The mechanisms of cancer involve changes in multiple biological pathways. Multitarget molecules, which are components of animal venoms, are therefore a potential strategy for treating tumors. The objective of this study was to screen the effects of Phoneutria nigriventer spider venom (PnV) on tumor cell lines. Cultured human glioma (NG97), glioblastoma (U-251) and cervix adenocarcinoma (HeLa) cells, and nontumor mouse fibroblasts (L929) were treated with low (14 µg/ml) and high (280 µg/ml) concentrations of PnV, and analyzed through assays for cell viability (thiazolyl blue tetrazolium blue), proliferation (carboxyfluorescein succinimidyl ester), death (annexin V/propidium iodide [Pi]), the cell cycle (Pi), and migration (wound healing and transwell assay). The venom decreased the viability of U-251 cells, primarily by inducing cell death, and reduced the viability of NG97 cells, primarily by inhibiting the cell cycle. The migration of all the tumor cell lines was delayed when treated with venom. The venom significantly affected all the tumor cell lines studied, with no cytotoxic effect on normal cells (L929), although the nonglial tumor cell (HeLa) was less sensitive to PnV. The results of the current study suggest that PnV may be composed of peptides that are highly specific for the multiple targets involved in the hallmarks of cancer. Experiments are underway to identify these molecules.
Dendritic cells (DCs) vaccine is a potential tool for oncoimmunotherapy. However, it is known that this therapeutic strategy has failed in solid tumors, making the development of immunoadjuvants highly relevant. Recently, we demonstrated that Phoneutria nigriventer spider venom (PnV) components are cytotoxic to glioblastoma (GB) and activate macrophages for an antitumor profile. However, the effects of these molecules on the adaptive immune response have not yet been evaluated. This work aimed to test PnV and its purified fractions in DCs in vitro. For this purpose, bone marrow precursors were collected from male C57BL6 mice, differentiated into DCs and treated with venom or PnV-isolated fractions (F1—molecules < 3 kDa, F2—3 to 10 kDa and F3—>10 kDa), with or without costimulation with human GB lysate. The results showed that mainly F1 was able to activate DCs, increasing the activation-dependent surface marker (CD86) and cytokine release (IL-1β, TNF-α), in addition to inducing a typical morphology of mature DCs. From the F1 purification, a molecule named LW9 was the most effective, and mass spectrometry showed it to be a peptide. The present findings suggest that this molecule could be an immunoadjuvant with possible application in DC vaccines for the treatment of GB.
Malignant primary brain tumors remain among the most difficult cancers to treat. In malignant tissues, macrophages are accumulated in a high infiltration being known as tumor-associated macrophages (TAMs). These cells are associated with poor prognostics in many types of cancer. Studies in our group demonstrated that the venom of Phoneutria nigriventer (PnV), a wandering spider from South America, has reduced the development of glioblastoma (GBM) in a murine model, inducing a large infiltrate of TAMs. Subsequently, in vitro results demonstrated that PnV activates macrophages, increasing the ability to kill tumor cells. The aim of this study was to analyze the effects of the peptide SNX-482 presented in the venom of Hysterocrates gigas in macrophages for further correlation with the PnV. Macrophages were differentiated from bone marrow precursors collected from male C57BL6 mice and differentiated for 7 days with M-CSF. These cells were used for polarization and coculture with T cells and analyzed by flow cytometry. PCR Array was also performed (QIAGEN) for the analysis of gene expression. The results showed that SNX-482 could activate macrophages in a not dose-dependent response. There was an increase in the main activation markers (CD40, CD80, CD86, CD68, CD83, and MHCII). The polarization indicated that the peptide potentiated the proinflammatory effect of M1 macrophages (increased MHCII and iNOS). The screening of 86 cancer-related genes showed that the Ccr4, Pdcd1, Gzmb, and IFN-γ genes had an increase in their expression. Furthermore, we developed in C57BL/6 mouse a pre-clinical model of intracranial glioblastoma using the Gl261 cell line. The results showed an applied-easy-safe model that could alter the gene expression of cancer markers. Taken together, all the results contributed to increasing the knowledge about the peptide SNX-482 and the model for further pre-clinical assays of glioblastoma, making a great advance in the development of new treatments.
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