IFN-γ通过EZH2介导lncRNA调控肝癌中枯否细胞表达Galectin-9的机制

Our previous study have demonstrated that Tim-3/Galectin-9 signaling pathway highly expresses in hepatocellular carcinoma, and involved in immune escape. Recent studies mostly focused on mechanisms of Tim-3 intracellular signal transduction, but few research worked on Galectin-9. Our preliminary result showed: (1) IFN-γ could induce Galectin-9 expression on Kupffer cells. (2) There are obvious difference of lncRNA expression between Galectin-9 negative and positive Kupffer cells by using Affymetrix lncRNA Array. (3) IFN-γ induce Kupffer cells highly expressing EZH2. Basing on the results, we suppose there is a IFN-γ — EZH2 — lncRNA — Galectin-9 axis, and suggest that this axis could be a potential immunotherapeutic target in patients with HCC.

我们研究已证明，Tim-3/Galectin-9信号通路肝癌中高表达并介导免疫逃逸，近年来的研究多集中于Tim-3的胞内信号转导机制研究，对于Galectin-9的研究鲜有涉及，本项目初步证实：肝癌微环境中丰富的IFN-γ可以刺激Kupffer细胞高表达Galectin-9，利用lncRNA表达芯片筛查Galectin-9-Kupffer细胞与Galectin-9+Kupffer细胞存在lncRNA表达谱差异，并且发现在诱导过程中Kupffer细胞内EZH2表达也同步增加，而EZH2多是通过甲基化沉默基因表达，我们提出了IFN-γ — EZH2 — lncRNA — Galectin-9调节轴的概念，若本项目证实了该调节轴的存在，则将解释肝癌微环境中Galectin-9高表达机制，为肝癌的的免疫治疗提供新的靶点。

近年来已有不少文献报道在肝细胞癌中IFN-Y可以诱导Kupffer细胞表达galectin-9从而在肿瘤微环境中发挥重要作用，然而IFN-Y可否刺激肝癌细胞表达galectin-9以及其在肝癌的发展及预后中的作用仍未明确。我们利用RTPCR检测经过IFN-Y刺激后的肝癌细胞中galectin-9和EZH2的表达量变化，发现两者明显增高；通过生物学软件预测结合双荧光素酶报告基因检测分析我们发现miR-22可以结合与galectin-9的3’-UTR端，经过MSP极速BSP检测确定miR-22基因启动子区域存在甲基化，最后经由CHIP证实了正是EZH2介导了miR-22基因启动子区域组蛋白H3K27me3的甲基化改变。随后在细胞水平及体外动物模型我们证实了miR-22和galectin-9皆表现出肿瘤抑制效应。