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Detection of medulloblastoma and astrocytoma-associated ganglioside GD3 in cerebrospinal fluid.

Shedding of gangliosides by tumor cells may enhance tumor development. We recently showed that cells of the human brain tumor, medulloblastoma, shed gangliosides in vitro and have therefore examined ganglioside shedding by pediatric brain tumors into the cerebrospinal fluid (CSF). GD3, a major ganglioside in medulloblastoma and astrocytoma, was the target for detection in the CSF by immunostaining using the monoclonal antibody R24 and enhanced chemiluminescence detection. Mean CSF GD3 levels in patients with medulloblastomas (n = 9) and astrocytomas (n = 10) were significantly higher than those of controls (mean +/- SD 44.7 +/- 8.4 versus 18.2 +/- 1.9 pmol/ml, n = 20, P < 0.0002). Mass spectrometric analysis showed that tumor-derived ganglioside GD3 contained heterogeneous ceramide structures and, interestingly, the ceramide subspecies with shorter fatty acyl chains were selectively shed. The elevated CSF GD3 concentrations in patients with medulloblastoma and astrocytoma support the concept that ganglioside shedding, which may have significant biological consequences, is characteristic of human brain tumors.

Astrocytoma↗

Expression of c-series gangliosides in rat hepatocytes and liver tissues.

C-series gangliosides in rat hepatocytes and liver tissues were analyzed by thin-layer chromatographic (TLC) immunostaining with the specific monoclonal antibody A2B5. Primary cultures of hepatocytes isolated from adult rats were immunostained positively by A2B5. TLC immunostaining with A2B5 of gangliosides from the cells suggested that rat hepatocytes express c-series gangliosides including GT3, GT1c, GQ1c, and GP1c. Expression of c-series gangliosides in cultured hepatocytes was modulated by growth conditions of cells. The amount of GT3 was increased significantly by epidermal growth factor, while the contents of polysialo species such as GT1c, GQ1c, and GP1c were enhanced by higher cell density in culture. Examination of c-series gangliosides in rat liver tissues showed a unique developmental profile with a shift from GT3-dominant to polysialo species-dominant composition in late embryonic stages. These results suggest that the expression of c-series gangliosides in rat hepatocytes is regulated in a growth- and development-dependent manner.

Age Factors↗

Gangliosides and sulphatide in human cerebrospinal fluid: quantitation with immunoaffinity techniques.

A sensitive micromethod involving extraction, purification and thin-layer chromatography (TLC)-enzyme immunostaining was developed for the quantation of gangliosides and sulphatide, as markers for neuronal disorders and myelin disturbances, in individual samples of less than 5 ml of cerebrospinal fluid. The gangliosides of the gangliotetraose series were individually determined with cholera toxin subunit B by TLC-enzyme-linked immunosorbent assay (ELISA) after chromatography and subsequent sialidase hydrolysis to II3NeuAc-GgOse4Cer (GM1). Other gangliosides and sulphatide were determined with specific monoclonal antibodies by TLC-ELISA. The total ganglioside content varied between 100 and 230 nmol/l in ten normal cerebrospinal fluid samples from adults. The major gangliosides were of the gangliotetraose series, represented by GM1, IV3NeuAc,II3NeuAc-GgOse4Cer, (GD1a), II3(NeuAc)2-GgOse4Cer (GD1b) and IV3NeuAc,II3 (NeuAc)2-GgOse4Cer (GT1b) of which the b-series gangliosides dominated, i.e., GD1b and GT1b.

Adult↗

Occurrence and tissue distribution of c-series gangliosides in the common squid Todarodes pacificus.

We have recently demonstrated that the common squid Todarodes pacificus express acidic lipids that were reactive with a monoclonal antibody A2B5. In the present study, two A2B5-reactive acidic lipids were isolated from squid hepatopancreatic tissue and characterized for their structures by methods including glycolipid overlay analysis, product analysis after sialidase treatment, and electrospray ionization-mass spectrometry (ESI-MS). Accordingly, the two acidic lipid were identified as GT3 and GQ1c, respectively. Another A2B5-reactive acidic lipid in the tissue was tentatively assigned to GT2 based upon its reactivity to A2B5 and chromatographic mobility on thin-layer chromatography. The composition and concentration of c-series gangliosides significantly differed among squid tissues (i.e. hepatopancreas, cerebral ganglion, eye lens, and mantle tissue). Interestingly, the percentages of c-series gangliosides within total gangliosides of hepatopancreas and cerebral ganglion were even higher than that of cod fish brain, which is known to be highly enriched with this ganglioside species. These findings strongly support the hypothesis that c-series gangliosides in squid tissues are not derived from ganglioside-containing food intake, but biosynthesized in a tissue-specific manner.

Animals↗

Evidence for the existence of ganglioside molecules on Pneumocystis carinii from human lungs.

This study was undertaken to assess whether glycolipid antigens (particularly gangliosides) are associated with Pneumocystis carinii obtained from human lungs. Gangliosides were extracted, purified in high performance thin-layer chromatography and stained with resorcinol. Two resorcinol-positive bands, co-migrating with GM1 and GD1a were demonstrated, suggesting the existence of ganglioside molecules on P. carinii. No resorcinol-positive bands were revealed in the pulmonary control tissue. In addition, an antiserum obtained from rabbits immunized with P. carinii antigen reacted with gangliosides GM1 and GD1a, as revealed by a dot immunobinding assay. This reactivity was inhibited by first incubating the antiserum with ganglioside micelles. Furthermore, anti-glycosphingolipid antibodies (aGM1) reacted with the bands of 200 and 55 kDa of P. carinii antigen. These results suggest that ganglioside antigens expressed on P. carinii can trigger specific immune responses.

Acquired Immunodeficiency Syndrome↗

Dietary lipids containing gangliosides reduce Giardia muris infection in vivo and survival of Giardia lamblia trophozoites in vitro.

We examined whether a ganglioside supplemented diet affected the course of Giardia muris infection in mice and survival of Giardia lamblia trophozoites in vitro. Female CD-1 mice were fed 1 of 5 experimental diets: standard lab chow as a control diet; semi-synthetic diets containing 20% (w/w) triglyceride based on the fat composition of a conventional infant formula; triglyceride diet; triglyceride diet containing a low level of ganglioside (0.1% w/w); and triglyceride diet containing a high level of ganglioside (1.0% w/w of diet). After 2 weeks of feeding, mice were inoculated with G. muris by gastric intubation and fed the experimental diets during the course of the infection. Cysts released in the faeces and trophozoites present in the small intestine were enumerated at various times post-infection. The average cyst output and the number of trophozoites during the course of the infection in mice fed ganglioside-containing diet were found to be significantly lower (3-log10 reduction) compared to animals fed control diets. The results of in vitro growth studies indicated that gangliosides may be directly toxic to the parasites. Thus, gangliosides have a protective effect against G. muris infection in vivo and affect the survival of G. lamblia trophozoites in vitro.

Animals↗

An assay of ganglioside using fluorescence image analysis on a thin-layer chromatography plate.

A new and simple fluorometric method for determine quantities of gangliosides ranging from pico- to nanomoles is reported. Spraying hydrochloric acid followed by a heating treatment, sugars (glucose, galactose, fucose, N-acetylgalactosamine, N-acetylglucosamine, N-acetylneuraminic acid (sialic acid)), gangliosides (G(M1), G(D1a), G(T1b)), and asialoganglioside (asialoG(M1)) on thin-layer chromatography plates produced fluorescence under 365-nm UV light. This fluorescence production of each sample was greatly dependent on the heating temperature. As sialic acid fluoresced readily at lower temperature (approximately 90 degrees C), we were able to distinguish sialic acid easily from other sugars tested. To determine gangliosides based on this sialic acid fluorescence, calibration curves for gangliosides were obtained by high-performance thin-layer chromatography and the image-analyzing system equipped with a CCD camera. The observed fluorescence images were analyzed using image-analyzing software packages and the determined calibration curves for ganglioside-bound sialic acids were reproducible and showed a high linearity in a wide range from 47 pmol to 4.5 nmol. Since the fluorescence from sialic acid is easily measurable on TLC plates and is sensitive over a wide range of sample concentration, the present method is applicable for quantitative determination of gangliosides.

Animals↗

The role of the ganglioside GD1a as a receptor for Sendai virus.

The ganglioside GD1a, which serves as a receptor for Sendai virus, also affects lipid polymorphism as determined by 31P nuclear magnetic resonance. The ganglioside promotes the formation of isotropic structures in monomethyldioleoylphosphatidylethanolamine. GD1a also raises the bilayer to hexagonal phase transition temperature of this lipid. The effects of GD1a on the kinetics of viral fusion can be understood on the basis of its role in facilitating the binding of Sendai virus to target membranes as well as its effects on membrane physical properties. Fusion of Sendai virus with liposomes composed of egg phosphatidylethanolamine is particularly sensitive to the presence of ganglioside. In the absence of ganglioside no fusion is observed due to the absence of virus binding to the target membrane. Between 2 and 6 mol % GD1a in egg phosphatidylethanolamine liposomes there is a marked increase in the rate constant of binding of the virus to the liposome but a decrease in the fusion rate constant. The latter effect is found to be common to a number of other amphiphiles that raise the bilayer to hexagonal phase transition temperature. The ganglioside enhances virus binding to liposomes of all the compositions studied, but leakage rates and fusion rate constants are either unaffected or reduced. In the systems studied, the enhanced formation of isotropic structures in liposomes containing the ganglioside does not enhance the kinetics of the actual fusion reaction.

Gangliosides↗

Immunosuppressive activity of chemically synthesized gangliosides.

New chemical synthetic methods have permitted the synthesis of a spectrum of glycosphingolipid molecular species, some of which are not naturally occurring. Here we have studied a number of chemically synthesized gangliosides for immunosuppressive activity, using a human in vitro specific antigen (tetanus toxoid)-induced assay of the cellular immune response. Chemically synthesized GM3 and GM4 had the same high degree of immunosuppressive activity as did natural GM3 and GM4 gangliosides, verifying that inhibition is intrinsic to the ganglioside molecules and not caused by other molecules sometimes found in natural preparations (e.g., proteins). Studies of modified molecular species of GM3 and GM4, also prepared by chemical synthesis, have shown the influence of certain structural details upon the immunosuppressive activity of gangliosides: (i) the inverse relationship between fatty acyl chain length and immunosuppressive activity is extended to even shorter chain lengths, with the synthetic gangliosides d18:1-C2:0-GM3 and d18:1-C14:0-GM3 being more immunosuppressive than d18:1-C18:0-GM3 and d18:1-C24:0-GM3; (ii) hydroxylation of the fatty acyl group decreases immunosuppressive activity; (iii) substitution of an S-glycosidic bond for an O-glycosidic bond in the sialic acid ketosidic linkage in GM4 does not alter its activity; and (iv) modifications of the sialic acid group variably influence immunosuppressive activity, since KDN-GM3 and -GM4 ganglioside analogues, which contain a 3-deoxy-D-glycero-D-galacto-2-nonulopyranosonic acid in place of N-acetylneuraminic acid, retain activity, while other modifications such as 8-epi-GM3, and to a lesser extent 9-deoxy-GM3, reduce immunosuppressive activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Chemistry↗

Synthesis and characterization of N-parinaroyl analogs of ganglioside GM3 and de-N-acetyl GM3. Interactions with the EGF receptor kinase.

A specific plasma membrane glycosphingolipid, known as ganglioside GM3, can regulate the intrinsic tyrosyl kinase activity of the epidermal growth factor (EGF) receptor; this modulation is not associated with alterations in hormone binding to the receptor. GM3 inhibits EGF receptor tyrosyl kinase activity in detergent micelles, in plasma membrane vesicles, and in whole cells. In addition, immunoaffinity-purified EGF receptor preparations contain ganglioside GM3 (Hanai et al. (1988) J. Biol. Chem. 263, 10915-10921), implying that the glycosphingolipid is intimately associated with the receptor kinase in cell membranes. Both the nature of this association and the molecular mechanism of kinase inhibition remain to be elucidated. In this report, we describe the synthesis of a fluorescent analog of ganglioside GM3, in which the native fatty acid was replaced with trans-parinaric acid. This glycosphingolipid inhibited the receptor kinase activity in a manner similar to that of the native ganglioside. A modified fluorescent glycosphingolipid, N-trans-parinaroyl de-N-acetyl ganglioside GM3, was also prepared. This analog, like the nonfluorescent de-N-acetyl ganglioside GM3, had no effect on receptor kinase activity. Results from tryptophan fluorescence quenching and steady-state anisotropy measurements in membranes containing these fluorescent probes and the human EGF receptor were consistent with the notion that GM3, but not de-N-acetyl GM3, interacts specifically with the receptor in intact membranes.

3T3 Cells↗

Association to HeLa cells and surface behavior of exogenous gangliosides studied with a fluorescent derivative of GM1.

Cultured HeLa cells were incubated with pyrene-GM1/3H-radiolabeled GM1 ganglioside (1:4 M/M) mixtures for various times. The process of association of pyrene-GM1 with cells was qualitatively and quantitatively the same as that of 3H-GM1. The pyrene-GM1 and 3H-GM1 proportions in the various forms of association with cells were similar to that of the starting ganglioside mixture. After 2-h incubation, the association of ganglioside with cells was well established whereas almost no metabolic processing had occurred. During a 24-h incubation, pyrene- and 3H-GM1 underwent similar metabolic processing and gave rise to catabolic (GM2 and GM3) and anabolic (GD1a) derivatives. Fluorescence spectroscopy experiments carried out with the excimer formation technique on subcellular fractions containing plasma membranes showed that exogenous ganglioside was, in part, associated with the cells in a micellar form removable by trypsin treatment, and in part inserted in a seemingly molecular dispersion. Addition of Ca2+ salts caused aggregation of the ganglioside, as indicated by the increase of the excimer:monomer fluorescence ratio. The phenomenon was Ca2+ concentration dependent (maximum at 10 mM), and subsequent addition of EDTA had no effect. The saccharide portion of exogenously incorporated pyrene-GM1 was available to interact with external ligands, as shown by its ability to bind cholera toxin whose addition reduced the collision rate among the ganglioside lipid moieties.

Calcium↗

Recognition characteristics of monoclonal antibodies that are cross-reactive with gangliosides and lipooligosaccharide from Campylobacter jejuni strains associated with Guillain-Barré and Fisher syndromes.

The enteropathogen Campylobacter jejuni has the ability to synthesize glycan structures that are similar to mammalian gangliosides within the core component of its lipooligosaccharide (LOS). Exposure to ganglioside mimics in some individuals results in the production of autoantibodies that deleteriously attack nerve surface gangliosides, precipitating the onset of Guillain-Barré and Fisher syndromes (GBS and FS). We have characterized the interaction of four monoclonal antibodies (mAbs), established by sensitization of mice with LOS isolated from GBS- and FS-associated C. jejuni strains, with chemoenzymatically synthesized gangliooligosaccharides. Surface plasmon resonance (SPR) measurements demonstrate that three of the mAbs interact specifically with derivatives corresponding to their targeted gangliosides, with dissociation constants ranging from 10 to 20 microM. Antibody binding to the gangliooligosaccharides was probed by saturation transfer difference (STD) NMR spectroscopy. STD signals, resulting from antibody/oligosaccharide interaction, were observed for each of the four mAbs. In two cases, differential saturation transfer rates to oligosaccharide resonances enabled detailed epitope mapping. The binding of GD1a-S-Phe with GB1 is characterized by close association of the immunoglobulin with sites that are distributed over several residues of the oligosaccharide. This contrasts sharply with the profile observed for the binding of both GD3-S-Phe and GT1a-S-Phe with FS1. The close antigenic contacts in these ganglioside derivatives are confined to the N-acetylmannosaminyl portion of the terminal N-acetylneuraminic acid (NeuAc) residue of the disialosyl moiety. Our characterization of FS1 provides insight, at an atomic level, into how a single antigenic determinant presented by the LOS of C. jejuni can give rise to antibodies with binding promiscuity to [alphaNeuAc-(2-8)-alphaNeuAc]-bound epitopes and demonstrates why sera from FS patients have antibodies that are often reactive with more than one disialylated ganglioside.

Animals↗

Alteration of ganglioside composition by stable transfection with antisense vectors against GD3-synthase gene expression.

Gangliosides are ubiquitous components of mammalian cells. Their expression is frequently altered in many tumor types. We previously showed that alteration of the ganglioside composition often resulted in changes in cellular morphology and differentiation of cultured cells. In this study, we targeted sialyltransferase gene expression by the antisense knockdown experiment, and the results showed that inhibition of the expression of gangliosides GD3 and O-acetylated GD3 (OAc-GD3) in the neuroblastoma F-11 cells greatly reduced the tumor growth in nude mice. The sense and antisense vectors containing either a 5' end fragment or the entire sequence of the cDNA coding for GD3-synthase were prepared and used in separate experiments to transfect the F-11 cells which express high levels of gangliosides GD3 and OAc-GD3. Single clones were isolated and expanded. Both the activity of the GD3-synthase and the concentrations of GD3 and OAc-GD3 in the antisense-transfected cells were dramatically decreased as a result of transfection with the antisense expression vectors. Further characterization of the antisense-transfected cells showed reduced rates of cell growth and neurite formation and changes in cellular morphology. When the cells were inoculated in athymic nude mice, the tumor growth rate was remarkably suppressed although the tumor incidence was not affected by the altered ganglioside composition. These results indicate that the tumor-associated ganglioside(s) is(are) involved in regulation of tumor growth, probably through the stimulation of angiogenesis of the tumor.

Animals↗

Deletion of complex gangliosides of human glioma cells during mitotic cell division.

Glycolipid compositions of the human glioma cell line T98G were studied during each phase of the cell cycle to see if those cell surface molecules are concerned with cell proliferation. In vitro cultured non-synchronized T98G cells are composed of ceramidemonohexoside (CMH), ceramidedihexoside (CDH), ceramidetrihexoside (CTH) and neolactotetraosylceramide (nLc4Cer) as neutral glycolipids, and of sulfatide (CS), gangliosides GM3, GM2, GD1a and several other gangliosides as acidic ones. While total glycolipid content per cellular weight was shown to be increased during the M phase, deletion of complex gangliosides particularly b-series gangliosides was recognized (p < 0.05). The glycolipid profile in other phases was fairly consistent, and there was no glycolipid molecule specific to a certain phase of the cell cycle. Relative enhancement of simple gangliosides with a decrease of complex ones during mitotic division may imply the functional involvement of complex gangliosides in cell-cell or cell-matrix attachment, which may have to be abandoned during the process of detachment from the matrix or cellular cleavage.

Cell Division↗

Ganglioside function in calcium homeostasis and signaling.

Ganglioside function in eukaryotic cells encompasses a variety of modulatory interactions related to both development and mature cellular behavior. In relation to the nervous system this includes induction of neurite outgrowth and trophic/neuroprotective phenomena; more generally this applies to ganglioside effects on receptor function, adhesion reactions, and signal transduction mechanisms in neural and extraneural systems. Underlying many of these trophic effects are ganglioside-induced changes in cellular calcium, accomplished through modulation of Ca2+ influx channels, Ca2+ exchange proteins, and various Ca2+-dependent enzymes that are altered through association with gangliosides. A clear distinction needs to be drawn between intrinsic functions of gangliosides as naturally expressed by the cell and activities created by application of exogenous ganglioside(s) that may or may not reflect natural function. This review attempts to summarize findings in this area and point to possible future directions of research.

Animals↗

Uptake of exogenous gangliosides by rat brain synaptosomes.

Synaptosomes incorporated mixed brain gangliosides at a rapid initial rate followed by a slower phase of net movement from the protein-associated fraction into the membrane core. The pattern of incorporated gangliosides reflected the pattern available for incorporation. Intact synaptosomes incorporated approximately 100 pmol GM1/mg protein. Synaptosomes preincubated with proteolytic enzymes (trypsin, chymotrypsin, and papain) at different pH values (6.2, 7.4, 7.8) incorporated more exogenous gangliosides than synaptosomes preincubated in buffer alone. This effect was maximal at pH 7.8, though analysis of variance revealed that the proteolytic treatment and pH effects were probably independent processes. Overall uptake of exogenous gangliosides correlated significantly with amount of membrane protein loss, indicating that initial access of exogenous gangliosides to synaptosomal membranes is retarded by cell-surface proteins. These results suggest synaptosomes as a useful alternative to cultured cells for investigating the interaction of gangliosides with other cell surface constituents.

Animals↗

1H NMR ganglioside ceramide resonance region on the differential diagnosis of low and high malignancy of brain gliomas.

1. The high-resolution 1H NMR (MRS) spectra of human brain tumor homogenates revealed a broad resonance at 5.3-5.4 ppm in glioblastoma multiforme (N = 16) and brain metastases (N = 3). The broad resonance was identified as ceramide, a sphingosine-fatty acid combination portion of ganglioside, indicating an elevated abundance of monounsaturated fatty acids. GLC analysis of gangliosides in the highly malignant glioblastoma multiforme revealed that the elevated monounsaturated fatty acid is oleic acid (C18:1). The resonance at 5.3-5.4 ppm region was not detectable in normal human brain (N = 2), in meningiomas (N = 2), or in low-grade astrocytomas (N = 12). In normal human brain the abundance of monounsaturated fatty acid is minimal. 2. This investigation was made possible because the method of producing homogenate resulted in (i) no loss of lipids during the process and (ii) a well-homogenised sample, with (iii) no loss in chemical integrity. 3. The properties of tumor gangliosides include antigenic specificity and immunosuppressive activity and the ceramide, a sphingosine-fatty acid combination, noticeably influences the ganglioside immunosuppressive activity. 4. The observation of 1H NMR ceramide resonance in high-malignant brain tumors emphasizes the dramatic role of aberant gangliosides and ceramide precursors on the grade of malignancy and invasiveness. 5. Further insight into the specific nature of the ceramide portion of gangliosides in grading the malignancy of brain tumors should be investigated further.

Astrocytoma↗

The gangliosides as a possible molecular coupling factor between the proportion of radiosensitive cells in vitro and the metastatic potential in vivo within a human melanoma cell line.

With an experimental model of spontaneous lung metastases in immunosuppressed newborn rats, seven clones and variants with different metastatic potential and gangliosides expression were derived from a single parental human melanoma cell line M4Be. The cellular radiosensitivity of M4Be and its seven sublines was estimated using an in vitro colony assay. The total amount of gangliosides in M4Be and its seven sublines was determined by cell extraction and thin-layer chromatography, while the expression of GD3 gangliosides was estimated by flow cytometry with a monoclonal antibody. The radiation-cell survival curves of most clones and variants derived from M4Be showed a zero dose extrapolation clearly lower than 100%, suggesting that two populations of cells of very different radiosensitivity coexist within each of these clones and variants. Although the proportion of radiosensitive cells could be estimated from the shape of the survival curve, its radiosensitivity is too high to be properly evaluated by the colony assay. The eight survival curves differ essentially in the proportion of radiosensitive cells--which varied from 0% to 40% among M4Be and its seven sublines--whereas the cellular radiosensitivity of the radioresistant population was similar among them. The metastatic potential in vivo of M4Be and its seven sublines was not significantly related to the cellular radiosensitivity of their corresponding radioresistant population, but significantly increased with the fraction of radiosensitive cells. This relationship is valid only when the highly metastatic cells are cultured for no more than five passages in vitro as the fraction of radiosensitive cells is rapidly lost during subcultures. The relationship remains valid in vivo as metastatic melanoma-bearing newborn rats whole body irradiated with 20 cGy show no lung metastasis compared with controls. The radiosensitive cell fraction is inversely correlated with both the total ganglioside content (r = 0.84, P < 0.02) and the number of cells positively labelled with the monoclonal antibody directed to GD3 (r = 0.92, P < 0.001). The incubation of a radiosensitive clone with the exogenous bovine brain ganglioside GM1 significantly increases the proportion of radioresistant cells and suppresses its metastatic potential, while the inhibition of the endogenous gangliosides synthesis in the radioresistant cell line M4Be increases the proportion of radiosensitive cells. This study provides a possible explanation for the correlation between the metastatic potential and the proportion of radiosensitive cells within the seven sublines derived from a single parental human melanoma cell line.

Animals↗