Abstract
The death receptor (DR) ligand TRAIL is being evaluated in clinical trials as an anti-cancer agent; however, many studies have found that TRAIL also enhances tumor progression by activating the NF-κB pathway in apoptosis-resistant cells. Although RIP1, cFLIP and caspase-8 have been implicated in TRAIL-induced JNK and NF-κB activation, underlying mechanisms are unclear. By examining the kinetics of pathway activation in TRAIL-sensitive lymphoma cells wild-type or deficient for RIP1, TRAF2, cIAP1/2 or HOIP, we report here that TRAIL induces two phases of JNK and NF-κB activation. The early phase is activated by TRAF2- and cIAP1-mediated ubiquitination of RIP1, whereas the delayed phase is induced by caspase-dependent activation of MEKK1 independent of RIP1 and TRAF2 expression. cFLIP overexpression promotes the early phase but completely suppresses the delayed phase of pathway activation in lymphoma cells, whereas Bcl-2 overexpression promotes both the early and delayed phases of the pathways. In addition, stable overexpression of cFLIP in RIP1- or TRAF2-deficient cells confers resistance to apoptosis, but fails to mediate NF-κB activation. HOIP is not essential for, but contributes to, TRAIL-induced NF-κB activation in cFLIP-overexpressing cells. These findings not only elucidate details of the mechanisms underlying TRAIL-induced JNK and NF-κB activation, but also clarify conflicting reports in the field.
Keywords:
Apoptosis; Caspase-8; NF-κB; RIP1; TRAIL; cFLIP.
Copyright © 2014 Elsevier Inc. All rights reserved.
Publication types
-
Research Support, N.I.H., Extramural
MeSH terms
-
Baculoviral IAP Repeat-Containing 3 Protein
-
CASP8 and FADD-Like Apoptosis Regulating Protein / genetics
-
CASP8 and FADD-Like Apoptosis Regulating Protein / metabolism
-
Cell Line, Tumor
-
HEK293 Cells
-
Humans
-
I-kappa B Kinase / genetics
-
I-kappa B Kinase / metabolism
-
Inhibitor of Apoptosis Proteins / metabolism
-
JNK Mitogen-Activated Protein Kinases / metabolism*
-
Jurkat Cells
-
MAP Kinase Kinase Kinase 1 / metabolism
-
NF-kappa B / metabolism*
-
Nuclear Pore Complex Proteins / deficiency
-
Nuclear Pore Complex Proteins / genetics
-
Nuclear Pore Complex Proteins / metabolism*
-
RNA-Binding Proteins / genetics
-
RNA-Binding Proteins / metabolism*
-
Recombinant Proteins / biosynthesis
-
Recombinant Proteins / genetics
-
Recombinant Proteins / pharmacology
-
Signal Transduction / drug effects*
-
TNF Receptor-Associated Factor 2 / metabolism
-
TNF-Related Apoptosis-Inducing Ligand / genetics
-
TNF-Related Apoptosis-Inducing Ligand / metabolism
-
TNF-Related Apoptosis-Inducing Ligand / pharmacology*
-
Transcriptional Activation / drug effects
-
Ubiquitin-Protein Ligases / metabolism
-
Ubiquitination / drug effects
Substances
-
AGFG1 protein, human
-
CASP8 and FADD-Like Apoptosis Regulating Protein
-
Inhibitor of Apoptosis Proteins
-
NF-kappa B
-
Nuclear Pore Complex Proteins
-
RNA-Binding Proteins
-
Recombinant Proteins
-
TNF Receptor-Associated Factor 2
-
TNF-Related Apoptosis-Inducing Ligand
-
BIRC3 protein, human
-
Baculoviral IAP Repeat-Containing 3 Protein
-
Ubiquitin-Protein Ligases
-
I-kappa B Kinase
-
JNK Mitogen-Activated Protein Kinases
-
MAP Kinase Kinase Kinase 1