RESUMEN
A20 is an ubiquitin-editing enzyme that ensures the transient nature of inflammatory signaling pathways induced by cytokines like TNF-α and IL-1 or pathogens via Toll-like receptor (TLR) pathways. It has been identified as a negative regulator of dendritic cell (DC) maturation and attenuator of their immunostimulatory properties. Ex vivo A20-depleted dendritic cells showed enhanced expression of pro-inflammatory cytokines and costimulatory molecules, which resulted in hyperactivation of tumor-infiltrating T lymphocytes and inhibition of regulatory T cells. In the present study, we demonstrate that a synthetic molecule consisting of a CpG oligonucleotide TLR9 agonist linked to A20-specific siRNAs silences its expression in TLR9+ mouse dendritic cells in vitro and in vivo. In the B16 mouse melanoma tumor model, silencing of A20 enhances the CpG-triggered induction of NFκB activity followed by elevated expression of IL-6, TNF-α and IL-12. This leads to potentiated antitumor immune responses manifested by increased numbers of tumor-specific cytotoxic T cells, high levels of tumor cell apoptosis and delayed tumor growth. Our findings confirm the central role of A20 in controlling the immunostimulatory potency of DCs and provide a strategy for simultaneous A20 silencing and TLR activation in vivo.
Asunto(s)
Cisteína Endopeptidasas/efectos de los fármacos , Silenciador del Gen , Péptidos y Proteínas de Señalización Intracelular/efectos de los fármacos , Melanoma Experimental/tratamiento farmacológico , ARN Interferente Pequeño/farmacología , Receptor Toll-Like 9/efectos de los fármacos , Animales , Western Blotting , Línea Celular Tumoral , Citocinas/metabolismo , Células Dendríticas/efectos de los fármacos , Células Dendríticas/inmunología , Femenino , Inmunidad Humoral/efectos de los fármacos , Inmunidad Humoral/fisiología , Melanoma Experimental/inmunología , Ratones , Ratones Endogámicos C57BL , Microscopía Confocal , Terapia Molecular Dirigida , FN-kappa B/metabolismo , Proteína 3 Inducida por el Factor de Necrosis Tumoral alfaRESUMEN
Stem cells with certain characteristics have become promising tools for molecular medicine. They have the potential to self-regenerate and to differentiate into specific tissues. Besides their great potential, embryonic stem cells (ESC) run the risk of enhanced tumorigenesis. The use of human embryonic stem cells (hESC) is ethically problematic because their isolation involves the destruction of human embryos. Recently developed methods generate are able to pluripotent stem cells from fibroblasts. Alternatives for ESC are adult stem cells (ASC) derived from bone marrow, cord blood, amniotic fluid and other tissues. The following article is on the basis of testimony of Lukas Kenner for the German Bundestag about the use of ESC for research, therapy and drug development. Ethical aspects are taken into consideration.