g(m2)-ganglioside and Glioma

The frequently occurring alteration of ganglioside expression in tumor cells has been implicated to play a role in the uncontrolled growth of these cells; antibodies to such gangliosides might affect tumor cell growth. We have studied the effect of IgM monoclonal antibodies to two glioma-associated gangliosides, GD3 and GM2, on cell proliferation of four human glioma cell lines and one renal tumor cell line. Of the two anti-ganglioside antibodies tested, only the anti-GD3 antibody resulted in a significant (p<0.005) inhibition of cell proliferation as measured by thymidine incorporation and Brd-U labeling, after 24h incubation. The effect was not dependent on any serum factor and no increased cell death was observed. All cell lines contained higher or similar amounts of GM2 than GD3, and both antigens were shown to be expressed on the cell surface and accessible to antibodies. The selective effect of anti-GD3 antibodies as contrasted to the inactivity of anti-GM2 antibodies suggests a possible role for ganglioside GD3 in tumor cell proliferation.

Topics: Antibodies, Monoclonal; Cell Division; Central Nervous System Neoplasms; Drug Screening Assays, Antitumor; G(M2) Ganglioside; Gangliosides; Glioma; Humans; Necrosis; Thymidine; Tumor Cells, Cultured

Ganglioside sialic acid content was examined in the U87-MG human glioma grown as cultured cells and as a xenograft in severe combined immunodeficiency (SCID) mice. The cultured cells and the xenograft possessed N-glycolylneuraminic acid (NeuGc)-containing gangliosides, despite the inability of human cells to synthesize NeuGc. Human cells express only N-acetylneuraminic acid (NeuAc)-containing gangliosides, whereas mouse cells express both NeuAc- and NeuGc-containing gangliosides. Small amounts of NeuGc ganglioside sialic acid (2-3% of total ganglioside sialic acid) were detected in the cultured cells, whereas large amounts (66% of total ganglioside sialic acid) were detected in the xenograft. The NeuGc in gangliosides of the cultured cells was derived from gangliosides in the fetal bovine serum of the culture medium, whereas that in the U87-MG xenograft was derived from gangliosides of the SCID host. The chromatographic distribution of U87-MG gangliosides differed markedly between the in vitro and in vivo growth environments. The neutral glycosphingolipids in the U87-MG cells consisted largely of glucosylceramide, galactosylceramide, and lactosylceramide, and their distribution also differed in the two growth environments. Asialo-GM1 (Gg4Cer) was not present in the cultured tumor cells but was expressed in the xenograft, suggesting an origin from infiltrating cells (macrophages) from the SCID host. The infiltration of mouse host cells and the expression of mouse sialic acid on human tumor cell glycoconjugates may alter the biochemical and immunogenic properties of xenografts.

Topics: Animals; G(M2) Ganglioside; G(M3) Ganglioside; Gangliosides; Glioma; Humans; Mice; Mice, Inbred C57BL; Mice, SCID; N-Acetylneuraminic Acid; Neoplasm Transplantation; Neuraminic Acids; Transplantation, Heterologous; Tumor Cells, Cultured

The human glioma D-54MG cell line grown in vitro primarily expresses ganglio series gangliosides, particularly GM2. Subcutaneous injection of these cells into nude mice produced xenografts with an increased content of the human glioma-associated lacto series gangliosides, primarily 3'-isoLM1, an alteration that was dose dependent, with the highest dose (1 x 10(8)) resulting in a phenotype that was most like that of the inoculum. After one passage in vivo, the lacto series dominated and reached a proportional level that was kept throughout the 10 passages. The mRNA levels of the GM2-synthase clearly coincided with GM2 expression and was 20 times higher in cells grown in vitro than in those grown in vivo. These results support the view that ganglioside expression in human gliomas is strongly influenced by environmental factors.

Topics: Animals; Carbohydrate Sequence; Cell Division; Cell Line; Culture Media; G(M2) Ganglioside; Gangliosides; Glioma; Humans; Mice; Mice, Nude; Molecular Sequence Data; N-Acetylgalactosaminyltransferases; Polypeptide N-acetylgalactosaminyltransferase; RNA, Messenger; Spectrometry, Mass, Fast Atom Bombardment; Transcription, Genetic; Transplantation, Heterologous; Tumor Cells, Cultured

C6 rat glioma cells incubated in serum-free medium with D-[14C]glucosamine secrete, on stimulation with nerve growth factor (NGF) or monosialogangliosides (MSGs), several glycoproteins (Gps), the most prominent of which are a 270-, 220-, and 69-kDa Gp. Several growth factors, hormones, phorbol ester, and disialo- and trisialogangliosides did not stimulate secretion. Western blot analysis of the conditioned medium from C6 cells stimulated with NGF or MSG identified one distinct band of approximately 220 kDa for fibronectin and J1/tenascin, which comigrated. Antiserum to NGF prevented NGF-stimulated release and also blocked MSG-evoked release. The 220-kDa band was labeled after pulse labeling with [35S]methionine in the presence of NGF, and by a 15-min chase period radioactively labeled J1/tenascin could be immunoprecipitated. Tunicamycin drastically inhibited almost completely release of the 220-kDa Gp labeled by D-[14C]glucosamine or [35S]methionine. These results extend the range of neurotrophic properties attributed to NGF to cells of glial origin and suggest that NGF regulates secretion of extracellular matrix proteins. MSG stimulation of fibronectin and J1/tenascin secretion may be mediated by NGF or an NGF-like molecule also secreted by the C6 glioma cells.

Topics: Animals; Blood; Blotting, Western; Carbohydrate Sequence; Cell Adhesion Molecules, Neuronal; Extracellular Matrix Proteins; Fibronectins; G(M1) Ganglioside; G(M2) Ganglioside; G(M3) Ganglioside; Gangliosides; Glioma; Glucosamine; Glycoproteins; Glycosylation; Kinetics; Molecular Sequence Data; Molecular Weight; Nerve Growth Factors; Rats; Tenascin; Tumor Cells, Cultured; Tunicamycin

The effects of four anti-GM2 monoclonal antibodies (DMAb-1, DMAb-2, DMAb-3, and DMAb-5) were studied on spheroid cultures from a human glioma cell line (D-54 MG) that is known to express high levels of GM2. The spheroids developed central necrosis 48 h after antibody exposures at concentrations greater than 6 micrograms/ml. No necrosis was found with antibodies that had been absorbed with GM2 prior to exposure or with unrelated cytotoxic antibodies. Immunohistochemistry showed that the necrosis started shortly after the antibodies were evenly distributed throughout the spheroids. Light and transmission electron microscopy revealed that a small portion of the cells, mainly in the periphery of the spheroids, was unaffected by antibody exposure. New monolayer cultures established from antibody-treated cells expressed a 50% lower GM2 content as shown by flow cytometry and determination of ganglioside content throughout at least 12 passages. Thus, the GM2-rich D-54 MG cell line has subpopulations of cells with lower GM2 content. Spheroids obtained from this subpopulation developed only minor necrosis after antibody treatment. These results show that GM2 antibodies cause severe necrosis of GM2-containing glioma cells in vitro, but the effect depends on the concentration of antigen, and a threshold number of GM2 molecules is required.

Topics: Antibodies, Monoclonal; Cell Survival; G(M2) Ganglioside; Glioma; Humans; Microscopy, Electron; Microscopy, Fluorescence; Necrosis; Tumor Cells, Cultured

In order to investigate GM2 expression in gliomas, the GM2-positive human glioma cell line (HGL) D-54 MG, which contains 0.6 nmol GM2/mg protein, representing 77% of the total monosialoganglioside fraction, was used as an immunogen for the production of anti-GM2 monoclonal antibodies. For ganglioside designations, see IUPAC-IUB (Eur. J. Biochem., 79: 11-21, 1977) and Svennerholm (J. Neurochem., 10: 613-623, 1963). Five IgM monoclonal antibodies (DMAb-1 through DMAb-5) specifically recognizing the GalNAc beta1-4(NeuAc alpha 2-3)Gal-terminal epitope common to GM2 and GalNAC-GD1a are reported. The antibodies did not react with GM1, GM3, GD2, GD3, GD1a, GD1b, and GQ1b. Purified anti-GM2 MAbs were used to define the expression of the "GM2" terminal epitope by cultured human malignant and normal cells by radioimmunoassay and membrane immunofluorescence. Among neuroectodermal tissue-derived cell lines, DMAb-3, at an optimal concentration of 5 micrograms/ml, showed high reactivity (radioimmunoassay binding ratios greater than 20) with 9 of 19 HGLs, 3 of 5 medulloblastoma, 4 of 5 neuroblastoma, and 1 of 3 melanoma lines. Moderate reactivity (binding ratio, 10-20) was exhibited by 3 HGL, 2 medulloblastoma, and 1 neuroblastoma lines and low reactivity (binding ratio, 3-10) by 5 HGL lines; no reactivity was detected with 2 HGL and 2 melanoma lines. Densitometric evaluation of monosialoganglioside extracts from human glioma and medulloblastoma cell lines in conjunction with immunostaining on thin-layer chromatograms showed that GM2 represents the major monosialoganglioside in 8 of 10 HGL and in 3 of 4 Med lines. In these lines the amount of GM2 ranged from less than 0.1 to 0.6 nmol/mg protein. These results indicate that GM2 represents a proportionally increased ganglioside of most glioma, medulloblastoma, and neuroblastoma cells in vitro.

Topics: Antibodies, Monoclonal; Antibodies, Neoplasm; Antibody Specificity; Antigens, Neoplasm; Dose-Response Relationship, Immunologic; Epitopes; G(M2) Ganglioside; Gangliosides; Glioma; Humans; Medulloblastoma; Melanoma; Neuroblastoma

The enzymatic basis for ganglioside regulation during differentiation of NG108-15 mouse neuroblastoma x rat glioma hybrid cells was studied. This cell line contains four gangliosides that lie along the same biosynthetic pathway: GM3, GM2, GM1, and GD1a. Chemically induced neuronal differentiation of NG108-15 cells led to an 80% drop in the steady-state level of their major ganglioside, GM3, a sixfold increase in the level of a minor ganglioside, GM2 (which became the predominant ganglioside of differentiated cells); and relatively little change in the levels of GM1 and GD1a, which lie further along the same biosynthetic pathway. The enzymatic basis for this selective change in ganglioside expression was investigated by measuring the activity of two glycosyltransferases involved in ganglioside biosynthesis. UDP-N-acetylgalactosamine: GM3 N-acetylgalactosaminyltransferase (GM2-synthetase) activity increased fivefold during butyrate-induced differentiation, whereas UDP-galactose: GM2 galactosyltransferase (GM1-synthetase) activity decreased to 10% of its control level. Coordinate regulation of these two glycosyltransferases appears to be primarily responsible for the selective increase of GM2 expression during NG108-15 differentiation.

Topics: Alprostadil; Animals; Bucladesine; Cell Differentiation; G(M1) Ganglioside; G(M2) Ganglioside; G(M3) Ganglioside; Galactosyltransferases; Ganglioside Galactosyltransferase; Gangliosides; Glioma; Hybrid Cells; Kinetics; Mass Spectrometry; Mice; N-Acetylgalactosaminyltransferases; Neuroblastoma; Polypeptide N-acetylgalactosaminyltransferase; Rats; Theophylline; Tumor Cells, Cultured

Rat glioma X mouse neuroblastoma hybrid neurotumor cells (NG108-15), synchronized by amino acid deprivation, showed a cell-cycle-dependent peak of activity of a ganglioside N-acetylgalactosaminyl transferase 14-24 h following release from the cell cycle block (S/G2 phase). Maximal expression of two typical lysosomal hydrolases, N-acetyl-beta-hexosaminidase and beta-galactosidase, occurred between 18 and 21 h following release (S phase), declining to G1 phase levels during the peak of N-acetylgalactosamine (GalNAc) transferase activity. In addition, glycosyltransferase activity in G2 phase cells showed an increase in apparent Vmax (suggesting the presence of more enzyme/mg of cell protein) and apparent binding affinity for uridine diphosphate N-acetylgalactosamine (UDP-GalNAc) (32 versus 14 microM) when compared to transferase activity in the G1 phase. However, the opioid peptide enkephalin [D-Ala2, D-Leu5], which inhibits ganglioside GalNAc transferase activity in unsynchronized NG108-15 cultures, was much more inhibitory in whole cells 8 h after release from the cell cycle block (G1 phase) than in cells 20 h after release (G2 phase), with 50% inhibition occurring at 2 X 10(-9) M and 2 X 10(-7) M, respectively. These results suggest that the GalNAc transferase activity is regulated in more than one way during the cell cycle, since both Vmax and Km changes are observed, and that the cyclic AMP-dependent mechanism by which opiates reduce transferase activity is receptor mediated and cell cycle dependent.

Topics: Animals; Cell Cycle; Enkephalin, Leucine; Enkephalin, Leucine-2-Alanine; Enkephalins; G(M2) Ganglioside; G(M3) Ganglioside; Galactosyltransferases; Gangliosides; Glioma; Hybrid Cells; Kinetics; Mice; N-Acetylgalactosaminyltransferases; Neuroblastoma; Rats