Tumor-Associated Glycolipid Antigens and Modified Blood Group Antigens

Stage-specific embryonic antigen-3 (SSEA-3) and β3GalT5 are cancer specific and significant markers for breast cancer stem cells

The discovery of cancer stem cells (CSCs), which are responsible for self-renewal and tumor growth in heterogeneous cancer tissues, has stimulated interests in developing new cancer therapies and early diagnosis. However, the markers currently used for isolation of CSCs are often not selective enough to enrich CSCs for the study of this special cell population. Here we show that the breast CSCs isolated with CD44(+)CD24(-/lo)SSEA-3(+) or ESA(hi)PROCR(hi)SSEA-3(+) markers had higher tumorigenicity than those with conventional markers in vitro and in vivo. As few as 10 cells with CD44(+)CD24(-/lo)SSEA-3(+) formed tumor in mice, compared with more than 100 cells with CD44(+)CD24(-/lo). Suppression of SSEA-3 expression by knockdown of the gene encoding β-1,3-galactosyltransferase 5 (β3GalT5) in the globo-series pathway, led to apoptosis in cancer cells specifically but had no effect on normal cells. This finding is further supported by the analysis of SSEA-3 and the two related globo-series epitopes SSEA4 and globo-H in stem cells (embryonic stem cells and induced pluripotent stem cells) and various normal and cancer cells, and by the antibody approach to target the globo-series glycans and the late-stage clinical trials of a breast cancer vaccine.

Shift from Rh-positive to Rh-negative phenotype caused by a somatic mutation within the RHD gene in a patient with chronic myelocytic leukaemia

We report a female patient whose Rh phenotype shifted from RhD-positive to RhD-negative over a 3-year period (1991-94), during which time she was treated with mastectomy (1992) and local irradiation for a low-grade recurrent breast cancer. She was diagnosed with chronic myeloid leukaemia in 1994, and has since then received chemotherapy. The patient was repeatedly typed as O, RhD-positive between 1965 and 1991 and was repeatedly found RhD-negative after 1994. Bcr-Abl transcripts typical of Ph1 chromosome were detected. Molecular analysis indicated that the patient was heterozygous at the RH locus, carrying one haplotype in which the RHD gene exhibited a single nucleotide deletion (G600) resulting in a frameshift and premature stop codon, and a normal RHCE gene (allele Ce). The second haplotype contained only the RHCE gene (allele ce) and was normal. Further analysis carried out on total leucocytes, purified neutrophils, EBV-lymphoblastoid cell line and cultured erythroblasts indicated that the G600 deletion was restricted to the myeloid lineage. No modification of other blood group antigens could be detected. These findings suggest a somatic mutation which most probably occurred in a stem cell common to the myeloid lineage.

The identification of a neutral glycosphingolipid antigenic marker for metastatic cells in the R3230AC rat mammary adenocarcinoma

The process of metastasis is a complex process involving numerous steps, and it is thought that cells able to complete all of these steps and form metastatic foci form a unique subpopulation of cells within the tumor. To study this metastatic subpopulation, a marker for the metastatic cells is required. We have previously described the enrichment of soybean agglutinin binding cells in tumor populations enriched for lymphatic metastasis [1]. In this study we provide evidence that the cell-surface structure binding soybean agglutinin is a neutral glycosphingolipid. Using monoclonal antibodies generated against this glycolipid, highly metastatic tumor populations were depleted of cells containing this glycolipid. These depleted cell populations were found to be equally tumorigenic to that of the untreated population but were much less metastatic. These results suggest that this glycolipid may be a useful marker for metastatic cells.

Analysis of differentiation and transformation of cells by lectins

During differentiation cells are known to change their biological behavior according to their genotype. This is thought to be accompanied by a modulation of cell surface determinants expressed on the outer cell membrane. Vice versa, cell surface molecules are suggested to mediate extracellular signals to the genome. Most of these molecules integrated in the cell membrane have been proven to be glycoconjugates. The carbohydrate moieties of these molecules can be detected by means of lectins that are characterized by their ability to react specifically with distinct terminal sugar sequences. Thus, lectins have been used as appropriate tools for studying the modulation of functionally important membrane-associated molecules during the differentiation of cells, in particular of B- and T-lymphocytes. Moreover, lectins have been proven to distinguish between differentiated cells and malignant cell clones, according to the hypothesis that transformed cells possess a glycoconjugate profile that corresponds to the stage of differentiation at which they are arrested. Since lectins, like monoclonal antibodies, make it possible to study functionally important molecules that are associated with differentiation and malignancy, they might be of value for diagnostic purposes and, moreover, for analyzing malignant transformation.

Immunohistochemical studies of blood group substance H in colorectal tumors using a monoclonal antibody

With the use of a murine monoclonal antibody with specificity for human blood group substance H, the distribution of this antigen on colorectal carcinomas and adenomatous polyps has been studied by immunohistochemistry. All of the 20 carcinomas studied were found to express H substance regardless of their location in the colon, their pathologic grade, or their clinical stage. Adenomas were variably positive for H substance, and expression of the antigen appeared to correlate with the degree of dysplasia seen on microscopic examination. Normal colonic mucosa, nonadenomatous polyps, and nonepithelial colonic neoplasms studied failed to express H substance. The results suggest that detection of H substance expression may be useful in the diagnosis of colonic malignancies and dysplastic premalignant lesions.

The distribution of blood group antigens in experimentally produced carcinomas of rat palate

It has been shown previously that rat oral epithelia express antigens cross-reacting with antibodies against human blood group antigen B and its structural precursor, the H antigen (Type 2 chain). In the present study we investigated the expression of these antigens in malignant changes in the rat palate induced by a chemical carcinogen (4NQO). The H antigen, normally expressed on spinous cells in rats, was absent in malignant epithelium, whereas staining for the B antigen, normally expressed on basal cells, was variable. These changes are equivalent to those seen in human squamous cell carcinomas. The blood group antigen staining pattern in experimentally produced verrucous carcinomas showed an almost normal blood group antigen expression. This may have diagnostic significance. Localized areas of hyperplastic palatal epithelium with slight dysplasia revealed loss of H antigen and the presence of B antigen in suprabasal strata equivalent to the pattern seen in human premalignant epithelium. We conclude from these findings, that the rat model is well suited to study changes in cell surface carbohydrates during chemical carcinogenesis.

Specific isolation of surface glycoproteins from intact cells by biotinylated concanavalin A and immobilized streptavidin

An indirect affinity chromatography procedure utilizing biotinylated lectins and designed for the specific isolation of surface glycoproteins is described. The method is illustrated with intact acute leukemic lymphoblastic cells (ALL cells) with biotin-epsilon-aminocaproyl-concanavalin A (biocap-Con A) and streptavidin-Sepharose 4B. Biocap-Con A, containing on average 27 biotin residues per tetrameric lectin molecule, is used to isolate Con A-binding glycoproteins from the surface of [35S]methionine-radiolabeled intact cells. The biocap-Con A/glycoprotein complexes, after solubilization in detergent, are retrieved on immobilized streptavidin. The surface glycoproteins isolated from intact ALL cells by this method are subjected to two-dimensional gel electrophoresis and detected by autoradiography. More than fifty Con A-binding glycoproteins can be separated from the ALL cells. These glycoproteins retrievable from the cell surface were compared to those retrieved by the indirect affinity chromatography procedure from isolated plasma membrane fractions. Certain groups of glycoproteins present in the fraction isolated from intact cells were not detected in that from the plasma membrane preparations. The advantage of using the biocap-con A/streptavidin system with intact cells rather than isolated plasma membranes for the detection of surface glycoproteins is discussed.

Demonstration by monoclonal antibodies that carbohydrate structures of glycoproteins and glycolipids are onco-developmental antigens

The hope that hybridoma antibodies would reveal unique cell surface antigens during embryogenesis, differentiation and oncogenesis has been replaced by the realization that such antigens are mainly carbohydrate structures of glycoproteins and glycolipids occurring in many cell types. These findings either may reflect limitations in the methods of selection of hybridoma antibodies or may point to important roles for the diverse carbohydrate structures as receptors for regulators of cell growth and differentiation.

Estimation of ABO(H) isoantigen expression in bladder tumors

ABO(H) isoantigen expression was estimated semiquantitatively with the red cell adherence test on single epithelial cell suspensions from 89 bladder tumor and 7 normal bladder specimens. Correlations of red cell adherence counts positive for antigen with the pathological findings of the bladder (histology and stage of tumor) were made in a blind fashion at the end of the study. The mean count positive for antigen from normal bladders was 86.0, which was significantly different (p less than 0.001) from those of muscle-invading lesions (12.6) and flat carcinoma in situ (21.6). This study shows a good correlation among the cell counts positive for antigen, histological findings and stage of disease, and provides the basis for a prospective study that may help to determine the role of ABO(H) isoantigen measurement in bladder tumor patients.

Structural characterization of glycosphingolipids by direct chemical ionization mass spectrometry

This report describes the use of direct chemical ionization mass spectrometry with ammonia as the reagent gas (NH3-DCI) for structure analysis of underivatized, permethylated and permethylated and reduced glycosphingolipids. In contrast to ionization by electron impact, the NH3-DCI mass spectra exhibit intense molecular and carbohydrate sequence-related ions using microgram amounts of sample. Underivatized glycosphingolipids with up to two sugar residues yield abundant protonated and ammonia-cationized molecular ions and structurally significant fragments. Permethylation in conjunction with NH3-DCI can be used to obtain molecular weight as well as oligosaccharide sequence and branching information on neutral, acidic and complex-type glycosphingolipids with up to five sugar residues. Reduction of the permethylated derivatives gives rise to several new, structurally significant fragments in the corresponding NH3-DCI mass spectra which enable fatty acid and base compositions to be determined. Isotopically labeled reagent gases have been used to confirm the assignment of fragment structures and to demonstrate that the ions observed are unique to the NH3-DCI mass spectra.

Peanut lectin and anti-Ii antibodies reveal structural differences among human gastrointestinal glycoproteins

Human gastrointestinal glycoproteins (mucins), isolated by pepsin digestion from foetal stomachs and meconia, and from paired tumour and non-neoplastic mucosal samples of patients with gastric and colorectal carcinomas, were tested for precipitating reactions with peanut lectin (PNL) and four anti-carbohydrate antibodies (two anti-I, Ma and Low, and two anti-i, Den and Galli). There was remarkable correlation between reactivities with PNL and anti-I (Ma): both reagents reacted with non-neoplastic gastric glycoproteins of "non-secretors", but not with those of "secretors", and also with the majority of gastric tumour and meconium extracts regardless of secretor status. Colorectal tissue extracts (with the exception of one tumour extract) reacted with neither reagent. The various precipitating activities, and results of mild acid hydrolysis and affinity chromatography experiments, enable certain inferences to be made regarding the oligosaccharide moieties of gastrointestinal glycoproteins: (a) expression of PNL and anti-I (Ma) determinants in gastric glycoproteins is dependent on secretor status; (b) extracts reacting with PNL and anti-I (Ma) are mixtures of macromolecules: minor populations react with both reagents, or with PNL only; the major population lacks both determinants, or they are masked by other substitutions; (c) determinants reactive with anti-Ii sera other than anti-I (Ma) are less frequently expressed; and (d) colonic glycoproteins in their lack of PNL and Ii determinants. This suggests that there are structural differences in the oligosaccharide backbones of the two types of glycoprotein.

Marker of peripheral blood granulocytes and monocytes of man recognized by two monoclonal antibodies VEP8 and VEP9 involves the trisaccharide 3-fucosyl-N-acetyllactosamine

Two hybridoma antibodies (VEP8 and VEP9) raised against the promyelomonocytic leukemia cell line HL60 have previously been shown to distinguish human granulocytes and monocytes from other cells of the peripheral blood. We report here that both antibodies recognize the carbohydrate structure 3-fucosyl-N-acetyllactosamine with the following sequence: (formula; see text) This structure is the same as that recognized by a hybridoma antibody against mouse teratocarcinoma cells (anti-SSEA-1) which recognizes an early embryonic antigen in the mouse. Until recently this carbohydrate structure was considered to be rare among glycoproteins and glycosphingolipids. However, there is a growing list of human and animal glycoproteins in which this sequence has been detected by chemical and immunochemical methods. In this article we survey this information and discuss how this and other carbohydrate structures behave as differentiation- or tumor-associated antigens.

Differences of glycoconjugates exposed on hypernephroma and normal kidney cells

We analyzed the outer cell membranes of normal kidney cells, hypernephroma cells, nude mouse transplants of hypernephroma tissue, and cell lines derived from hypernephroma using horseradish peroxidase-coupled lectins of different specificity, in order to investigate their binding to cryostat sections or the cell surfaces of suspended single cells. We showed that hypernephroma cells express higher amounts of receptors for Robinia pseudoacacia lectin, soy bean lectin and Phaseolus vulgaris lectin compared to those prepared from normal kidneys. In contrast, Helix pomatia lectin is bound to connective tissue elements of both malignant and non-malignant tissue exclusively. L-fucose and D-galactose residues are detectable on malignant cells, but not on their non-malignant counterparts. However, the expression of the latter varies considerably among cells from different hypernephromas. No significant difference could be demonstrated between hypernephroma, hypernephroma cell lines and hypernephroma transplants in regard to the carbohydrate profile on the cell surfaces.

Therapy of mouse lymphoma with monoclonal antibodies to glycolipid: selection of low antigenic variants in vivo

Growth of mouse lymphoma L5178Y, which contains large quantitites of the gangliotriosylceramide (GgOs3Cer), in DBA/2 mice was suppressed by passive immunization with monoclonal immunoglobulin G3 antibodies to GgOS3Cer, but not by immunoglobulin M antibodies with or without added complement. Most groups of mice treated with monoclonal immunoglobulin G3 antibodies did not develop tumors, but the tumor that appeared in a treated animal had a much lower amount of the GgOS3Cer than the cells used for inoculation. Thus, passive immunization either prevented growth of the lymphoma or caused selection of a variant with a lower quantity of the antigen GgOS3Cer.