Samenvatting
Objective: When Second mitochondria-derived activator of caspases (Smac) is released into the cytosol, it efficiently promotes apoptosis by antagonizing inhibitor of apoptosis proteins (IAP). In this study, we evaluated whether lentiviral delivery of a truncated version of Smac (tSmac) to melanoma cells induces apoptosis and whether this tSmac-induced apoptosis acts as a pro-inflammatory signal for antigen presenting cells, hence boosts anti-tumour immune responses.
Methods: Induction of apoptosis upon transduction of tumour cells (murine melanoma cells expressing ovalbumin; MO4 cell line) with lentiviruses encoding tSmac (LV-tSmac) was determined by flow cytometry. Subcutaneous tumours (B57/Bl6) were transduced in vivo and the induced immune response was measured by an in vivo CTL assay and by the analysis of the tumour infiltrating T cells.
Results: We demonstrated that tSmac encoding lentiviruses induce apoptosis of mouse melanoma cells in vitro. Intratumoral injection of LV-tSmac resulted in delayed tumour growth due to the induction of apoptosis in vivo as well as by the activation of the immune system. The dendritic cells (DCs) isolated from tumour draining lymph nodes were able to activate OVA-specific CD8+ T cells. The induction of an OVA-specific CTL response could be demonstrated. Analysis of the treated tumour showed an increase of infiltrating effector T cells and the decrease of regulatory T cells.
Transduction of human melanoma cells with LV in which expression of tSmac is driven by the tyrosinase promoter also resulted in apoptosis. Monocyte-derived DCs exposed to these apoptotic bodies upregulated their costimulatory surface molecules and presented melanoma derived antigens to a specific T cell clone.
Conclusion: Lentiviruses encoding tSmac induce apoptosis and simultaneously deliver pro-inflammatory signals that boost anti-tumour immune responses.
Methods: Induction of apoptosis upon transduction of tumour cells (murine melanoma cells expressing ovalbumin; MO4 cell line) with lentiviruses encoding tSmac (LV-tSmac) was determined by flow cytometry. Subcutaneous tumours (B57/Bl6) were transduced in vivo and the induced immune response was measured by an in vivo CTL assay and by the analysis of the tumour infiltrating T cells.
Results: We demonstrated that tSmac encoding lentiviruses induce apoptosis of mouse melanoma cells in vitro. Intratumoral injection of LV-tSmac resulted in delayed tumour growth due to the induction of apoptosis in vivo as well as by the activation of the immune system. The dendritic cells (DCs) isolated from tumour draining lymph nodes were able to activate OVA-specific CD8+ T cells. The induction of an OVA-specific CTL response could be demonstrated. Analysis of the treated tumour showed an increase of infiltrating effector T cells and the decrease of regulatory T cells.
Transduction of human melanoma cells with LV in which expression of tSmac is driven by the tyrosinase promoter also resulted in apoptosis. Monocyte-derived DCs exposed to these apoptotic bodies upregulated their costimulatory surface molecules and presented melanoma derived antigens to a specific T cell clone.
Conclusion: Lentiviruses encoding tSmac induce apoptosis and simultaneously deliver pro-inflammatory signals that boost anti-tumour immune responses.
| Originele taal-2 | English |
|---|---|
| Titel | First PhD day of the Medical Campus VUB. Brussels, Belgium |
| Status | Published - 5 apr 2011 |