core1 O-glycan T-antigen is a common feature of human cancer cells that correlates with metastasis. Here we show that T-antigen in Drosophila melanogaster macrophages is involved in their developmentally programmed tissue invasion. Higher macrophage T-antigen levels require an atypical major facilitator superfamily (MFS) member that we named Minerva which enables macrophage dissemination and invasion. We characterize for the first time the T and Tn glycoform O-glycoproteome of the Drosophila melanogaster embryo, and determine that Minerva increases the presence of T-antigen on proteins in pathways previously linked to cancer, most strongly on the sulfhydryl oxidase Qsox1 which we show is required for macrophage tissue entry. Minerva's vertebrate ortholog, MFSD1, rescues the minerva mutant's migration and T-antigen glycosylation defects. We thus identify a key conserved regulator that orchestrates O-glycosylation on a protein subset to activate a program governing migration steps important for both development and cancer metastasis.

Binding of galectin-1 to breast cancer cells MCF7 induces apoptosis and inhibition of proliferation in vitro in a 2D- and 3D- cell culture model

Background

Galectin-1 (gal-1) belongs to the family of β-galactoside-binding proteins which primarily recognizes the Galβ1-4GlcNAc sequences of oligosaccharides associated with several cell surface glycoconjugates. The lectin recognizes correspondent glycoepitopes on human breast cancer cells. Galectin-1 is expressed both in normal and malignant tissues. Lymphatic organs naturally possessing high rates of apoptotic cells, express high levels of Galectin-1. Furthermore galectin-1 can initiate T cell apoptosis. Binding of galectin-1 to trophoblast tumor cells presenting the oncofetal Thomsen-Friedenreich (TF) carbohydrate antigen inhibits tumor cell proliferation. In this study we examined the impact galectin-1 has in vitro on cell proliferation, apoptotic potential and metabolic activity of MCF-7 and T-47D breast cancer cells in dependence to their expression of the Thomsen-Friedenreich (TF) tumor antigen.

Methods

For proliferation and apoptosis assays cells were grown in presence of 10, 30 and 60 μg gal-1/ml medium. Cell proliferation was determined by a BrdU uptake ELISA.

Detection of apoptotic cells was done by M30 cyto death staining, in situ nick translation and by a nucleosome ELISA method. Furthermore we studied the impact galectin-1 has on the metabolic activity of MCF-7 and T-47D cells in a homotypic three-dimensional spheroid cell culture model mimicking a micro tumour environment.

Results

Gal-1 inhibited proliferation of MCF-7 cells (strong expression of the TF epitope) but did not significantly change proliferation of T-47D cells (weak expression of the TF epitope). The incubation of MCF-7 cells with gal-1 raised number of apoptotic cells significantly. Treating the spheroids with 30 μg/ml galectin-1 in addition to standard chemotherapeutic regimes (FEC, TAC) resulted in further suppression of the metabolic activity in MCF-7 cells whereas T-47D cells were not affected.

Conclusions

Our results demonstrate that galectin-1 can inhibit proliferation und metabolic cell activity and induce apoptosis in breast tumor cell lines with high expression levels of the Thomsen-Friedenreich (TF) antigen in monolayer and spheroid cell culture models.

Oxygen governs Galβ1-3GalNAc epitope in human placenta

It is becoming increasingly apparent that the dynamics of glycans reflect the physiological state of cells involved in several cell functions including growth, response to signal molecules, migration, as well as adhesion to, interaction with, and recognition of other cells. The presence of glycoconjugates in human placenta suggests their major role in maternal-fetal exchanges, intercellular adhesion, cellular metabolism, and villous vessel branching. Although several studies have described glycoconjugate distribution in the human placenta descriptions of their physiological function and control mechanisms during placental development are lacking. In this study we investigated the developmental distribution and regulation of placental core 1 O- and N-glycans focusing on early and late first trimester human pregnancy. To define the control mechanisms of the oligosaccharide chains during early placentation process, chorionic villous explants and human trophoblast cell lines were exposed to various oxygen levels. We found that oxygen tension regulates changes in core-1 O-glycan (the disaccharide Galβ1-3GalNAc) epitope expression levels. Moreover, by double affinity chromatography and subsequent analysis with mass spectrometry, we identified in the heat shock protein 90-α (HSP90α) a good candidate as carrier of the Galβ1-3GalNAc epitope at low oxygen tension. Our results support a fundamental role of oxygen tension in modulating glycosylation of proteins during placental development.

Expression of CD176 (Thomsen-Friedenreich antigen) on lung, breast and liver cancer-initiating cells

The cancer-initiating capacity of most malignant tumours is considered to reside in a small subpopulation of cells. Therapeutical interventions should target these cells rather than the tumour mass. Numerous studies have shown that the carbohydrate antigen structure CD176 (Thomsen-Friedenreich antigen, core-1) is present in many types of cancer and absent in normal adult human tissues. In this study, we assessed whether CD176 is co-expressed with CD44 or CD133 [markers of cancer-initiating cells (CIC)] in human lung, breast and liver carcinoma. A variety of human cancer cell lines and surgical specimens of these malignancies were examined. It was found that in most cases the majority of tumour cells stained strongly for CD44 by immunohistochemistry and flow cytometry, whereas CD133 expression was found on a smaller, but varying proportion of cells. Co-expression of CD176 with CD44 was found at a surprisingly high percentage of cancer cells in vitro and in vivo. Co-expression of CD176 with CD133 was also detected, although at a lower rate. Tamoxifen treatment of MDA-435 breast cancer cells enhanced the CD44(+) /CD176(+) phenotype. Evidence is provided through a new sandwich solid-phase enzyme-linked immunosorbent assay (ELISA) suggesting that CD44 is a carrier molecule for CD176 not only in colorectal cancer as previously reported, but also in lung, breast and liver cancer. The expression of CD176 in CIC suggests that it may represent an effective target for tumour therapies.

Glycoprotein and carbohydrate binding protein expression in the placenta in early pregnancy loss

Glycoproteins expressed at the fetal-maternal interface have been shown to exert immunomodulating effects. Glycodelin, hCG and transferrin have been used in in vitro experiments as ligands to block E-selectin-mediated cell adhesion. We found that glycodelin is a strong inhibitor of the E-selectin-mediated cell adhesion with a 10(3)-fold increase in potency compared to the monovalent tetrasaccharide sialyl Lewis X. HCG with distinct carbohydrate expression is also an effective selectin antagonist, whereas the potency of transferrin is low. This could indicate a possible role of glycodelin, hCG and transferrin in preventing leukocyte adhesion to the fetal trophoblast. In decidual tissue of abortion patients, glycodelin expression was significantly reduced compared to normal gestation. These results were confirmed by in situ hybridization. Moreover, glycodelin expression in endometrial cells in vitro could be stimulated by addition of hCG. Because hCG is down-regulated in women with abortion, we speculate that hCG could be one of the factors regulating glycodelin expression. Galectins are structurally related proteins with the ability to bind beta-galactosides through a conserved carbohydrate recognition domain. Galectin-1 (gal-1) expression in the syncytiotrophoblast is down-regulated in early pregnancy loss. Gal-1 recognizes the Thomsen-Friedenreich disaccharide (Galbeta1-3GalNAc-) on the syncytiotrophoblast and extravillous trophoblast. Gal-1 also inhibited trophoblast cell proliferation but did not induce apoptosis in BeWo cells. Ligation of Gal-1 on trophoblast cells may have regulatory effects on trophoblast cell differentiation. Decreased expression of Gal-1 may partly explain disturbed trophoblast differentiation during early placentation leading to early pregnancy loss.

The human endometrium expresses the glycoprotein mucin-1 and shows positive correlation for Thomsen-Friedenreich epitope expression and galectin-1 binding

Mucin 1 (MUC1) is a glycoprotein in human endometrium and is abundant at the luminal epithelial surface in the receptive phase. It has a highly glycosylated ecto-domain that contains keratan sulfate chains, that disappears at the time of implantation. In addition, the glycoforms on MUC1 differ in fertile and infertile women. Therefore the aims of this study were investigations on glycosylation of MUC1 with the Thomsen-Friedenreich (TF) epitope on normal human endometrium throughout the menstrual cycle and binding of galectin-1 on the TF epitope in the endometrium and the expression of galectin-1 on the human oocyte. Human endometrial tissue was obtained from 54 premenopausal patients and was immunohistochemically analyzed with monoclonal antibodies against MUC1, TF epitope, galectin-1, and biotinylated galectin-1. In addition, human oocytes were analyzed for TF, galectin-1 expression, and galectin-1 binding. We identified a significant upregulation of MUC1 and TF epitope and, in addition, galectin-1 binding in glandular epithelium and epithelial apical surface tissue from proliferative to secretory phase. With double staining experiments, we identified a coexpression of TF and MUC1 in the early secretory phase and galectin-1 binding to TF during the same period of time. In addition we identified TF epitope and galectin-1 expression plus binding on the human oocyte and irregularly fertilized oocytes. Upregulation of TF epitope on the glandular epithelium and epithelial apical surface tissue in the secretory phase and binding of galectin-1 at the same time show the possibility of galectin-1-mediated trophectoderm binding to the endometrium within the window of implantation.

Expression of galectin-1, -3 (gal-1, gal-3) and the Thomsen-Friedenreich (TF) antigen in normal, IUGR, preeclamptic and HELLP placentas

BACKGROUND

Galectin-1 (gal-1) and galectin-3 (gal-3), which are members of the mammalian beta-galactoside-binding proteins, recognise preferentially (Galbeta1-4GlcNAc) sequences of several cell surface oligosaccharides. In addition, gal-1 also binds to the Thomsen-Friedenreich (TF) antigen (Galbeta1-3GalNAc-).

MATERIALS AND METHODS

Slides of frozen and paraffin-embedded placental tissue of patients with fetal intrauterine growth retardation (IUGR), preeclampsia, haemolysis, elevated liver enzymes, low platelets (HELLP) and normal term placentas were incubated with monoclonal and polyclonal antibodies against gal-1, gal-3 and TF. Staining reaction was performed with the avidin-biotinylated peroxidase complex (ABC) reagent. The intensity of the immunohistochemical reaction on the slides was analysed using a semi-quantitative score. The identity of galectin-expressing cells was analysed by using a double immunofluorescence method.

RESULTS

We demonstrated immunohistochemically that the expression of gal-1 and gal-3 on the extravillous trophoblast (EVT) is significantly up-regulated in preeclamptic and HELLP placentas and unchanged compared with normal controls in IUGR placentas. The expression of the TF antigen is significantly up-regulated in IUGR and preeclamptic extravillous trophoblast cells and unchanged in HELLP placentas compared with normal controls. In addition, the expression of gal-1 is significantly up-regulated in the decidual tissue of preeclamptic placentas and in the villous trophoblast tissue of HELLP placentas.

CONCLUSION

Our data showed that gal-1, gal-3 and TF were up-regulated on the membrane of EVT in preeclamptic placentas. In addition, the expression of gal-1 is significantly up-regulated in decidual tissue of preeclamptic placentas and villous trophoblast tissue of HELLP placentas. Taking into consideration the results of this study, we speculate that expression of both galectins and TF on the membrane of preeclamptic EVT and up-regulation of gal-1 in preeclamptic decidual cells may at least in part compensate for the apoptotic effects of maternal immune cells.

The use of levoglucosenone and isolevoglucosenone as templates for the construction of C-linked disaccharides

Because of their functionalities (enone, ketone, and acetal) and their bicyclic structure (steric factors), levoglucosenone (1,6-anhydro-3,4-dideoxy-beta-D-glycero-hex-3-enopyran-2-ulose) and isolevoglucosenone (1,6-anhydro-2,3-dideoxy-beta-D-glycero-hex-3-enopyran-4-ulose) are useful templates for the convergent and combinatorial synthesis of (1-->2), (1-->3), and (1-->4)-linked C-disaccharides in reactions combining them with sugar-derived carbaldehydes. Synthetic methods relying on conjugate nucleophilic additions of these enones, their combination with aluminum reagents and aldehydes (Baylis-Hillman reaction) and modified Takai-Hiyama-Nozaki-Kishi couplings of enol triflates derived from them with sugar-derived aldehydes are reviewed. Highly stereoselective methods have thus been developed. These allow the generation of disaccharide mimetics with a high molecular diversity.

Prognostic impact of Thomsen-Friedenreich tumor antigen and disseminated tumor cells in the bone marrow of breast cancer patients

PURPOSE

The Thomsen-Friedenreich antigen (TF, CD176) is a specific oncofetal carbohydrate epitope (Gal beta1-3GalNAc alpha-O-Ser/Thr) expressed on the surface of various carcinomas. It mediates endothelium adhesion and formation of metastases. As it also causes immune response, its prognostic impact is indeterminate. The presence of disseminated tumor cells in the bone marrow of breast cancer patients (DTC-BM) indicates worse prognosis. We examined the expression of TF in primary breast cancer tissue of 265 patients with known BM status at the time of first diagnosis.

METHODS

BM aspiration, cytospin preparation and immunocytochemical staining with the anti-Cytokeratin antibody A45 B/B3 was done following a standardised protocol. TF expression was examined immunohistochemically on Tissue Micro Arrays (TMA) with the anti-TF antibody A78-G/A7. Evaluation was done using the immunoreactive score (IRS).

RESULTS

Median IRS for TF expression was 2 (0-12). 68 of 265 patients (25.7%) showed DTC-BM with a median of 2/2 x 10(6) cells (1-1500). There was no correlation between TF expression and DTC-BM. After a median follow up of 60.1 months (7-119), the detection of DTC-BM showed prognostic significance for overall survival (OS, p = 0.034), whereas TF positivity (IRS > 2) indicated prolonged disease-free (p = 0.01), distant disease-free (p = 0.005), and overall survival (p = 0.005).

DISCUSSION

Patients with TF-positive tumors had a significantly better prognosis. Dissemination routes, TF-mediated metastasis formation, and the immunogeneity of TF might determine the prognostic impact of TF expression in different tumor entities. Further characterisation of primary tumors and DTC-BM could help to improve the biological understanding of metastases and develop targeted therapies.

Binding of galectin-1 (gal-1) to the Thomsen–Friedenreich (TF) antigen on trophoblast cells and inhibition of proliferation of trophoblast tumor cells in vitro by gal-1 or an anti-TF antibody

Galectin-1 (gal-1), a member of the mammalian beta-galactoside-binding proteins, recognizes preferentially Galbeta1-4GlcNAc sequences of several cell surface oligosaccharides. We demonstrate histochemically that the lectin recognizes appropriate glycotopes on the syncytiotrophoblast and extravillous trophoblast layer from second trimester human placenta and on BeWo chorion carcinoma cells. Gal-1 binding to BeWo cells was diminished by the Thomsen-Friedreich (TF)-disaccharide (Galbeta1-3GalNAc-) conjugated to polyacrylamide (TF-PAA). Gal-1 also inhibited BeWo cell proliferation in a concentration-dependent manner. Similar antiproliferative effects were also observed with an anti-TF monoclonal antibody (mAb, A78-G/A7). Therefore, we conclude that ligation of Galbeta1-4GlcNAc and Galbeta1-3GalNAc epitopes on BeWo cells may have regulatory effects on cell proliferation.

C-Linked Disaccharide Analogue of the Thomsen-Friedenreich (T)-Epitope α-O-Conjugated toL-Serine

Condensation of a silylated beta-D-galactopyranosylaldehyde (3) with isolevoglucosenone (4) in the presence of Et(2)AlI provided bicyclic enone 5. Subsequent addition of BnNHOMe gave adduct 6, which was converted into 4-O-acetyl-1,6-anhydro-3-C-[(1 R)-1,3,4,5,7-penta-O-acetyl-2,6-anhydro-D-glycero-L-manno-heptitol-1-C-yl]-2-azido-2,3-dideoxy-beta-D-galacto-hexopyranose after liberation of the 2-amino group, its transformation into a 2-azido moiety, desilylation, and peracetylation. Ring-opening of the 1,6-anhydro galactopyranosyl unit and O-glycosidation with Fmoc-Ser-O-tBu afforded a 5:1 mixture of alpha- and beta-galactosides. Treatment with CH(3)COSH gave pure N-[(9H-fluoren-9-ylmethoxy)carbonyl]-{4,6-di-O-acetyl-3-C-[(1 R)-2,6-anhydro 1,3,4,5,7-penta-O-acetyl-D-glycero-L-manno-heptitol-1-C-yl]-2-[(N-acetyl)amino]-2,3-dideoxy-alpha-D-galactopyranosyl}-l-serine tert-butyl ester (2), a protected form of a C-disaccharide analogue of the Thomsen-Friedenreich (or T) epitope (beta-D-Galp-(1-->3)-alpha-D-GalNAcp) alpha-O-conjugated to L-serine.

Characterisation of disseminated tumor cells in the bone marrow of breast cancer patients by the Thomsen-Friedenreich tumor antigen

The detection of disseminated tumor cells in the bone marrow (DTC-BM) of breast cancer patients has proved prognostic significance in all stages of the disease. Further characterisation of those cells could help to improve the biological understanding of metastases, develop targeted therapies and define surface markers for enrichment techniques. The Thomsen-Friedenreich (TF) antigen has been shown to be a tumor specific antigen in breast cancer. The aim of this study was to investigate the expression of TF on DTC-BM in 25 patients. Bone marrow samples were first double-stained by a Cy3 conjugated cytokeratin (CK) antibody (ab) A45 B/B3 (IgG) and anti-TF ab Nemod 2 (IgM), followed by Cy2 conjugated goat anti-mouse IgM ab. For further characterisation samples were also double-stained with anti-TF ab Nemod 2 (IgM), followed by Cy2 conjugated goat anti-mouse IgM ab, and anti MUC1 ab A76-A/C7 IgG, followed by Cy3 conjugated goat anti-mouse IgG. CK positive DTC-BM showed co-expression of TF antigen in 22/23 patients (96%) and 61 of 62 detected cells (98%). Mononuclear BM cells without CK expression were also negative for TF. All of the TF positive cells showed strong MUC1 expression. This is the first study showing co-expression of CK and TF as markers of DTC-BM. Double staining experiments of TF and MUC1 expression showed that MUC1 is the carrier protein of TF in these cells. As TF is a specific marker of DTC-BM, it could be used as a target for antibody based therapy and immunomagnetic enrichment techniques for the isolation of DTC-BM.

Lectins: from basic science to clinical application in cancer prevention

Many physiological functions are attributable to lectin-carbohydrate interactions. Lectins are currently being studied for their ability to destroy tumour growth by binding to specific carbohydrate motifs on cancer cells. Cell-surface molecules, including growth factor receptors are often glycosylated, and lectins may act by binding to these. Certain lectins effect the proliferation of intestinal epithelial cells. This effect is cell-type and lectin specific and occurs in the intestine of intact animals, in human colonic explants and colorectal cancer cell lines. Lectins present in mammalian tissue are involved in cell-matrix adhesion, differentiation, lymphocyte circulation and immunomodulation. Mammalian lectins contribute to detection, diagnosis and prognosis of tumour cells, and can be targeted for therapy. New lectins of plant and mammalian origin that have one or more of these functions are currently being developed as tools that could be used to target tumour cells.

Differential expression of the cancer associated antigens T (Thomsen-Friedenreich) and Tn to the skin in primary and metastatic carcinomas

AIM

To study the immunohistochemical expression of the Thomsen-Friedenreich antigen (T) and its precursor, Tn, in the skin in various cancers.

METHODS

T and Tn antigens were studied with monoclonal antibodies in 91 primary premalignant and malignant lesions, 13 cases of Paget's disease, and 26 carcinomas metastatic to the skin. The material had been collected over a 10 year period, formalin fixed, and paraffin embedded. Diagnoses had been made after examination of standard histological sections, supplemented when needed by appropriate immunohistochemical staining.

RESULTS

21% and 29% of the primary cutaneous premalignant and malignant epithelial tumours expressed the Tn and T antigens, respectively. By contrast, 81% of metastatic carcinomas to the skin were Tn positive, while only 23% of them expressed the T antigen. All cases of Paget's disease were Tn positive but only 15% of them expressed the T antigen. The 21 nonepithelial tumours (including melanomas) were as a rule unreactive.

CONCLUSIONS

The accumulation of the precursor (Tn) antigen in tumours metastasising to the skin highlights the incomplete glycosylation of carbohydrate antigens occurring in these tumours. The predominant Tn versus T antigen expression appears to be a useful immunohistochemical feature which may aid in the differentiation of primary cutaneous carcinomas from metastatic tumours.

Development and characterization of monoclonal antibody to T-antigen: (gal beta1-3GalNAc-alpha-O)

The saccharide antigen, Gal beta1-3GalNAc or T antigen, is of biologic importance in many systems. It is a tumor-associated carbohydrate antigen, a temporally expressed antigen in germinal center B cells and cortical T cells, a parasite-associated antigen, a spermatozoa vitality marker and an antigen on aged red blood cells. It may play a role in normal cellular adhesion and in tumor cell metastasis. Well characterized monoclonal antibodies (MAb) to Gal beta1-3GalNAc will be useful for further studies in these areas. We developed an IgG3 MAb to Gal beta1-3GalNAc by immunizing the mice with a synthetic Gal beta1-3GalNAc-BSA conjugate. The MAb was analyzed using inhibition enzyme immunoassays with related synthetically prepared sugars to determine the restrictions involved in the antibody binding. Use of synthetic sugars as competitors enabled us to delineate the epitope restrictions on the binding activity of this monoclonal and will enable use of this MAb in studies concerning the biologic importance of this disaccharide.

Stimulation of proliferation in human colon cancer cells by human monoclonal antibodies against the TF antigen (galactose beta1-3 N-acetyl-galactosamine)

In many tissues, the TF (Thomsen-Friedenreich) blood group antigen (Galbeta1-3GalNAc alpha-) behaves as an onco-foetal carbohydrate antigen, showing increased expression in malignancy and hyperplasia. Dietary lectins which bind the TF antigen have marked effects on proliferation of epithelial cells without cytotoxicity. This led us to speculate that anti-TF antibodies, including those that naturally occur in humans, might have similar effects. Five anti-TF antibodies, TF2 (human), TF5 (human), 5A8 (mouse), 8D8 (mouse) and BM22 (mouse), but not TFI (human) or 49H.9 (mouse), showed marked dose-dependent stimulation (95-192%) of [3H]thymidine incorporation by HT29 human colon cancer cells. Similar stimulation of proliferation of HT29 cells by these monoclonal antibodies (MAbs) was found when cell count assessment was used. Antibody-stimulated proliferation was inhibited by co-incubation with glycoproteins expressing Galbeta1-3GalNAc alpha- (asialo glycophorin or [Galbeta1-3GalNAc alpha-O-p-aminophenyl]n-human serum albumin). A proliferative effect of these antibodies was also demonstrated on human colon cancer cell lines LS174T and HT29-MTX but not on Caco-2 cells. Although immunoblotting showed similar binding patterns of all the antibodies on HT29 cell membrane extracts, there was little correlation between cell surface binding assessed by immunofluorescence and proliferative response, and internalization of the biotinylated antibody TF5 was demonstrated by confocal microscopy. Our results provide further evidence that cell surface glycoproteins which express TF antigen may play an important role in the regulation of cell proliferation and also suggest that human anti-TF antibodies may have proliferative effects on cells which express TF antigen.

A new monoclonal antibody (A78-G/A7) to the Thomsen-Friedenreich pan-tumor antigen

A new monoclonal antibody to the Thomsen-Friedenreich (TF) antigen (or, more precisely, epitope; Gal beta 1-3GalNAc-) has been developed that is specific for both anomeric forms of this disaccharide (TF alpha and TF beta, including related structures on glycolipids), and not assay restricted. We demonstrate that this avid antibody (A78-G/A7) is well suited for immunohistochemistry on paraffin-embedded and cryosectioned tissues, immunoblotting, ELISA techniques, and hemagglutination. Immunohistochemistry on paraffin sections does not require proteolytic or microwave pretreatment. The binding characteristics of this antibody are largely independent of variations in pH (6.0-8.2) and temperature (4-37 degrees C). Immunoblotting with KG-1 (human acute myelogenous leukemia) cells revealed a series of TF-active glycoproteins with a main band at about 155 kDa. Immunoprecipitation was performed using a new technique applicable to IgM-type antibodies.

Blood group antigens as tumor markers, parasitic/bacterial/viral receptors, and their association with immunologically important proteins

Blood group antigens (BGAs) are chemical moieties on the red blood cell (RBC) membrane. Some BGAs (e.g., A, B, H, Lewis, P, I) are widely distributed throughout the body and may not be primarily erythroid antigens. Statistical correlations with ABO blood groups and disease have been made for years and have been highly controversial. It is not known if BGAs have a biological function. There are increasing reports of BGAs [e.g., Le(x) (an isomer of Le(a)), Le(y) (an isomer of Le(b)), T, Tn, "A-like"] appearing as "new" antigens on malignant tissue. Their presence and membrane density appears to correlate with the metastatic potential of the tumor. This often parallels loss of normal BGAs (e.g., ABH) from the tissue. Some of these antigens have been shown to influence the humoral and cellular response and have been used in assays to determine preclinical cancer, and in tumor immunotherapy. Interactions of some parasites and bacteria with human cells have been shown to depend on the presence of certain BGAs. P. vivax malarial parasites only enter human RBCs when the Fy6 Duffy blood group protein is present on the RBCs. Certain E. coli will only attach to the epithelial cells of the urinary tract if P or Dr BGAs are present in the epithelial cells. The P antigen is also the RBC receptor for Parvovirus B19. Leb has recently been found to be the receptor for H. pylori in the gastric tissue. The high frequency BGA, AnWj, is the RBC receptor for H. influenzae. BGAs have been shown to be associated closely with some important complement proteins. Ch/Rg BGAs have been found not to be true BGAs but are RBC-bound C4 (C4d). Knops/McCoy/York BGAs have been located on the C3b/C4b receptor (CR1). The high frequency BGAs of the Cromer (Cr) system are located on decay accelerating factor (DAF or CD55). Cartwright (Yt) BGAs are located on RBC acetylcholinesterase molecules. DAF and acetylcholinesterase are on phosphatidylinositol-glycan (PIG) linked proteins. When the PIG anchor is missing from RBCs, as in paroxysmal nocturnal hemoglobinuria, the affected RBCs lack all Cr, Yt, JMH, Hy/Gy, Do and Emm BGAs. The most important ligand for P, E and L selectins is sialyl-Le(x). This interaction is the tethering stage that start the leukocytes' journey from the circulation into the tissue. It appears that malignant cells may move through tissue in a similar way and may explain the close association of Le(x) with metastasis. Thus, there are increasing data suggesting a biological role for BGAs unrelated to the RBC.

Localization and identification of T-(Gal beta 1-3GalNAc alpha 1-O-R) and T-like antigens in experimental rat bladder cancer

A mouse monoclonal antibody and a rabbit polyclonal antibody against the T-antigen (Gal beta 1-3GalNAc alpha 1-O-R) were used to study the distribution of T-antigens in an experimental rat bladder cancer model. Neoplasia was induced in 28 rats by intravesical installation of N-nitroso-N-methylurea (NMU) dissolved in acetate buffer. Fifteen rats were installed with acetate buffer, and served as controls. Urothelial samples were taken from all animals, the atypia was graded and detailed data on the location of the antibody binding structures were obtained by immunohistochemical methods. In addition, Western Blots of glycoproteins and thin-layer-chromatography (TLC) immunostainings of glycolipids extracted from normal and malignant tissue were performed to characterize the molecules presenting T-antigens. Examination of the histologic distribution of T-antigens showed that both the monoclonal and the polyclonal reagents reacted with atypical cells in proportion to the grade of atypia, but showed no reaction in invasive cells. These results confirm previously obtained data on the T-antigen using peanut (arachis hypogaea) agglutinin (PNA), and support the structure identity as being the classical O-linked mucin type T-antigen. Western blots of tumor glycoproteins showed that the monoclonal and the polyclonal antibody reacted with epitopes different from that of PNA, but all the probes correlated with atypia. In addition PNA, as the only anti-T reagent, bound to glycolipid. By using well characterized and highly specific immunological reagents the present study shows that the T-antigen is a highly selective marker of urothelial atypia.

Histochemical and cytochemical localization of blood group antigens

The oligosaccharide structures of blood group antigens are not the primary gene products; they are constructed in a stepwise manner by adding particular sugar to precursor oligosaccharides via several glycosyltransferases coded for by different blood group genes (Watkins 1966, 1978, 1980). Consequently, final profiles of antigens expressed in each cell type are influenced by many different factors such as the intrinsic composition of glycosyltransferase species which are defined by the genotype of the individuals, relative activity or amount of these enzymes (repression, derepression or induction of the enzymes), competition between enzymes with overlapping substrate specificity, the organization of the enzymes in membranes, utilizability of precursors and specific substrate sugars, and the activity level of degradating enzymes. Changes in the antigen profiles during maturation, differentiation and malignant transformation are thought to be intimately related to the variability of these factors. Although great importance attaches to histo- and cytochemical information on the distribution and levels of glycosyltransferases and messenger RNA corresponding to the relevant enzyme, detailed and precise localization of the blood group antigens and their variants is the base line for analyzing these complex factors. On the basis of individual genotype and histochemical findings about the antigen distribution and the interrelationship between cells and cellular components producing different antigenic structures (cellular and subcellular mosaicism), we can deduce precursor oligosaccharide levels as well as the status of gene activation and its primary product, glycosyltransferases. Thus, these findings are a prerequisite for further analysis at the molecular genetic level. As emphasized in this article, lectin staining or immunostaining methods with MAbs combined with glycosidase digestion procedures are powerful tools for in situ analysis of carbohydrate structures in histochemical systems. Although in some cases valuable results have been obtained by applying the technique, our knowledge concerning the distribution of complex carbohydrate structures is still far from satisfactory. Along with well defined MAbs and lectins, the key to developing our methods further is successful introduction of glycosidases, in particular, endoglycosidases since these reagents are indispensable for analyzing the inner core structures and glycoconjugate species of the blood group antigens. Application of these techniques at the ultrastructural level is an alluring possibility, even though many difficulties must be overcome. Although their functional roles have not yet been determined, a diverse array of macromolecules is known to be decorated with blood group-related antigens.(ABSTRACT TRUNCATED AT 400 WORDS)

Nuclear volume and expression of T-antigen, sialosyl-Tn-antigen, and Tn-antigen in carcinoma of the human bladder. Relation to tumor recurrence and progression

The T-antigen system and the mean nuclear volume have been proposed as risk variables in bladder tumors. This study includes 34 patients with initially noninvasive (Ta) transitional cell carcinomas who experienced different courses of disease. Tissue specimens of primary tumors were analyzed for the expression of T-antigen, Tn-antigen, and sialosyl-Tn-antigen using monoclonal antibodies (MoAb) and the lectin peanut agglutinin (PNA) in an indirect immunoperoxidase method. In addition, the mean nuclear volume was estimated by morphometry. Tissue from 7 of 13 patients (54%) who had invasive disease during a follow-up period of 5 years expressed T-antigen, as defined by MoAb HH8 in the primary tumor, whereas tissue of only 3 of 21 patients who did not have invasive disease expressed the antigen (P less than 0.02). No association was found between tumor progression to invasion and the expression of Tn-antigen or sialosyl-Tn-antigen. Tn-antigen expression was partially lost in invasive tumors (P less than 0.03) when compared with the expression in primary noninvasive tumors. A high mean nuclear volume in tissue specimens of primary tumors correlated with a progression to invasive disease (P less than 0.01). A significantly (P less than 0.003) higher mean nuclear volume was found in tumor areas that were positive for PNA compared with areas that were negative for PNA in primary tumors. A significantly lower mean nuclear volume was found in Tn-antigen-positive invasive Grade 3 tumor areas than in Tn-antigen-negative areas (P less than 0.005). The combined use of T-antigen expression and mean nuclear volume is of potential clinical interest for determining patients who are at high risk of disease progression.

Expression of Tn, sialosyl Tn, and T antigens in human pancreas

Carbohydrate antigens representing some of the initial steps in mucin O-linked glycosylation were examined in specimens of normal pancreas, chronic pancreatitis, and pancreatic adenocarcinoma. Tn antigen, recognized by Vicia villosa lectin, was expressed by all specimens of normal pancreas (acinar cells) and pancreatic cancers and all but one case of chronic pancreatitis. Sialosyl Tn antigen, recognized by monoclonal antibody TKH2, was expressed in a cancer-associated fashion, being completely absent in normal pancreas but expressed by 56% of chronic pancreatitis and 97% of pancreatic cancers. T antigen, recognized by monoclonal antibody AH9-16, was expressed in 68% of normal pancreas (acinar cells), 67% of chronic pancreatitis, and 48% of pancreatic cancer tissues. These results indicate that normal acinar cells of the pancreas are capable of expressing selected carbohydrate structures associated with the initial steps of mucin glycosylation. The marked expression of sialosyl Tn compared with T antigen in pancreatic cancers suggests that with malignant transformation there is selective usage of glycosyltransferase enzymes involved in mucin oligosaccharide synthesis.

O-linked mucin-type glycoproteins in normal and malignant colon mucosa: lack of T-antigen expression and accumulation of Tn and sialosyl-Tn antigens in carcinomas

The expression of carbohydrate core-structures on O-linked glycoproteins was examined in fetal (n = 6), infantile (n = 2), normal adult (n = 15), and malignant (n = 22) colorectal tissue by means of monoclonal antibodies (MAbs) specific for Tn (GalNAc alpha 1-O-R), sialosyl-Tn (NeuAc alpha 2-6GalNAc alpha 1-O-R), and T (Gal beta 1-3GalNAc alpha 1-O-R) antigens. Immunolabelling of solubilized malignant tissue, separated by SDS-PAGE, showed expression of Tn and sialosyl-Tn antigens on 3 molecules of similar mw (230, 210, and 170 kDa), whereas no T antigens could be detected. Immunohistochemical techniques showed that fetal colon mucosa expressed Tn antigens but no sialosyl-Tn antigens. Infantile colon mucosa, however, expressed Tn as well as sialosyl-Tn antigens, and normal adult colon mucosa cells expressed no Tn antigens but sialosyl-Tn in 2 out of 6 biopsies from cecum, which indicates occurrence post partum of alpha-6-NeuAc-transferase. Endothelium in normal adult mucosa showed expression of both Tn and sialosyl-Tn antigens; 82% of carcinoma tissue sections expressed Tn antigens, and 73% expressed sialosyl-Tn antigens in mucin or cytoplasm, or on luminal cell membranes. T antigens could be detected neither in normal mucosa cells at any stage of development, nor in carcinomas. The possibility exists that this could be due to masking of T antigen. Mucin-type blood-group A antigens which contain an internal T-disaccharide were demonstrated in 4 out of 4 A1 tumors by means of MAb HH5. However, urea-containing SDS-PAGE analysis demonstrated an HH5 binding to molecules different from those binding anti-Tn. In remote morphologically normal and abnormal crypts in colons from carcinoma patients, both Tn and sialosyl-Tn antigens were expressed in secreted mucin in 40% of the cases. The data indicate an expression of O-linked Tn and sialosyl-Tn core structures in fetal and infantile colon and in colorectal carcinomas.

The pathobiology of red cell cryptantigen exposure

This article has defined in part the circumstances in which red cell cryptantigen exposure occurs and its significance in children. Bacteria-induced cryptantigens (T and Tk) are the most commonly encountered and, when present, suggest a guarded prognosis, a complicated clinical course, and a need for care in transfusion management with particular attention to the avoidance of plasma-containing products. Nonbacterial-induced cryptantigens (Th and Tn) are much less commonly seen and are encountered as a complicating feature of a serious hematologic condition and may be a potential source of confusion in the neonate.