Antitumor effects of the GM3(Neu5Gc) ganglioside-specific humanized antibody 14F7hT against Cmah-transfected cancer cells.

The GM3(Neu5Gc) ganglioside represents a tumor-specific antigen that is considered a promising target for cancer immunotherapy. We previously demonstrated that the humanized antibody 14F7hT, specific for this ganglioside, exhibited significant antitumor effects in preclinical hematological tumor models. As this antibody recognizes human tumor tissues from several origins, we addressed its potential effect on different tumor types. The use of cell lines for testing GM3(Neu5Gc)-targeting strategies, in particular for human malignancies, is complicated by the absence in humans of functional cytidine monophospho-N-acetyl-neuraminic acid hydroxylase (CMAH), the enzyme required for Neu5Gc sialic acid biosynthesis. Quantitative flow cytometry revealed the absence of surface GM3(Neu5Gc) in several human but also mouse cell lines, in the last case due to low expression of the enzyme. Hypoxia-induced expression of this ganglioside on human SKOV3 cells was observed upon culture in Neu5Gc-containing medium without evidence for CMAH-independent biosynthesis. However, only transfection of the mouse Cmah gene into human SKOV3 and mouse 3LL cells induced a stable expression of GM3(Neu5Gc) on the cancer cell surface, resulting in effective models to evaluate the antitumor responses by 14F7hT in vitro and in vivo. This antibody exerted antibody-dependent cell-mediated cytotoxicity (ADCC) and in vivo antitumor effects on these Cmah-transfected non-hematological tumors from both mouse and human origin. These results contribute to validate GM3(Neu5Gc) as a relevant target for cancer immunotherapy and reinforces the value of 14F7hT as a novel anti-cancer drug

Marine seagrass extract of Thalassia testudinum suppresses colorectal tumor growth, motility and angiogenesis by autophagic stress and immunogenic cell death pathways

Marine plants have become an inexhaustible reservoir of new phytopharmaceuticals for cancer treatment. We demonstrate in vitro/in vivo antitumor efficacy of a standardized polyphenol extract from the marine angiosperm Thalassia testudinum (TTE) in colon tumor cell lines (RKO, SW480, and CT26) and a syngeneic allograft murine colorectal cancer model. MTT assays revealed a dose-dependent decrease of cell viability of RKO, CT26, and SW480 cells upon TTE treatment with IC50 values of, respectively, 175, 115, and 60 mu g/mL. Furthermore, TTE significantly prevented basal and bFGF-induced angiogenesis in the chicken chorioallantoic membrane angiogenesis assay. In addition, TTE suppressed bFGF-induced migration of endothelial cells in a wound closure assay. Finally, TTE treatment abrogated CT26 colorectal cancer growth and increased overall organism survival in a syngeneic murine allograft model. Corresponding transcriptome profiling and pathway analysis allowed for the identification of the mechanism of action for the antitumor effects of TTE. In line with our in vitro/in vivo results, TTE treatment triggers ATF4-P53-NF kappa B specific gene expression and autophagy stress pathways. This results in suppression of colon cancer cell growth, cell motility, and angiogenesis pathways in vitro and in addition promotes antitumor immunogenic cell death in vivo

Wiskott-Aldrich syndrome protein-mediated actin dynamics control type-I interferon production in plasmacytoid dendritic cells

Mutations in Wiskott-Aldrich syndrome (WAS) protein (WASp), a regulator of actin dynamics in hematopoietic cells, cause WAS, an X-linked primary immunodeficiency characterized by recurrent infections and a marked predisposition to develop autoimmune disorders. The mechanisms that link actin alterations to the autoimmune phenotype are still poorly understood. We show that chronic activation of plasmacytoid dendritic cells (pDCs) and elevated type-I interferon (IFN) levels play a role in WAS autoimmunity. WAS patients display increased expression of type-I IFN genes and their inducible targets, alteration in pD

Direct validation of NGcGM3 ganglioside as a new target for cancer immunotherapy

OBJECTIVE: The target concept means not only an aberrant expression of a particular molecule in tumour tissues but also evidence of a clear therapeutic advantage, as a consequence of immune-intervention, in an antigen-positive relevant tumour model. Since we reported the presence of NGcGM3 ganglioside in human breast tumours years ago and though Phase I clinical trials of a ganglioside containing vaccine have been conducted, a definitive direct validation of this peculiar molecule as target for cancer immunotherapy has remained unperformed. METHODS: Two animal models were used: leghorn chickens and C57BL/6 mice. The murine 3LL-D122 cell line, the derived subcutaneous tumours and metastatic lung lesions were processed for gangliosides identification. Active immunotherapy experiments in the 3LL-D122 spontaneous lung metastasis model were performed with NGcGM3/VSSP vaccine prepared by conjugation of NGcGM3 with the outer membrane proteins of Neisseria meningitides. RESULTS: The 3LL-D122 Lewis lung carcinoma results were consistent with an increased expression of NGcGM3 from primary tumours to metastatic lesions, as observed in human breast cancer samples. Both vaccines, prepared with synthetic or natural-source-derived ganglioside, showed similar anti-tumour and immunogenicity profiles. Finally, a clear involvement of NK1.1(+) cells and CD8(+) T cells in the anti-metastatic effect elicited by the vaccine was manifested. CONCLUSIONS: While 'proof of concept' Phase II and III clinical trials with the NGcGM3/VSSP vaccine in cancer patients are currently ongoing these results reasonably sustain the validation of this peculiar ganglioside as a novel target for cancer immunotherapy.Fil: Labrada, Mayrel. Center of Molecular Immunology; CubaFil: Clavell, Marilyn. Center of Molecular Immunology; CubaFil: Bebelagua, Yanín. Center of Molecular Immunology; CubaFil: De León, Joel. Center of Molecular Immunology; CubaFil: 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. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Veloso, Roberto C. Center of Molecular Immunology; CubaFil: Vérez, Vicente. Center of Molecular Immunology; CubaFil: Fernández, Luis E.. Center of Molecular Immunology; Cub