Gangliosides as antigens of human melanoma

Multicompartmental Lipopolyplex as Vehicle for Antigens and Genes Delivery in Vaccine Formulations

Vector design and its characterization is an area of great interest in current vaccine research. In this article, we have formulated and characterized a multicompartmental lipopolyplex, which associates multiple liposomes and polyplexes in the same complex. These particles allow the simultaneous delivery of lipid or water-soluble antigens associated with genes to the same cell, in much higher amounts than conventional lipopolyplexes. The vector characterization and optimization were carried out using liposomes with entrapped carboxyfluorescein and adapted electrophoretic assays. Two types of lipopolyplexes (containing hydrophilic or lipophilic antigens) were employed to evaluate their interest in vaccination. The lipopolyplex loaded with an extract of water-soluble melanoma proteins proved to efficiently induce humoral response in murine melanoma model, increasing the levels of IgM and IgG. The specificity of the immune response induced by the lipopolyplex was demonstrated in mice with the lipopolyplex containing the GD3 ganglioside lipid antigen, abundant in melanoma cells. The levels of anti-GD3 IgG increased markedly without modifying the expression of humoral antibodies against other gangliosides.

A New Procedure for Gangliosidic N-Acetylneuraminic Acid Analysis in Serum

In this paper a method is presented which is suitable for the extraction, purification and analysis of serum gangliosides. The advantage in comparison with other previously published procedures is the complete extraction of sialoglycolipids without contamination of sialoglycoproteins and/or sialoglycopeptides. The method could be used as a second-level test for the diagnosis and follow-up of cancer patients, and also could be potentially used for pharmaco-kinetic studies after ganglioside treatment.

Erythroid cells in immunoregulation: characterization of a novel suppressor factor

Nucleated erythroid cells (EC) have been previously reported to possess a potent natural suppressor (NS) activity for B-cell responses. In this study, we demonstrate that murine EC are able to reduce not only lipopolysaccharide (LPS)-driven B-cell proliferation, but also proliferative and cytotoxic T-cell responses generated in a primary allogeneic mixed lymphocyte culture (MLC); and that a soluble low molecular weight factor may be involved in such EC-derived immunoregulation. In addition, the erythroid cell-derived suppressor factor (ESF) was found to be capable of effectively reducing the allergen-driven proliferation of peripheral blood mononuclear cells (PBMC) isolated from allergic patients. From the data presented herein, it appears that ESF is heat-stable (80 degrees C for 20 min) and has molecular weight (MW) lower or close to 0.5 kDa. ESF activity is resistant to both enzyme (trypsin plus chymotrypsin) proteolysis and action of the enzymes such as lipase and phospholipase C. On the other hand, ESF is effectively inactivated by neuraminidase treatment, suggesting the presence in its structure of sialic residue(s). The neuraminidase-sensitive, ESF-like activity is readily detected in the medium conditioned with normal mouse bone marrow (BM) cells. On fractionation of low MW erythroid products on a reversed-phase C16 column in a linear acetonitrile gradient (5-95%), ESF activity is detected in the first peak alone with the shortest time of its retention by the column. The results suggest that (1) by producing ESF, EC may regulate both B- and T-cell-mediated immune processes and (2) based on its physicochemical and biological characteristics, ESF can be distinguished from each of earlier characterised suppressor mediators of bone marrow origin.

The glioma-associated gangliosides 3'-isoLM1, GD3 and GM2 show selective area expression in human glioblastoma xenografts in nude rat brains

This work describes the in vivo expression and distribution of glioma-associated gangliosides (GD3, GM2, 3'-isoLM1) in a novel human brain tumour nude rat xenograft model. In this model, the tumours, which are established directly from human glioblastoma biopsies, show extensive infiltrative growth within the rat brain. This model therefore provides an opportunity to study ganglioside expression not only within the macroscopic tumour, but also in brain areas with tumour cell infiltration. The ganglioside expression was studied by confocal microscopy of immunostained brain sections using antiganglioside monoclonal antibodies. Xenografts from four human glioblastoma multiformes were established in rats and the brains removed after 3-4 months. Ganglioside GD3 was expressed in the tumour parenchyma while ganglioside 3'-isoLM1 was more abundantly expressed in the periphery of the tumour associated with areas of tumour cell invasion. GM2 expression was only seen in one tumour, where it was located within the main tumour mass. Double staining with a pan antihuman monoclonal antibody (3B4) and the antiganglioside monoclonal antibodies confirmed that the ganglioside expression was associated with tumour cells. This work supports the concept of different biological roles for individual gangliosides and indicates that antibodies or ligands directed against GD3 and 3'-isoLM1 might be complementary when applied in the treatment of human glioblastomas.

Polysialogangliosides expressed by amelanotic melanoma: a possible explanation for the poor response to anti-monosialoganglioside antibody 202 in a patient with melanoma

A 52-year-old Japanese woman developed numerous amelanotic metastatic melanomas on the skin and in various organs three years after a surgical operation for primary melanoma on the right axilla. The patient was treated with monosialoganglioside specific monoclonal antibody 202; however, no apparent clinical effects were observed. Ganglioside analysis of a metastatic tumor demonstrated that it expressed GM3, GM2, GD3, GD2, and polysialogangliosides. Since polysialogangliosides rarely appear in melanomas, their expression may explain the patient's poor response to MAb 202. The relationship between ganglioside composition and the effect of anti-ganglioside monoclonal antibody is discussed.

Efficacy of tumor cell vaccine after incorporating monophosphoryl lipid A (MPL) in tumor cell membranes containing tumor-associated ganglioside

Murine B16 melanoma expresses the ganglioside GM3. GM3 shed from tumor cells is immunosuppressive and promotes tumor growth. Reduction or elimination of the shed GM3 could be therapeutic, and the anti-GM3 antibodies may reduce and clear the shed ganglioside. To test this hypothesis, mice were challenged with tumor cells, with or without inducing anti-GM3 antibody response. Since gangliosides are poor immunogens and T-cell independent antigens, an adjuvant (monophosphoryl lipid A (MPL), a non-toxic lipid A of Salmonella), directed against B-cells, was employed. MPL was incorporated onto liposomes and into the surface membrane of B16 mouse melanoma cells; both are rich in GM3. C57BL/6J mice immunized with MPL-liposomes or MPL-B16 cells responded with elevated levels of anti-GM3 IgM. Non-immunized mice or mice immunized with B16 cells alone or ganglioside GM3 alone (without MPL) elicited poor anti-GM3 IgM response, confirming the GM3's immunologic crypticity and MPL's immunopotentiating effect. MPL's immunopotentiating effect was improved by coupling it to melanoma cell membranes. C57BL/6J mice were immunized with irradiated B16 alone or MPL alone or MPL-conjugated irradiated B16. After three weekly immunizations, each mouse received a challenge dose of viable syngeneic B16. Neither MPL alone nor B16 alone had a significant effect on tumor growth or host survival; however, administration of MPL-conjugated B16 cells significantly prevented tumor growth and prolonged survival. Our results indicate that MPL-incorporated B16 cells augment the anti-GM3 IgM response, which may reverse GM3-induced immunosuppression by eliminating tumor-derived GM3, and restore immunocompetence.

Regulation of ganglioside composition and synthesis is different in developing chick retinal pigment epithelium and neural retina

We examined the immunocytochemical expression of GM3 and GD3 in 3-day-old chick embryo retinal pigment epithelium (RPE) and neural retina (NR). We also compared the composition of gangliosides and the activities of key ganglioside glycosyltransferases of the RPE and NR of 8-, 12-, and 15-day old embryos. The immunocytochemical studies in 3-day-old embryos showed heavy expression of GM3 and GD3 at the inner and outer layers of the optic vesicle that are the precursors of the RPE and NR, respectively. The compositional and enzymatic studies showed pronounced differences between RPE and NR of 8-day and older embryos. HPTLC showed that at 8 days the major species were GM3 and GD3 in RPE and GD3 and GT3 in NR. As development proceeded, GD3 decreased in both tissues, GM3 became the major ganglioside in RPE, and ganglio-series gangliosides (mainly GD1a) became the major species in NR. At 15 days the major species were GD1a in NR and GM3 in RPE. Enzyme determinations showed that whereas in RPE from 12-day-old embryos GM2 synthase was under the limit of detection and GD3 synthase activity was about sixfold lower than GM3 synthase, in NR the activities of GM3 and GD3 synthases were similar and both six- to ninefold lower than GM2 synthase. These results evidence a markedly different modulation of the ganglioside glycosylating system in cells of a common origin that through distinct differentiation pathways originate two closely related tissues of the optic system.(ABSTRACT TRUNCATED AT 250 WORDS)

Variations in the ganglioside profile of uveal melanoma correlate with cytologic heterogeneity

Gangliosides may play an important role in the proliferation and spread of human malignant melanoma. Because the frequency of metastases in uveal and cutaneous melanoma differs, it is possible that they may express different gangliosides. We analyzed the ganglioside profiles of primary uveal melanoma in 14 cases and of cutaneous melanoma metastasis in 19 cases. In cutaneous melanoma, GM3 ranged from 4.2% to 74.6% and GD3 from 22.1% to 91.8% of total lipid-bound sialic acid. GM2 (found in 13 of 19 cases, ranging from 0.5% to 11.7%), GD2 (11/19, 0.5%-22.0%) and 9-O-acetyl-GD3 (13/19, 0.5%-12.6%) were also frequently observed. By contrast, in 11 cases of uveal melanoma, GM3 was > 90%, GD3 was < 10%, GM2 was < 1.1%; neither GD2 nor 9-O-acetyl-GD3 were detected. The ganglioside profiles of these uveal melanomas were virtually identical to those of normal melanocytes obtained from foreskins. Histological examination of these 11 biopsies showed a monomorphous cell composition, but neither infiltration of lymphocytes or melanophages nor cell necrosis was observed. In 3 other cases, GD3 was increased to 19.5%-46.0%. Histological examination of these 3 biopsy specimens showed at least 2 populations of tumor cells that were separable based on morphological grounds, and mononuclear inflammatory cells interspersed among the tumor cells. An increase in GD3 appears to be related to tumor polyclonality and infiltration of the tumor by lymphocytes and macrophages. These results suggest that ganglioside expression of uveal melanoma is associated with host immune responses to the tumor. Furthermore, the low metastatic capacity of uveal melanoma, in contrast to the high metastatic rate of cutaneous melanoma, may be a result of its differentiated ganglioside expression, which is strikingly similar to that of normal melanocytes.

An agglutinin with unique specificity for N-glycolyl sialic acid residues of thyroglobulin in the hemolymph of a marine crab Scylla serrata (Forskal)

A novel agglutinin with specificity for sialic acid sequence of sugars in thyroglobulin is identified in the hemolymph of Scylla serrata. The physico-chemical characteristics of its binding affinity, such as pH and temperature optima, and cationic requirements are defined. N-glycolyl neuraminic acid (NeuGc) (at 0.6 mM), in contrast to N-acetyl neuraminic acid (NeuAc) (at greater than 5.0 mM), is the potent inhibitor of hemagglutination. Bovine and porcine thyroglobulins containing NeuGc, inhibited the agglutination. NeuGc-acid glycoprotein fraction (bovine) but not NeuAc-acid glycoprotein fraction (human) inhibited the hemagglutination. The inability of other NeuGc-glycoproteins (bovine submaxillary mucin) to inhibit the agglutination suggests that the agglutinin may also recognize glycosidic linkage associated with NeuGc. The potential of the agglutinin in identifying NeuGc containing human tumor associated antigens is discussed.

Ganglioside GM3:GD3 ratio as an index for the management of melanoma

This report evaluates the relevance of the ratio of the melanoma-associated ganglioside, GD3, and its precursor, GM3, to prognosis and management of Stage II disease. Tumor biopsy specimens from 42 melanoma patients were examined for the ratio and found that GD3 and GM3 constitute 80% of the total lipid bound sialic acids (LBSA) of melanoma. Although the ratio of GM3:GD3 in melanocytes, the progenitors of melanoma, is 19:1 (based on %LBSA), it ranged from 15:1 to 1:5 in tumor biopsy specimens. Patients are categorized into three groups based on their GM3:GD3 ratio (%LBSA) of tumor tissues as Group I (ratio ranged from 15:1 to 1.5:1) (10 of 42), Group II (1.4:1 to 1:1.4) (13 of 42), and Group III (1:1.5 to 1:5) (19 of 42). When the overall survival of patients from the onset of Stage II disease was evaluated among different groups, patients belonging to Group I survived significantly longer than patients of Group II (P = 0.02) and Group III (P = 0.01). Interestingly, Group III expressed immunogenic gangliosides (GD2, GM2, and O-AcGD3) better than the other groups and may benefit more from therapies targeted against these gangliosides antigens. The results of this study indicate that GM3:GD3 ratio is an unusual but well-defined biochemical criteria that may be useful for prognosis and therapeutic management of the disease. Therefore, we propose a routine analysis of the GM3:GD3 ratio of tumors excised after surgery. Screening the ratio is feasible since melanoma expresses a simple profile of gangliosides unlike other forms of cancer.

Gangliosides of human melanoma

Human melanoma synthesizes a large quantity of gangliosides, glycosphingolipids containing sialic acid. The authors previously have demonstrated that the ganglioside profile differs among individual melanomas and is widely heterogeneous. In the current study, a retrospective study was performed to compare the relationship between the quantity of five major gangliosides of human melanoma (GM3, GM2, GD3, GD2, and alkali-labile ganglioside) and nine clinical factors (sex, age, site, stage, tumor size, pigmentation, histopathologic type of primary tumor, chemosensitivity, and prognosis). Melanoma specimens studied were obtained from patients of our clinic and included 52 biopsy specimens and 28 cultured cell lines. Analysis of melanoma biopsy specimens have shown a differential ganglioside expression among different sites of tumor, pigmentation, and histopathologic types. Results of cultured melanoma cell lines differed from those of biopsy specimens, but ganglioside expression also differed among the site of tumor, tumor size, histopathologic types, and chemosensitivity. GM3 positively correlated with a good prognosis in both biopsy and cultured melanomas.