背景:靶向肿瘤微环境代表了一种新兴的癌症治疗策略。巨噬细胞是肿瘤微环境的重要组成部分。巨噬细胞极化由线粒体代谢调节,包括氧化磷酸化(OXPHOS),三羧酸(TCA)循环,和活性氧的含量。异柠檬酸脱氢酶2(IDH2),一种参与TCA循环的酶,据报道促进癌症进展。然而,IDH2影响巨噬细胞极化和调节肿瘤生长的机制尚不清楚.
方法:在本研究中,使用IDH2缺陷敲除(KO)小鼠和原代培养的骨髓来源的巨噬细胞(BMDM)。进行了体内皮下肿瘤实验和体外共培养实验,并收集样品进行分析。西方印迹,RNA定量分析,免疫组织化学,和流式细胞术用于确认线粒体功能的变化以及暴露于肿瘤微环境的巨噬细胞的极化。为了分析对肿瘤细胞的影响,测量皮下肿瘤大小,并鉴定了生长和转移标志物。
结果:发现与癌细胞共培养的缺乏IDH2的巨噬细胞比野生型BMDM具有增加的线粒体功能障碍和裂变。此外,M2相关标志物水平下降,而M1相关因子水平在IDH2缺陷型巨噬细胞中增加。缺乏IDH2的巨噬细胞主要是M1。IDH2缺陷小鼠组中的肿瘤大小显著小于野生型小鼠组。巨噬细胞中IDH2缺乏与抑制肿瘤生长和上皮间质转化有关。
结论:我们的研究结果表明IDH2缺乏抑制M2巨噬细胞极化并抑制肿瘤发生。这项研究强调了巨噬细胞中IDH2表达和肿瘤微环境重塑的潜在贡献。这可能对临床癌症研究有用。
BACKGROUND: Targeting the tumor microenvironment represents an emerging therapeutic strategy for cancer. Macrophages are an essential part of the tumor microenvironment. Macrophage polarization is modulated by mitochondrial metabolism, including oxidative phosphorylation (OXPHOS), the tricarboxylic acid (TCA) cycle, and reactive oxygen species content. Isocitrate dehydrogenase 2 (IDH2), an enzyme involved in the TCA cycle, reportedly promotes cancer progression. However, the mechanisms through which IDH2 influences macrophage polarization and modulates tumor growth remain unknown.
METHODS: In this study, IDH2-deficient knockout (KO) mice and primary cultured bone marrow-derived macrophages (BMDMs) were used. Both in vivo subcutaneous tumor experiments and in vitro co-culture experiments were performed, and samples were collected for analysis. Western blotting, RNA quantitative analysis, immunohistochemistry, and flow cytometry were employed to confirm changes in mitochondrial function and the resulting polarization of macrophages exposed to the tumor microenvironment. To analyze the effect on tumor cells, subcutaneous tumor size was measured, and growth and metastasis markers were identified.
RESULTS: IDH2-deficient macrophages co-cultured with cancer cells were found to possess increased mitochondrial dysfunction and fission than wild-type BMDM. Additionally, the levels of M2-associated markers decreased, whereas M1-associated factor levels increased in IDH2-deficient macrophages. IDH2-deficient macrophages were predominantly M1. Tumor sizes in the IDH2-deficient mouse group were significantly smaller than in the wild-type mouse group. IDH2 deficiency in macrophages was associated with inhibited tumor growth and epithelial-mesenchymal transition.
CONCLUSIONS: Our findings suggest that IDH2 deficiency inhibits M2 macrophage polarization and suppresses tumorigenesis. This study underlines the potential contribution of IDH2 expression in macrophages and tumor microenvironment remodeling, which could be useful in clinical cancer research.