TRAIL signaling is mediated by DR4 in pancreatic tumor cells despite the expression of functional DR5.
Tumor necrosis factor related apoptosis-inducing ligand (TRAIL) and agonistic anti-DR4/TRAIL-R1 and anti-DR5/TRAIL-R2 antibodies are currently under clinical investigation for treatment of different malignancies. TRAIL activates DR4 and DR5 and thereby triggers apoptotic and non-apoptotic signaling pathways, but possible different roles of DR4 or DR5 in these responses has poorly been addressed so far. In the present work, we analyzed cell viability, DISC formation as well as IL-8 and NF-kappaB activation side by side in responses to TRAIL and agonistic antibodies against DR4 (mapatumumab) and against DR5 (lexatumumab) in pancreatic ductal adenocarcinoma cells. We found that all three reagents are able to activate cell death and pro-inflammatory signaling. Death-inducing signaling complex (DISC) analysis revealed that mapatumumab and lexatumumab induce formation of homocomplexes of either DR4 or DR5, whereas TRAIL additionally stimulated the formation of heterocomplexes of both receptors. Notably, blocking of receptors using DR4- and DR5-specific Fab fragments indicated that TRAIL exerted its function predominantly via DR4. Interestingly, inhibition of PKC by Goe6983 enabled DR5 to trigger apoptotic signaling in response to TRAIL and also strongly enhanced lexatumumab-mediated cell death. Our results suggest the existence of mechanisms that silence DR5 for TRAIL- but not for agonistic-antibody treatment.
Lemke
Johannes
J
Division of Molecular Oncology, Institute of Experimental Cancer Research, Comprehensive Cancer Center North, UK S-H, Arnold-Heller Str. 3, Haus 17, 24 105 Kiel, Germany.
Noack
Andreas
A
Adam
Dieter
D
Tchikov
Vladimir
V
Bertsch
Uwe
U
Röder
Christian
C
Schütze
Stefan
S
Wajant
Harald
H
Kalthoff
Holger
H
Trauzold
Anna
A
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D061067:Antibodies, Monoclonal, Humanized; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000378:metabolism; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D019169:Jurkat Cells; D016328:NF-kappa B / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D004791:Enzyme Inhibitors; D007140:Immunoglobulin Fab Fragments; D016209:Interleukin-8; D016328:NF-kappa B; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C510234:lexatumumab; D011493:Protein Kinase C; C507357:mapatumumab