Abstract Radiotherapy is an important component of the therapeutics for cancer. Although the primary objective of RT is the local control of tumors, RT-mediated antitumor adaptive immunity is emerging as a promising tool in cancer treatment. Increasing evidence indicates that RT enhances adaptive anti-tumor immunity by augmenting the innate immune sensing of tumors in a type I IFN-dependent matter. Both retinoic acid-related orphan receptor α (RORα) and nuclear heme receptor Rev-erbα, are core components of the circadian rhythm, all have critical roles in inflammation and immune process. Our preliminary data showed that both RORα inverse agonist (antagonist) SR1001 and Rev-erbα agonist GSK4112 significantly enhanced radiation-induced type I IFN activation. We also found that both RORα and Rev-erbα could associate with IRF3 and regulate IRF3 phosphorylation, which enhance radiation-induced type I IFN activation. Furthermore, our data indicated that radiation induced Type I IFN production may depend on circadian cycle, and SR1001 treatment contribute to antitumor immunity of radiation. These results usher the hypothesis that RORα/Rev-erbα work together to regulate radiation-induced type I IFN response, and contribute to antitumor immunity of RT. Specifically, our data shown the critical role of RORα/Rev-erbα/IRF3 axis in regulating radiation-induced type I IFN activation and targeting RORα/Rev-erbα will synergize with radiotherapy. Altogether, the preliminary data generated from this proposal opens additional avenues of research, both preclinically and clinically, to help better understand the relationship of the circadian rhythm proteins on the RT-immune response. Citation Format: Nan LI, Chen Bruan, Steven Hsesheng Lin. Targeting REV-ERB/RORα/IRF3 axis to enhance radiation-induced immune response in cancer radiotherapy. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr B006.
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