IL-6对乳腺癌转移相关蛋白MTA1的调控及其在免疫治疗中的应用研究

The metastasis of cancer is one of the most important reason that leads to the mortality. IL-6 can reach to a higher concentration in the breast cancer microenvironment and the serum of the patients, and can promote the metastasis. In the preliminary studies, we firstly discovered that IL-6 could upregulate the expression of the metastasis assiciated protein 1 (MTA1), but the mechnism remains unclear. Therefore, we proposed to study the regulation mechanism of IL-6 on MTA1 in breast cancer metastasis, and study its application in tumor immunology. siRNA and STAT3 inhibitor will be used to study the regulation pathway of IL-6 on MTA1. Chromatin immunoprecipitation and luciferase reporter gene assays will be performed to identify the binding of STAT3 and the promoter of MTA1. The expression of downstream key genes will be tested by western blot assay. The relation between the expression of STAT3 and MTA1, and the metastasis grade will be analyzed by the breast cancer specimens collected. At last, the xenograft tumor and metastasis model in mice will be performed to study the immunotheraputic effects of combination of MTA1 immunization, and STAT3 inhibitor or chemotherapy. Our results will provide important theoretic support to the breast cancer metastasis, and will provide novel ideas to the immunotherapy of breast cancer.

肿瘤的转移是导致患者死亡的重要原因。IL-6在乳腺癌组织微环境以及患者的血清中可以达到较高的浓度，并且能够促进乳腺癌细胞的转移。我们前期首次发现IL-6能够上调乳腺癌细胞中转移相关蛋白MTA1的表达，但其机制尚不清楚。因此，本项目拟研究IL-6对MTA1的调控机制以及在乳腺癌转移中的作用，并探讨该机制在肿瘤免疫治疗中的应用。通过siRNA干扰技术和STAT3抑制剂研究IL-6对MTA1的调控通路，通过染色质免疫沉淀和荧光素酶报告基因实验证明STAT3与MTA1启动子的结合，利用Western blot实验对下游的关键蛋白的表达进行分析；收集临床标本对MTA1和STAT3与乳腺癌转移的相关性进行研究；最后，通过小鼠荷瘤和转移模型探讨MTA1免疫联合STAT3阻断剂以及化疗药物的免疫治疗效果。我们的研究结果将为乳腺癌的转移机制研究提供重要的理论支持，并将为乳腺癌的免疫治疗方法提供新的思路。

IL-6可以导致乳腺癌的转移，但其作用机制尚未阐明。在本项目中，我们发现IL-6可以上调MTA1进而促进乳腺癌的转移，IL-6/STAT3通路可以上调MTA1的表达；为了更深入的探讨是否还有其它基因参与了这个过程，我们构建了稳定表达IL-6的MCF-7细胞系和敲除IL-6的MDA-MB-231细胞系，通过RNA-Seq筛选了IL-6影响乳腺癌转移的基因，通过体内外实验和临床病例分析，发现IL-6的表达水平与乳腺癌的转移正相关，与病人的预后呈现负相关，在ER阴性的肿瘤组织中表达高于ER阳性，通过功能验证和体内外转移实验分析发现，沉默EPAS1和CDKN1A能够抑制乳腺癌的转移；此外，我们还鉴定了来自MTA1的鉴定了CTL表位和具有免疫活性的关键蛋白片段，能够诱导特异性杀伤肿瘤细胞的CTL，我们还发现多种化疗药物处理时MTA1表达均上调。该研究为深入的理解IL-6促进乳腺癌的转移提供了重要的数据支持，为基于MTA1的免疫治疗和化疗的联用打下了基础。