RESUMEN
Granzymes are generally recognized for their capacity to induce various pathways of perforin-dependent target cell death. Within this serine protease family, Granzyme M (GrzM) is unique owing to its preferential expression in innate effectors such as natural killer (NK) cells. During Listeria monocytogenes infection, we observed markedly reduced secretion of macrophage inflammatory protein-1 alpha (MIP-1α) in livers of GrzM-deficient mice, which resulted in significantly impaired NK cell recruitment. Direct stimulation with IL-12 and IL-15 demonstrated that GrzM was required for maximal secretion of active MIP-1α. This effect was not due to reduced protein induction but resulted from heightened intracellular accumulation of MIP-1α, with reduced release. These results demonstrate that GrzM is a critical mediator of innate immunity that can regulate chemotactic networks and has an important role in the initiation of immune responses and pathogen control.
Asunto(s)
Quimiocina CCL3/metabolismo , Granzimas/metabolismo , Inmunidad Innata , Células Asesinas Naturales/enzimología , Listeriosis/enzimología , Animales , Células Cultivadas , Quimiotaxis de Leucocito , Técnicas de Cocultivo , Modelos Animales de Enfermedad , Granzimas/deficiencia , Granzimas/genética , Humanos , Interleucinas/metabolismo , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/microbiología , Listeria monocytogenes/inmunología , Listeria monocytogenes/patogenicidad , Listeriosis/genética , Listeriosis/inmunología , Listeriosis/microbiología , Ratones , Ratones Noqueados , Factores de TiempoRESUMEN
BACKGROUND: Locomotion of cancer cells can be induced by TNF and other motogenic factors secreted by cells of the tumour microenvironment such as macrophages. Based on our recent findings that the TNF receptor adaptor protein FAN mediates TNF-induced actin reorganisation and regulates the directed migration of immune cells responding to chemotactic cues, we addressed the role of FAN in cancer cell motility and the formation of invadopodia, a crucial feature in tumour invasion. METHODS: In B16 mouse melanoma cells, FAN was downregulated and the impact on FAN on cell motility and invasion was determined using in vitro assays and in vivo animal models. RESULTS: Like FAN(-/-) murine embryonic fibroblasts, FAN-deficient B16 melanoma cells showed defective motility responses to TNF in vitro. In vivo FAN-deficient B16 melanoma cells produced significantly less disseminated tumours after i.v. injection into mice. Danio rerio used as a second in vivo model also revealed impaired spreading of FAN-deficient B16 melanoma cells. Furthermore, FAN mediated TNF-induced paxillin phosphorylation, metalloproteinase activation and increased extracellular matrix degradation, the hallmarks of functionally active invadopodia. CONCLUSION: The results of our study suggest that FAN through promoting melanoma cellular motility and tumour invasiveness is critical for the tumour-promoting action of TNF.
