The chemotherapeutic agent DMXAA potently and specifically activates the TBK1–IRF-3 signaling axis

Abstract

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 ∼750-fold increase in IFN-β 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 κB–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-β–, IFN promoter-stimulator 1–, and inhibitor of κB 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-β 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.

Tumor stress, cell death and the ensuing immune response

“…DMXAA acts on the TANK-binding kinase 1-interferon (IFN) regulatory factor 3 (IRF-3) signaling pathway. 73 These findings suggest that the activation of tumor-associated macrophages with DMXAA could be a critical step to promote the recruitment and/or re-activation of tumor-specific CD8 þ T cells. A similar scenario can be proposed for TLR3 agonists.…”

Interferon Stimulated Gene - ISG15 is a Potential Diagnostic Biomarker in Oral Squamous Cell Carcinomas

“…While the expression and activation of both NFκB and IRF3 are high in host cells challenged with microbial infections, IRF3 is also induced in response to chemotherapeutic agents (Roberts et al, 2007) independent of IFNs. Since none of the OSCC patients, who were included in the present study had any microbial infections or were under chemotherapy, the possibility of IRF3 mediated overexpression of ISG15 in the twenty four samples may be ruled out.…”

Macrophage Proinflammatory Response to Francisella tularensis Live Vaccine Strain Requires Coordination of Multiple Signaling Pathways

“…6). The efficacy of a potent IFN-␤ inducer DMXAA (21), to reduce Ft LVS bacterial burden in macrophages, was also tested. Treatment of Ft LVS-infected macrophages with DMXAA reduced bacterial burden ϳ10-fold within 24 h and ϳ100-fold by 48 h (Fig.…”