Comparative analysis of dendritic cells transduced with different anti-apoptotic molecules: sensitivity to tumor-induced apoptosis.
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.
Balkir
Levent
L
Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Tourkova
Irina L
IL
Makarenkova
Valeria P
VP
Shurin
Galina V
GV
Robbins
Paul D
PD
Yin
Xiao-Ming
XM
Chatta
Gurkamal
G
Shurin
Michael R
MR
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis; D001854:Bone Marrow Cells / Q000378:metabolism; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D053453:Caspase 9; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival; D003713:Dendritic Cells / Q000378:metabolism*; D005822:Genetic Vectors; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008545:Melanoma; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000502:physiology; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506387:Cflar protein, mouse; D018840:HSP70 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; C506434:Casp9 protein, mouse; D053453:Caspase 9; D020169:Caspases