肝细胞癌免疫检查点程序性死亡蛋白1抗体治疗获得性耐药机制及表观修饰干预研究

获得性耐药影响肝癌PD1抗体疗效。表观修饰参与肿瘤耐药等过程，但对肝癌PD1抗体获得性耐药的作用及机制不详。我们发现TET2失稳可致癌（Nature）；肝癌PDL1表达受基因等影响（Theranostics），联合mTOR或MET抑制剂可改善PD1抗体效果（Hepatology，Gastroenterology）。预实验：小鼠肝癌PD1单抗易致获得性耐药，而联用LSD1抑制剂肿瘤不复发；LSD1缺失上调肝癌PDL1和促进CD8+T细胞浸润。我们猜测：表观修饰酶调节肿瘤基因表达和/或重塑微环境阻止/逆转肝癌PD1单抗获得性耐药。拟在前期基础上利用ChIP/RNA-seq等在组织水平建立PDL1、表观修饰酶和肝癌预后关系；细胞水平探讨表观修饰酶缺失对肿瘤和免疫细胞影响；动物水平分析表观修饰酶缺失对肿瘤和微环境影响；由此揭示表观修饰酶阻止/逆转获得性耐药分子机制，为肝癌PD1单抗治疗提供新策略。

Acquired resistance is a main obstacle for the use of anti-PD1 immune therapy in patients with hepatocellular carcinoma (HCC). It is well established that epigenetic modification is involved in several processes including tumor development, tumor progression and drug resistance. But the role of epigenetic modification in acquired resistance of anti-PD1 (programmed cell death protein 1) immune therapy for patients with HCC remains unknown. In our previous studies, we showed that the instability of TET2 protein could result in the tumorigenesis (published in Nature, 2018). The level of PD-L1 (programmed cell death-ligand 1) expression in HCC cells was is affected by genes mutation (published in Theranostics, 2018). Combination of anti-PD1 antibody with mTOR inhibitor or MET inhibitors showed better efficiency in tumor control than anti-PD1 antibody or mTOR inhibitor or MET inhibitors alone (published in Hepatology, 2018; Gastroenterology, 2019). Our preliminary experiment showed that anti-PD1 antibody could efficiently inhibit the tumor growth of HCC cells. However, acquired resistance of anti-PD1 immune therapy in mouse liver cancer model was observed. Combination of anti-PD1 antibody with LSD1 (histone lysine demethylases) inhibitor could prevent from tumor relapse. Meanwhile, LSD1 inhibition could up-regulate the level of PD-L1 expression of liver cancer and promote the infiltration of CD8 positive T cell in xenografts. Thus, we hypothesize that epigenetic modification prevents and/or reverses the acquired resistance of anti-PD1 immune therapy by regulating the gene expression of tumor cell and/or remodeling tumor microenvironment of HCC. In order to testify our notion, we employed several technologies, such as ChIP/RNA-seq to do experiments as follow: (1) We will investigate the relationship between PD-L1 expression, the expression of epigenetic modification enzymes and the prognosis of patients with HCC in clinical settings; (2) We will explore the role of deletion of epigenetic modification enzyme in tumor cells and immune cells; (3) We will reveal the role of the deletion of epigenetic modification enzyme in tumor growth and tumor microenvironment; and (4) We will uncover the the molecular mechanism of acquired resistance in HCCs and the blockage and/or reversal of acquired resistance of anti-PD1 immune therapy by epigenetic modification, thus providing a new strategy for anti-PD1 immune therapy for patients with HCC.