Comparative analysis of dendritic cells transduced with different anti-apoptotic molecules: sensitivity to
Levent Balkir1, Irina L Tourkova, Valeria P Makarenkova
1Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Background:
Tumors develop mechanisms to escape recognition by the immune system. It has recently been demonstrated that tumors cause apoptotic death of key immune cells, including the major antigen-presenting cells, dendritic cells (DC). Elimination of DC from the tumor environment significantly diminishes development of specific immunologic responses. We have recently demonstrated that tumor-induced DC apoptosis could be prevented by overexpression of the anti-apoptotic molecule Bcl-x(L). The aim of this study was to identify extrinsic and intrinsic tumor-induced apoptotic pathways in DC by targeting different anti-apoptotic molecules, including FLIP, XIAP/hILP, dominant-negative procaspase-9 and HSP70.
Methods:
Murine bone marrow derived DC were transduced with adenoviral vectors carrying different anti-apoptotic molecules and co-incubated with tumor cells in a Transwell system. Apoptosis of DC was assessed by Annexin V and PI staining.
Results:
We have demonstrated that adenoviral infection of DC with genes encoding different anti-apoptotic molecules exhibits different degrees of resistance to melanoma-induced apoptosis. Furthermore, we have shown that anti-apoptotic molecules other than the Bcl-2 family of proteins are able to protect DC and prevent tumor-induced apoptosis in DC.
Conclusions:
The results show that tumor-induced apoptosis of DC is not limited to the mitochondrial pathway of cell death and open additional possibilities for targeted molecular protection of DC longevity in cancer. Therefore, effective protection of DC from tumor-induced apoptosis may significantly improve the efficacy of DC-based therapies for cancer.
Insights
Tumors induce dendritic cell (DC) apoptosis, hindering immune responses. This study shows that targeting various anti-apoptotic molecules, beyond Bcl-2, can protect DCs from tumor-induced death, improving cancer therapies.
Area of Science:
- Immunology
- Cancer Biology
- Molecular Cell Biology
Background:
- Tumors evade immune detection through mechanisms like inducing apoptosis in immune cells.
- Tumor-induced apoptosis of dendritic cells (DCs), crucial antigen-presenting cells, impairs anti-tumor immunity.
- Previous work showed Bcl-x(L) overexpression prevents tumor-induced DC apoptosis.
Purpose of the Study:
- To identify extrinsic and intrinsic tumor-induced apoptotic pathways in DCs.
- To evaluate the protective effects of various anti-apoptotic molecules against tumor-induced DC apoptosis.
Main Methods:
- Murine bone marrow-derived DCs were transduced with adenoviral vectors encoding anti-apoptotic molecules.
- Transduced DCs were co-incubated with tumor cells in a Transwell system.
- Apoptosis was assessed using Annexin V and Propidium Iodide (PI) staining.
Main Results:
- Different anti-apoptotic molecules conferred varying degrees of resistance to melanoma-induced DC apoptosis.
- Anti-apoptotic molecules outside the Bcl-2 family effectively protected DCs from tumor-induced apoptosis.
- This suggests multiple pathways are involved in tumor-induced DC apoptosis.
Conclusions:
- Tumor-induced DC apoptosis involves pathways beyond the mitochondrial route.
- Targeting specific anti-apoptotic molecules offers novel strategies for preserving DC function in cancer.
- Protecting DCs from apoptosis can enhance the efficacy of DC-based cancer immunotherapies.
