The chemotherapeutic agent DMXAA potently and specifically activates the TBK1-IRF-3 signaling axis.
Vascular disrupting agents (VDAs) represent a novel approach to the treatment of cancer, resulting in the collapse of tumor vasculature and tumor death. 5,6-dimethylxanthenone-4-acetic acid (DMXAA) is a VDA currently in advanced phase II clinical trials, yet its precise mechanism of action is unknown despite extensive preclinical and clinical investigations. Our data demonstrate that DMXAA is a novel and specific activator of the TANK-binding kinase 1 (TBK1)-interferon (IFN) regulatory factor 3 (IRF-3) signaling pathway. DMXAA treatment of primary mouse macrophages resulted in robust IRF-3 activation and approximately 750-fold increase in IFN-beta mRNA, and in contrast to the potent Toll-like receptor 4 (TLR4) agonist lipopolysaccharide (LPS), signaling was independent of mitogen-activated protein kinase (MAPK) activation and elicited minimal nuclear factor kappaB-dependent gene expression. DMXAA-induced signaling was critically dependent on the IRF-3 kinase, TBK1, and IRF-3 but was myeloid differentiation factor 88-, Toll-interleukin 1 receptor domain-containing adaptor inducing IFN-beta-, IFN promoter-stimulator 1-, and inhibitor of kappaB kinase-independent, thus excluding all known TLRs and cytosolic helicase receptors. DMXAA pretreatment of mouse macrophages induced a state of tolerance to LPS and vice versa. In contrast to LPS stimulation, DMXAA-induced IRF-3 dimerization and IFN-beta expression were inhibited by salicylic acid. These findings detail a novel pathway for TBK1-mediated IRF-3 activation and provide new insights into the mechanism of this new class of chemotherapeutic drugs.
Roberts
Zachary J
ZJ
Department of Microbiology and Immunology, University of Maryland-Baltimore, Baltimore, MD 21201, USA.
Goutagny
Nadege
N
Perera
Pin-Yu
PY
Kato
Hiroki
H
Kumar
Himanshu
H
Kawai
Taro
T
Akira
Shizuo
S
Savan
Ram
R
van Echo
David
D
Fitzgerald
Katherine A
KA
Young
Howard A
HA
Ching
Lai-Ming
LM
Vogel
Stefanie N
SN
D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use; D002478:Cells, Cultured; D016207:Cytokines / Q000032:analysis; D004247:DNA / Q000235:genetics; D004742:Enhancer Elements, Genetic; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007147:Immunoglobulin Light Chains / Q000235:genetics; D050838:Interferon Regulatory Factor-3 / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D044004:Xanthones / Q000627:therapeutic use*
D000970:Antineoplastic Agents; D016207:Cytokines; D007147:Immunoglobulin Light Chains; D050838:Interferon Regulatory Factor-3; D044004:Xanthones; C066668:vadimezan; D004247:DNA; D011494:Protein Kinases; C498588:Tbk1 protein, mouse; D017346:Protein Serine-Threonine Kinases