ABSTRACT
Genetically modified tumor cells harboring immunomodulators may be used as therapeutic vaccines to stimulate antitumor immunity. The therapeutic benefit of these tumor vaccines is extensively investigated and mechanisms by which they boost antitumor response may be further explored. Tumor cells are large secretors of extracellular vesicles (EVs). These EVs are able to vehiculate RNA and proteins to target cells, and engineered EVs also vehiculate recombinant proteins. In this study, we explore immunomodulatory properties of EVs derived from antitumor vaccines expressing the TNFSF ligands 4-1BBL and OX40L, modulating immune response mediated by immune cells and eliminating tumors. Our results suggest that the EVs secreted by genetically modified tumor cells harboring TNFSF ligands can induce T cell proliferation, inhibit the transcription factor FoxP3, associated with the maintenance of Treg phenotype, and enhance antitumor activity mediated by immune cells. The immunomodulatory extracellular vesicles have potential to be further engineered for developing new approaches for cancer therapy.
Subject(s)
4-1BB Ligand/immunology , Cancer Vaccines/therapeutic use , Melanoma, Experimental/immunology , Melanoma, Experimental/therapy , OX40 Ligand/immunology , 4-1BB Ligand/genetics , Animals , Antigen-Presenting Cells/immunology , CD4-Positive T-Lymphocytes/immunology , Cancer Vaccines/genetics , Cancer Vaccines/immunology , Cell Line, Tumor , Extracellular Vesicles/genetics , Extracellular Vesicles/immunology , Extracellular Vesicles/ultrastructure , Forkhead Transcription Factors/antagonists & inhibitors , Immunologic Factors/genetics , Immunologic Factors/immunology , Immunologic Factors/therapeutic use , In Vitro Techniques , Lymphocyte Activation , Melanoma, Experimental/genetics , Mice , Mice, Inbred C57BL , Microscopy, Electron, Transmission , OX40 Ligand/geneticsABSTRACT
PURPOSE: Regulatory T cells (Tregs) impair the clinical benefit of cancer immunotherapy. To optimize the antitumor efficacy of therapeutic dendritic cell (DC) vaccines, we aimed to inhibit Foxp3, a transcription factor required for Treg function. METHODS: Mice bearing established syngeneic LM3 and 4T1 breast tumors were treated with antitumor DC vaccines and a synthetic peptide (P60) that has been shown to inhibit Foxp3. RESULTS: Treatment with P60 improved the therapeutic efficacy of DC vaccines in these experimental models. In addition, monotherapy with P60 inhibited tumor growth in immunocompetent as well as in immuno-compromised animals bearing established tumors. We found expression of Foxp3 in human and murine breast tumor cells. P60 inhibited IL-10 secretion in breast cancer cells that expressed Foxp3. CONCLUSIONS: Our results suggest that Foxp3 blockade improves the therapeutic efficacy of DC vaccines by inhibition of Tregs and through a direct antitumor effect. This strategy could prove useful to neutralize the immunosuppressive microenvironment and to boost antitumor immunity in breast cancer.
Subject(s)
Breast Neoplasms/therapy , Cell-Penetrating Peptides/administration & dosage , Dendritic Cells/transplantation , Forkhead Transcription Factors/antagonists & inhibitors , T-Lymphocytes, Regulatory/drug effects , Animals , Breast Neoplasms/immunology , Breast Neoplasms/metabolism , Cancer Vaccines/administration & dosage , Cancer Vaccines/pharmacology , Cell Line, Tumor , Cell-Penetrating Peptides/pharmacology , Dendritic Cells/immunology , Female , Humans , Immunotherapy , Mice , T-Lymphocytes, Regulatory/immunology , Treatment Outcome , Tumor Microenvironment/drug effects , Xenograft Model Antitumor AssaysABSTRACT
The discovery of novel targets that can be pharmacologically exploited to lead to a better disease outcome has long been an aim of biomedical research. At present, the technology and robotisation available have pushed the search for novel molecules to a high-throughput screening (HTS) context, making it possible to screen several hundreds of compounds or genes in a single day. High-content screenings (HCS) have added a refined complexity to the screening processes, as the information drawn from an image- based assay is more complete than the monoparametric readouts obtained in classical HTS assays. Here, we review the development of HCS platforms to identify molecules influencing FOXO nuclear relocation and activation as pharmacological targets, their applicability and the future directions of the screening field.