Terminally sialylated and fucosylated complex N-glycans are involved in the malignant behavior of high-grade glioma

Gliomas are the most common intracranial primary tumors, for which very few therapeutic options are available. The most malignant subtype is the glioblastoma, a disease associated with a 5-year survival rate lower than 5%. Given that research in glycobiology continues highlighting the role of glycans in tumor cell biology, it offers an interesting niche for the search of new therapeutic targets. In this study, we characterized aberrant glycosylation and its impact on cell biology over a broad panel of high- and low-grade glioma cell lines. Results show high expression of terminal Lewis glycans, mainly SLex, and overexpression of sialyl- and fucosyltransferases involved in their biosynthesis in high-grade glioma cell lines. Moreover, we report an association of complex multi-antennary N-glycans presenting β1,6-GlcNAc branches with the high-grade glioma cells, which also overexpressed the gene responsible for these assemblies, MGAT5. In addition, downmodulation of N-glycosylation by treatment with the inhibitors Tunicamycin/Swainsonine or MGAT5 silencing decreased SLex expression, adhesion and migration in high-grade glioma cells. In contrast, no significant changes in these cell capacities were observed in low-grade glioma after treatment with the N-glycosylation inhibitors. Furthermore, inhibition of histone deacetylases by Trichostatin A provoked an increase in the expression of SLex and its biosynthetic related glycosyltransferases in low-grade glioma cells. Our results describe that aggressive glioma cells show high expression of Lewis glycans anchored to complex multi-antennary N-glycans. This glycophenotype plays a key role in malignant cell behavior and is regulated by histone acetylation dependent mechanisms.Fil: Cuello, Héctor Adrián. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ferreira, Gretel Magalí. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; ArgentinaFil: Gulino, Cynthia Antonella. Universidad Nacional de Quilmes; ArgentinaFil: Gomez Toledo, Alejandro. Lund University; SueciaFil: Segatori, Valeria Inés. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gabri, Mariano Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentin

Frequent co-expression of EGFR and NeuGcGM3 ganglioside in cancer: it’s potential therapeutic implications

Interaction between epidermal growth factor receptor (EGFR) signaling with GM3 ganglioside expression has been previously described. However, little is known about EGFR and NeuGcGM3 co-expression in cancer patients and their therapeutic implications. In this paper, we evaluate the co-expression of EGFR and NeuGcGM3 ganglioside in tumors from 92 patients and in two spontaneous lung metastasis models of mice (Lewis lung carcinoma (3LL-D122) in C57BL/6 and mammary carcinoma (4T1) in BALB/c). As results, co-expression of EGFR and NeuGcGM3 ganglioside was frequently observed in 63 of 92 patients (68 %), independently of histological subtype. Moreover, EGFR is co-expressed with NeuGcGM3 ganglioside in the metastasis of 3LL-D122 and 4T1 murine models. Such dual expression appears to be therapeutically relevant, since combined therapy with mAbs against these two molecules synergistically increase the survival of mice treated. Overall, our results suggest that NeuGcGM3 and EGFR may coordinately contribute to the tumor cell biology and that therapeutic combinations against these two targets might be a valid strategy to explore.Fil: Palomo, Addys González. Centro de Inmunología Molecular; CubaFil: Santana, Rancés Blanco. Centro de Inmunología Molecular; CubaFil: Pérez, Xiomara Escobar. Instituto Nacional de Oncología y Radiobiología; CubaFil: Santana, Damián Blanco. Instituto Nacional de Oncología y Radiobiología; CubaFil: Gabri, Mariano Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Monzon, Kalet León. Centro de Inmunología Molecular; CubaFil: Pérez, Adriana Carr. Centro de Inmunología Molecular; Cub

Racotumomab: an anti=idiotype vaccine related to N=glycolyl=containing=gangliosides: Preclinical and clinical data

Neu-glycolyl (NeuGc)-containing gangliosides are attractive targets for immunotherapy with anti-idiotype mAbs, because these glycolipids are not normal components of the cytoplasmic membrane in humans, but their expression has been demonstrated in several human malignant tumors. Racotumomab is an anti-idiotype mAb specific to P3 mAb, an antibody which reacts to NeuGc-containing gangliosides, sulfatides, and other antigens expressed in tumors. Preparations containing racotumomab were able to induce a strong anti-metastatic effect in tumor-bearing mice. Different Phase I clinical trials have been conducted in patients with advanced melanoma, breast cancer, and lung cancer. The results of these clinical trials demonstrated the low toxicity and the high immunogenicity of this vaccine. The induced antibodies recognized and directly killed tumor cells expressing NeuGcGM3. A Phase II/III multicenter, controlled, randomized, double blind clinical trial was conducted to evaluate the effect of aluminum hydroxide-precipitated racotumomab vaccine in overall survival in patients with advanced non-small cell lung cancer. The clinical results of this study showed a significant clinical benefit in the patients who were treated with the anti-idiotype vaccine.Fil: Vazquez, Ana M.. Center of Molecular Immunology; CubaFil: Hernandez, Ana M.. Center of Molecular Immunology; CubaFil: Macias, Amparo. Center of Molecular Immunology; CubaFil: Montero, Enrique. Center of Molecular Immunology; CubaFil: Gomez, Daniel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Alonso, Daniel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Gabri, Mariano Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Gomez, Roberto E.. Elea Laboratories; Argentin

Optimization of molecular detection of GD2 synthase mRNA in retinoblastoma

Extraocular dissemination is the main cause of death in patients with retinoblastoma in developing countries and there are few molecular markers that could be used for evaluation of minimal disseminated disease. The expression of the ganglioside GD2 is present in retinoblastoma cells metastatic to the bone marrow and the enzyme GD2 synthase activity is detected in neuroblastoma, which shares many phenotypic features with retinoblastoma. Our purpose was to optimize the detection of GD2 synthase expression by reverse transcription-polymerase chain reaction (RT-PCR) followed by nested-PCR in human retinoblastoma cell lines and patient samples. The optimization strategy was carried out by using the retinoblastoma cell lines Y79 and WERI-Rb1 and specific primers designed for the human sequence of the GD2 synthase mRNA. We detected GD2 synthase expression with at least 200 pg and 40 pg of total RNA extracted from cultured retinoblastoma cells, using a first round of RT-PCR amplification and a second round of nested-PCR, respectively. We have also confirmed the detection of GD2 synthase by RT-PCR and immunohistochemical expression of the ganglioside in human retinoblastoma tumors xenotransplanted in nude mice. In a study from tumor bank specimens from 8 retinoblastoma patients, we were able to demonstrate the presence of GD2 synthase mRNA in blood and cerebrospinal fluid samples in cases of extraocular dissemination of the tumor. The sequence was not detected in samples from children with low-risk disease or healthy adult volunteers. The detection of GD2 synthase mRNA through an optimized nested RT-PCR assay may be a promising tool for the assessment of minimal disseminated disease in enucleated patients.Fil: Laurent, Viviana Eunice. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan". Servicio de Hemato-Oncología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Otero, Laura L.. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Vazquez, Valeria. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Camarero, Sandra. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Gabri, Mariano Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Labrada, Maria. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Garcia de Davila, Maria Teresa. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Chantada, Guillermo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan". Servicio de Hemato-Oncología; ArgentinaFil: Alonso, Daniel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentin

Ensayos pre-clínicos de dos vacunas inmunoterapéuticas con actividad antitumoral desarrolladas a partir de gangliósidos

Para el año 1934 la toxina de Coley era el único tratamiento sistémico para el tratamiento de cáncer. Este preparado fue desarrollado unos años antes por el prestigioso cirujano del Memorial Hospital de New York, William B. Coley, utilizando toxinas bacterianas de los géneros Serratia y Streptococcus. Este producto se convirtió así en la primera vacuna oncológica y en uno de los primeros tratamientos sistémicos del cáncer. A pesar de los experimentos iniciales del siglo pasado, luego de los ensayos de Coley la inmunoterapia oncológica fue dejada de lado por el advenimiento de las drogas quimioterapéuticas y las mejoras en la radioterapia. En las últimas décadas se ha vuelto a observar a la inmunoterapia como una estrategia complementaria válida para el tratamiento de cáncer. Este nuevo interés sobre este tipo de tratamientos, tiene sus bases en el gran avance alcanzado en el entendimiento de los mecanismos inmunológicos y de los procesos que dominan la biología tumoral. En esta tesis se presentan resultados relativos a dos vacunas desarrolladas a partir de gangliósidos, moléculas de membrana anfipáticas que pertenecen a la familia de los glicoesfingolípidos con por lo menos, un residuo de ácido siálico lo cual es una característica distintiva de estos compuestos. Los resultados se centran en la evaluación de los efectos tóxicos, la respuesta antitumoral y la modulación inmunológica desencadenados por la aplicación de vacunas inmunoterapéuticas a base de gangliósidos, consistentes en un anticuerpo anti-idiotipo dirigido a gangliósidos glicolilados (anticuerpo 1E1O) y de una vacuna molecular del gangliósido NacGM3 conjugado a proteínas externas de membrana de N. Meningitidis proteoliposomas de muy pequeño tamaño (NacGM3/VSSP). Con este fin se evaluará también el perfil de los modelos murinos experimentales de cáncer mamario y melanoma a emplearse para cada vacuna, respectivamente. Los resultados demuestran que los modelos animales elegidos presentan características adecuadas para ser utilizados como herramientas de evaluación de los efectos y mecanismos desencadenados por la inmunización con las vacunas. La línea celular de cancer mamario murino F3II crece en el espacio subcutáneo desarrollando un fenotipo tumoral altamente maligno. Su portación produce un cuadro inmunoestimulatorio posiblemente ligado a la secreción de GM-CSF, citoquina ante la cual se modifica su respuesta proliferativa. Además estas células son reactivas al anticuerpo P3, precursor del 1E10, lo que la convierte en un modelo apropiado para la evaluación de la respuesta antitumoral de 1E10. La inmunización de ratones con el preparado 1E10-KLH no produce efectos tóxicos de magnitud en los animales, desarrollando una respuesta tumoral que es capaz de reconocer a las células F3II. Utilizando este proceso de inmunización se puede observar un retardo en el crecimiento tumoral y una disminución significativa en el recuento de metástasis espontáneas en los ratones tratados. Además se evaluó a la línea B16 crecida en animales singénicos como modelo de estudio de los efectos producidos por la vacunación con NacGM3/VSSP. Las células B16 presentan en su membrana al gangliósido NacGM3, reaccionando positivamente ante la presencia del mismo en el medio de cultivo. La vacunación de ratones C57 con NacGM3/VSSP desarrolla una respuesta inmunológica humoral que es capaz de reconocer a los componentes de la vacuna y a las células de melanoma B16. La aplicación de la vacuna no produce efectos tóxicos de importancia. La vacunación con NacGM3/VSSP genera una respuesta antitumoral que se manifiesta en el rechazo del desafío tumoral en el 100% de los animales vacunados. Esta respuesta se mantiene en el tiempo hasta tres meses luego de finalizada la misma. La respuesta antitumoral obtenida es dosis dependiente ya que se pudo observar una actividad antitumoral creciente en lotes de ratones inmunizados con una concentración vacunal de hasta 360 μg/dosis y específica hacia células que expresan el gangliósido NacGM3). La vacunación con NacGM3/VSSP desarrolla una respuesta de anticuerpos con preponderancia del isotipo IgG2b. Estos anticuerpos reconocen cortes de tumor B16 siendo su epítope reactivo el residuo de ácido sialico presente en las células. La investigación básica en vacunas provee un mejor entendimiento de los mecanismos inmunológicos involucrados en el rechazo tumoral inducidos por la vacunación. Los ensayos preclínicos con modelos animales de cáncer son de importancia capital en el estudio de los efectos inmuno modulatorios de estas vacunas y en la evaluación de sus capacidades terapéuticas a nivel clínico.By 1934 Coley's toxin was the only systemic treatment for cancer. This compound was developed few years before for the famous surgeon from The Memorial Hospital of New York, William B. Coley, using bacterial toxins from Serratia and Streptococcus. This product become the first cancer vaccine and one of the first systemic treatments for cancer. Despite the initial experiments carried out in the last century, after Coley attempts cancer immunotherapy was abandoned due to the appearance of quimiotherapeutic drugs and improvements in radiotherapy. In the last decades, immunotherapy is seeing again as a valid adiuvant therapy for cancer treatment. This new interest in this kind of treatments, is based in the important advance reached in the understanding of immunology and the processes that govern tumor biology. In this thesis, results related with two vaccines based in gangliosides are presented. Gangliosides are amphipatic membrane molecules that belong to the glicoesfingolipid family, having at least one residue of sialic acid, which is a distinctive characteristic of this kind of compounds. The results focus in the evaluation of toxicity, antitumoral response and the immunological modulation due to the application of this two vaccines, one an antiidiotypic antibody against glycolilated gangliosides (1E1o antibody) and other a molecular vaccine composed by the ganglioside NacGM3 conjugated to proteins from the outer membrane of N. Meningitidis in proteoliposomes of very small size (NacGM3/VSSP). With this reasoning in mind, the profile of the experimental murine models of breast cancer and melanoma to be employed with each vaccine, was also evaluated. Results demonstrated that the animal models chosen have the characteristics needed to be used as evaluation tools of the effects and mechanisms developed by the immunization with the vaccines. F3II murine breast cancer cell line grows in the subcutis developing a highly malignant tumor phenotype. Its bearing produce an immunoestimulatory effect probably related to the secretion of GM-CSF, a cytoquine able to modify its proliferative response. Furthermore, this cells are reactive to P3 antibody, a precursor of 1E10, becoming a very adequate model for the evaluation of 1E10 antitumor response. Immunization of mice with the preparation 1E10-KLH did not produce relevant toxic effects in the animals, developing a humoral response able to recognize F3II cells. Using this immunization process it can be observed a delay in tumor growth an a significant decrease in the number of spontaneous metastasis in treated animals. Also, the B16 line, growing in singenic animals, as a study model of the effect produced by vaccination with NacGM3/VSSP, was evaluated. B16 cells have in its membrane NacGM3 ganglioside. Vaccination of C57 mice with NacGM3/VSSP developed a humoral immunologic response able to recognize both, components of the vaccine and B16 melanoma cells. Administration of the vaccine did not produce relevant toxic effects. Vaccination with NacGM3/VSSP generated an antitumoral response that translated in the rejection of the tumor challenge in 100% of the vaccinated animals. This response is sustained in the time up to three months after final inoculation. The antitumoral response obtained is dose-dependent since was observed an increasing antitumoral activity in mice immunized with a vaccine concentration of up to 360 μg/dose, being specific towards cells expressing NacGM3 ganglioside. Vaccination with NacGM3/VSSP developed an antibody response mostly based in the isotype IgG2b. This antibodies recognize B16 tumor slides being its reactive epitope the sialic acid residue which is present in the cells. Basic research in vaccines provide a better understanting of the immunologic mechanisms involved in tumor rejection induced by vaccination. Preclinical experiments with animal models of cancer are of utmost importance in the study of the immunomodulatory effects of this vaccines and the evaluation of its therapeutic capabilities at the clinical level.Fil:Gabri, Mariano Rolando. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Racotumomab for treating lung cancer and pediatric refractory malignancies

Introduction: Racotumomab (originally known as 1E10 mAb) is an anti-idiotype murine IgG1 directed to membrane glycoconjugates expressed in aggressive solid tumors. It was developed as a mirror image of the idiotype of another antibody against N-glycolyl-containing molecules, such as the NeuGcGM3 ganglioside. After a successful phase II/III study, racotumomab formulated in alum was conditionally approved in Latin American countries as maintenance therapy for advanced non-small cell lung cancer. Areas covered: This review analyzes the biology of the target antigen, summarizes preclinical studies and discusses clinical trials in adults and the pediatric experience with racotumomab. Expert opinion: Proper patient selection and combination with chemotherapy, radiotherapy or checkpoint inhibitors appear to be critical issues to maximize the effects of racotumomab vaccination in lung cancer. In a recent phase I clinical trial in children with relapsed or resistant neuroectodermal malignancies, racotumomab was well tolerated and immunogenic, and its evaluation as immunotherapy for high-risk neuroblastoma is warranted.Fil: Gabri, Mariano Rolando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cacciavillano, Walter. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría ; ArgentinaFil: Chantada, Guillermo Luis. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Role of cell surface GM3 ganglioside and sialic acid in the antitumor activity of a GM3-based vaccine in the murine B16 melanoma model

Purpose: To examine the role of GM3 monosialoganglioside and sialic acid in the antitumor activity of a vaccine based on GM3, hydrophobically conjugated with the outer-membrane-protein complex from Neisseria meningitidis (GM3/VSSP). Methods: In order to evaluate the relationship between antitumor activity and the presence of GM3 on the surface of tumor cells, we used two murine tumor cell lines with different ganglioside expression. Syngeneic mice were immunized with four i.m. doses of GM3/VSSP (120 μg) at 14-day intervals and challenged subcutaneously with tumor cells. Results: B16 melanoma cells showed GM3 on cell surface and GM3-dependent in vitro growth. As expected, preimmunization with the vaccine significantly inhibited tumor formation and prolonged survival in mice challenged with B16 cells. In contrast, no antitumor effect was observed in mice challenged with GM3-negative F3II mammary carcinoma cells. The reactivity of sera from immunized mice against B16 cells was confirmed by flow cytometry and immunoperoxidase staining. Depletion of sialic acid residues from the cell surface completely abolished antibody response against melanoma cells. Conclusions: These results indicate that the antitumor activity of GM3/VSSP is associated with GM3 expression on tumor cell surface and demonstrate a major role of sialic acid in the humoral response of vaccinated mice.Fil: Gabri, Mariano Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Ripoll, Giselle Vanina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Alonso, Daniel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Gomez, Daniel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentin

Antitumor properties of an anti-idiotypic monoclonal antibody in relation to N-glycolyl-containing gangliosides

We examined the antitumor effects of 1E10 monoclonal antibody, an anti-idiotypic IgG to an IgM monoclonal antibody, named P3, that reacts specifically with N-glycolyl-containing gangliosides and also recognizes antigens in human breast and melanoma tumors. Two murine tumor cell lines positive for the P3 antibody, F3II mammary carcinoma (BALB/c) and B16 melanoma (C57BL/6), were employed. In BALB/c mice, vaccination with several i.p. doses at 14-day intervals of 50 microgram of 1E10 coupled to keyhole limpet hemocyanin in Freund's adjuvant, significantly reduced s.c. tumor growth of F3II carcinoma cells and the number of spontaneous lung metastases. Also, the effect of 1E10 as a biological response modifier on tumor lung colonization was evaluated in C57BL/6 mice injected i.v. with B16 melanoma cells. Interestingly, i.v. administration of 10 microgram of uncoupled 1E10 antibody, 10-14 days after inoculation of B16 cells, dramatically reduced the number of experimental metastases in comparison with lungs from mice treated with an irrelevant IgG. The present data suggest that this 'non-internal image' anti-idiotypic monoclonal antibody may activate more than one mechanism of antitumor response against melanoma and mammary tumor cells.Fil: Vázquez, Ana María. Centro de Inmunología Molecular; CubaFil: Gabri, Mariano Rolando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Hernández, Ana María. Centro de Inmunología Molecular; CubaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Beausoleil, Irene. Centro de Inmunología Molecular; CubaFil: Gomez, Daniel Eduardo. Centro de Inmunología Molecular; CubaFil: Pérez, Rolando. Centro de Inmunología Molecular; Cub

Antitumor Protection by NGcGM3/VSSP Vaccine Against Transfected B16 Mouse Melanona Cells Overexpressing N-Glycolylated gangliosides

Background: Cancer vaccines are designed to modulate immunological responses against tumor cells through the presentation of tumor antigens. Materials and Methods: The mouse mRNA of the cytidine monophospho-N-acetylneuraminic acid hydroxylase (Cmah) gene, the enzyme that catalyzes the synthesis of N-glycolylneuraminic acid (NGc), was cloned and transfected into the B16 melanoma cell line. Transfected cells (B16-H) were characterized and used as an NGcGM3-positive primary tumor model for the evaluation of the therapeutic activity of the NGcGM3/VSSP vaccine. Results: The presence of NGcGM3 in B16-H cells promoted proliferation and adhesion in vitro, but resulted in reduced tumorigenicity in vivo. However, B16-H cells developed growing tumors in mice where NGcGM3/VSSP vaccination induced a therapeutic antitumor activity. NGcGM3/VSSP was ineffective in mice inoculated with parental B16 or B16-H cells that had lost NGcGM3 expression. Conclusion: The presence of NGcGM3 in tumor cells is critical for the antitumor activity of NGcGM3/VSSP vaccine.Fil: Segatori, Valeria Inés. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Otero, Laura. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernandez, Luis Enrique. Instituto de Inmunología Molecular; CubaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gabri, Mariano Rolando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin