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MiR-21 depletion in macrophages promotes tumoricidal polarization and enhances PD-1 immunotherapy.

ABSTRACT: MicroRNA-21 (miR-21) is one of the most abundant microRNAs in mammalian cells. It has been intensively studied for its role in regulating apoptosis and oncogenic transformation. However, the impact of miR-21 on host anti-tumor immunity remains unknown. Tumor-associated macrophages are a major leukocyte type that infiltrates tumors and predominantly develops into immunosuppressive, tumor-promoting M2-like macrophages. In contrast, the pro-inflammatory M1-like macrophages have tumoricidal activity. In this study, we show that genetic deficiency of miR-21 promotes the polarization of macrophages toward an M1-like phenotype in vivo and in vitro in the presence of tumor cells; thus it confers host mice with enhanced anti-tumor immunity. By downregulating JAK2 and STAT1, miR-21 inhibits the IFN-?-induced STAT1 signaling pathway, which is required for macrophage M1 polarization. We also show that the expression of miR-21 in macrophages is regulated upon polarization stimuli as well as upon macrophages co-culturing with tumor cells. Thus, tumor cells may stimulate miR-21 expression in tumor-associated macrophages to prevent tumoricidal M1 polarization. However, augmented STAT1 signaling mediated by miR-21 deficiency upregulates PD-L1 expression in macrophages, which is known to inhibit phagocytic anti-tumor activity. This adverse effect can be alleviated by PD-1 blockade; indeed, miR-21 depletion in macrophages and PD-1 antibody treatment offer superior anti-tumor activity than either agent alone. These studies shed lights on potential application of the combination of miR-21 inhibition and immune checkpoint blockade to target the tumor microenvironment.

SUBMITTER: Xi J

PROVIDER: S-EPMC5993583 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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miR-21 depletion in macrophages promotes tumoricidal polarization and enhances PD-1 immunotherapy.

Xi Jiajia J Huang Qian Q Wang Lei L Ma Xiaodong X Deng Qipan Q Kumar Munish M Zhou Zhiyuan Z Li Ling L Zeng Zhaoyang Z Young Ken H KH Zhang Mingzhi M Li Yong Y

Oncogene 20180315 23

MicroRNA-21 (miR-21) is one of the most abundant microRNAs in mammalian cells. It has been intensively studied for its role in regulating apoptosis and oncogenic transformation. However, the impact of miR-21 on host anti-tumor immunity remains unknown. Tumor-associated macrophages are a major leukocyte type that infiltrates tumors and predominantly develops into immunosuppressive, tumor-promoting M2-like macrophages. In contrast, the pro-inflammatory M1-like macrophages have tumoricidal activity ...[more]

PMID: 29540832

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Project description:BackgroundAlthough anti-programmed cell death protein 1 (PD-1) immunotherapy is greatly effective in melanoma treatment, low response rate and treatment resistance significantly hinder its efficacy. Tumor cell ferroptosis triggered by interferon (IFN)-γ that is derived from tumor-infiltrating CD8+ T cells greatly contributes to the effect of immunotherapy. However, the molecular mechanism underlying IFN-γ-mediated ferroptosis and related potentially promising therapeutic strategy warrant further clarification. MicroRNAs (miRNAs) participate in ferroptosis execution and can be delivered systemically by multiple carriers, which have manifested obvious therapeutic effects on cancer.MethodsMiRNAs expression profile in IFN-γ-driven ferroptosis was obtained by RNA sequencing. Biochemical assays were used to clarify the role of miR-21-3p in IFN-γ-driven ferroptosis and the underlying mechanism. MiR-21-3p-loaded gold nanoparticles were constructed and systemically applied to analyze the role of miR-21-3p in anti-PD-1 immunotherapy in preclinical transplanted tumor model.ResultsMiRNAs expression profile of melanoma cells in IFN-γ-driven ferroptosis was first obtained. Then, upregulated miR-21-3p was proved to facilitate IFN-γ-mediated ferroptosis by potentiating lipid peroxidation. miR-21-3p increased the ferroptosis sensitivity by directly targeting thioredoxin reductase 1 (TXNRD1) to enhance lipid reactive oxygen species (ROS) generation. Furthermore, miR-21-3p overexpression in tumor synergized with anti-PD-1 antibody by promoting tumor cell ferroptosis. More importantly, miR-21-3p-loaded gold nanoparticles were constructed, and the systemic delivery of them increased the efficacy of anti-PD-1 antibody without prominent side effects in preclinical mice model. Ultimately, ATF3 was found to promote miR-21-3p transcription in IFN-γ-driven ferroptosis.ConclusionsMiR-21-3 p upregulation contributes to IFN-γ-driven ferroptosis and synergizes with anti-PD-1 antibody. Nanoparticle delivery of miR-21-3 p is a promising therapeutic approach to increase immunotherapy efficacy without obvious systemic side effects.

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MiR-21 depletion in macrophages promotes tumoricidal polarization and enhances PD-1 immunotherapy.

Publications

miR-21 depletion in macrophages promotes tumoricidal polarization and enhances PD-1 immunotherapy.

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