Toll-Like Receptor-4 Antagonist Enhances the Repair of Ultraviolet Radiation-Induced DNA Damage and Augments Anti-Tumor Immune Responses in Mice

Abstract

Ultraviolet (UV) irradiation of the skin is related to the development of skin cancer. UVB also causes DNA damage in the form of cyclobutane pyrimidine dimers (CPDs), which can result in stable mutations. Toll-like receptor 4 (TLR4), a component of innate immunity, plays a key role in cancer. Previous studies from our laboratory have observed that TLR4 deficiency resulted in the repair of UVB-induced DNA damage, inhibition of UVB-induced immune suppression, and carcinogenesis. In this study, we determined the efficacy of TLR4 antagonist TAK-242 in regulation of UVB-induced DNA damage, inflammation, and tumor development. Our results indicate that TAK-242 treatment increased the expression of xeroderma pigmentosum group A (XPA) mRNA, resulting in the repair of UVB-induced CPDs in skin of SKH-1 mice. Treatment with TAK-242 also inhibited the activation of NLR family pyrin domain containing 3 (NLRP3) in UVB-exposed skin of SKH-1 mice. Cutaneous carcinogenesis was significantly reduced in mice treated with TAK-242 in comparison to vehicle-treated mice. The proinflammatory cytokines IL-1β, IL-6, and TNF-α were also found to be significantly greater in vehicle-treated mice than TAK-242-treated mice. Finally, treatment with TAK-242 augmented anti-tumor immune responses in mice. Our data provide further evidence that activation of the TLR4 pathway promotes the development of UV-induced non-melanoma skin cancer mediated at least in part on its negative effects on DNA damage. Moreover, treatment with the TLR4 inhibitor TAK-242 may be effective for prevention of skin cancer.

Polymorphisms in toll-like receptor 3 and 4 genes as prognostic and outcome biomarkers in melanoma patients

“…Malignant transformation of melanocytes is a very complex, multi-step process that involves several genes orchestrating cell proliferation, differentiation, apoptosis and antitumor immune responses [1,2]. The accumulation of genetic changes, including UV-driven mutation burdens, makes melanoma a highly immunogenic tumor, suitable for immunotherapy [17][18][19]. However, due to insufficient immune activation, patients show variable response rates to immunotherapy.…”

“…Also, deubiquitinating enzyme tripartite motif-containing protein 44 (TRIMM44) promotes melanoma progression via TLR4 stabilization, which subsequently activates the phosphoinositide 3-kinase-AKT-mammalian target of rapamycin signaling pathway [27]. Finally, treatment with TLR4 antagonist TAK-242 amplifies antitumor immune responses in UV-induced skin cancer in mice [17].…”

“…However, due to insufficient immune activation, patients show variable response rates to immunotherapy. In the focus of immunogenic attributes of melanoma progression lie TLR signaling [17,[19][20][21]. The actual mechanisms of TLR signaling in cancer remain elusive, and only a limited number of previous studies investigated the association of TLR3 and TLR4 gene polymorphisms with melanoma progression and survival [7,14,15].…”

Small-Molecule Modulators Targeting Toll-like Receptors for Potential Anticancer Therapeutics

“…TAK-242 ( 2 , resatorvid, CLI-095), a selective TLR4 signaling inhibitor (Figure ), covalently binds to Cys747 on the intracellular domain of TLR4 via Michael reaction, disrupting the interaction between TLR4 and cohesion molecules and inhibiting NO, TNF-α, and IL-6 production, with IC 50 values of 1.8, 1.9, and 1.3 nM, respectively. , TAK-242 ( 2 ) blocks UV-induced NF-κB and MAP kinase/AP-1 activity and the expression of cytokines IL-6, IL-8, and IL-10 in cultured keratinocytes and the skin of topically treated mice, showing potential for prevention of nonmelanoma skin cancer (NMSC). , Subsequent studies demonstrated that treatment with 2 increased the level of expression of xeroderma pigmentosum group A (XPA) mRNA, resulting in the repair of UVB-induced cyclobutane pyrimidine dimers (CPDs) in the skin of SKH-1 mice. Treatment with 2 inhibited the expression of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α and enhanced the antitumor immune response in mice …”

Type I Interferons Enhance the Repair of Ultraviolet Radiation-Induced DNA Damage and Regulate Cutaneous Immune Suppression

“…Using iQ TM SYBR Green Master Mix (Bio-Rad, Hercules, CA, USA), cDNA was amplified by a real-time PCR with a Bio-Rad MyiQ thermocycler and SYBR Green detection system (Bio-Rad, Hercules, CA, USA). The standard PCR conditions were 95 • C for 10 min and then 40 cycles at 95 • C for 30 s, 60 • C for 30 s, and 72 • C for 30 s. The expression of XPA, IFNα, IFNβ, IRF1, IRF4, IRF7 gene (Table 1) was normalized to the expression level of the GAPDH mRNA in each sample (23,40,(44)(45)(46)(47)(48)(49)(50). For mRNA analysis, the calculations for determining the relative level of gene expression were made using the cycle threshold (C t ) method.…”