组蛋白甲基化酶G9a调控NK细胞抗肿瘤功能的机制研究

Immune microenvironment plays an important role in the process of cancer development, metastasis and prognosis. Compare to T cell, NK cells could kill the tumor cells directly without previously sensitized. Therefore, achieve effective regulation of NK cell function is important for cancer intervention, change of patient life quality and improvement of clinical outcome. Small molecule inhibitor BIX01294 (Specific to histone methylation enzyme G9a) has a significant anticancer function under physiological conditions. However, the effect of BIX01294 on the immune system, especially for the effect on NK cells, is rarely studied. In our previous study, we first found that histone methylation enzyme G9a plays a vital role in the killing of tumor cells by NK cells. In this project，we will thoroughly investigate the critical step in NK cell cytotoxicity influenced by G9a through different experimental system in human NK cell line. What’s more, we will discover the downstream key regulators by high throughput sequencing. Finally, we further study the mechanism of histone methyltransferase G9a in NK cell cytotoxicity in human peripheral blood NK cell and conditional knock-out mice. The aim of this project is to explore the molecular mechanism that small molecule inhibitor BIX01294 regulate the antitumor activity of NK cells and provide new regulatory targets for the clinical application of NK cells in the field of immunotherapy.

免疫微环境在癌症的发生、发展、转移及预后过程中发挥重要的作用。与T细胞相比，NK细胞可以在不预敏的情况下直接杀伤肿瘤细胞，因此实现对NK细胞功能的有效调控，对于癌症干预、提高患者生存质量和改善临床结局具有重要且深远的意义。小分子抑制剂BIX01294（抑制组蛋白甲基化酶G9a）在生理条件下有抗癌功能，而BIX01294对免疫系统的影响，尤其是NK细胞的影响还鲜有研究。本课题组的前期研究首次发现BIX01294可以促进NK细胞抗肿瘤的能力。本课题拟在前期研究基础上，找到BIX01294影响NK细胞杀伤靶细胞的关键步骤；与此同时，结合高通量手段，明确G9a直接调控的基因；最后，利用人外周血NK细胞和G9a条件敲除小鼠为研究对象，进一步阐明G9a调控NK细胞活性的机制。本项目旨在探索G9a调控NK细胞抗肿瘤活性的分子机制，为NK细胞在免疫治疗领域的临床应用提供新的调控靶点和数据支持。

现阶段抗癌治疗策略的主要障碍是肿瘤细胞的免疫逃避。而免疫逃避的主要机制包括改变免疫细胞杀死癌细胞的速度和功效。NK细胞具有非特异性识别和杀死癌细胞的能力，无需预敏化，在免疫监视中发挥着重要作用。因此实现对NK细胞抗肿瘤功能的有效调控，对于癌症干预、提高患者生存质量和改善临床结局具有重要且深远的意义。组蛋白甲基化修饰具备特异性和可逆性的特点，使得组蛋白甲基化酶成为了理想的药物靶点。本课题利用NK92MI细胞系、人外周血NK细胞和G9a条件敲除小鼠为研究对象，经过3年的研究明确了：抑制G9a活性或者特异性敲除G9a的表达可以上调NK细胞中IFN-γ的表达水平、促进NK细胞的终末成熟过程并提高NK细胞的免疫监控能力。