靶向蛋白质精氨酸甲基转移酶1治疗肝癌的作用及机制探讨

Liver cancer is a kind of tumors with high incidence, but the new targeted medicines used in hepatoma therapy is deficient at present. Previous studies showed protein arginine methyltransferases 1(PRMT1) is closely related with the proliferation and metastasis of tumors, however, the effect and mechanism of PRMT1 in the progress of HCC is still not clarified. Our previous data suggested PRMT1 expression level was significantly up-regulation in HCC tissues. Overall survival analysis of human tissues from the cancer genome atlas(TCGA) database showed patients with high PRMT1 expression level displaying poorly prognosis. Overexpression of PRMT1 promoted, whereas small molecular inhibitors（PT100B）targeting for PRMT1 inhibited the malignancy phenotype of HCC cells. And PRMT1 activated of the key co-transactivator YAP related with Hippo signal pathway. According to preliminary results, the present research aims to further clear the impact of PRMT1 on the clinical malignant phenotypes of HCC cells by cytological experiment in vitro and by primary liver cancer mouse models in vivo, as well as treatment effect of PT1001B on experimental HCC models; deeply study the molecular mechanism of PRMT1 involved in Hippo signal pathway in the progress of hepatocarcinogenesis by protein immunoprecipitation (IP) and chromatin immunoprecipitation (ChIP) assay. This study will provide novel theoretical basis for targeted treatment of HCC.

肝癌是我国高发肿瘤，目前尚缺乏有效靶向治疗药物。PRMT1（蛋白质精氨酸甲基转移酶1）与多种恶性肿瘤的增殖转移密切相关，但其对肝癌的影响及作用机制尚不明确。我们前期研究发现PRMT1在肝癌组织中表达升高，TCGA数据库分析显示高表达PRMT1的肝癌患者预后不良，初步的细胞学实验表明PRMT1可促进肝癌细胞株的恶性表型，其靶向小分子抑制剂PT1001B对肝癌细胞的恶性表型具有良好的抑制作用；信号通路分析发现PRMT1在肝癌细胞中促进Hippo信号通路重要转录共激活因子YAP的活化。本研究将在此研究基础上利用多种体外及体内模型分析PRMT1对肝癌增殖、转移、成瘤性等恶性表型的影响，明确PT1001B靶向PRMT1治疗肝癌的作用，利用蛋白免疫共沉淀和染色质免疫共沉淀实验阐明PRMT1调控Hippo信号通路影响肝癌的分子机制，为肝癌的靶向治疗提供可靠的理论基础。

肝癌是我国高发肿瘤，目前尚缺乏有效靶向治疗药物。PRMT1（蛋白质精氨酸转移酶1）与多种恶性肿瘤的增殖转移密切相关，但其对肝癌的影响及作用机制尚不明确。我们研究发现 PRMT1在肝癌组织中表达升高，高表达PRMT1提示肝癌患者预后不良。细胞学实验表明PRMT1可促进肝癌细胞株的恶性表型，其靶向小分子抑制剂PT1001B对肝癌细胞的恶性表型具有良好的抑制作用。信号通路分析发现PRMT1在肝癌细胞中促进Hippo-YAP信号通路报告基因的活化，并通过免疫共沉淀及质谱分析发现PRMT1可直接结合YAP蛋白并甲基化修饰YAP蛋白的第124位精氨酸(R)位点，诱导YAP蛋白定位于细胞核内，促进其转录活性，该位点突变（R124K）可抑制肝癌细胞的成瘤性，抑制肝癌诱导模型的肿瘤发生。以上结果表明PRMT1通过介导YAP蛋白甲基化修饰YAPR124me2a进而促进肝癌。YAP蛋白的入核机制尚无明确报道，本课题在此基础上进一步探索了YAP蛋白的入核机制，发现甲基化修饰型YAP蛋白依赖与转录因子SOX9结合进入核内，SOX9蛋白与以分子伴侣的形式参与YAP蛋白的入核。我们的研究明确了PRMT1介导的YAPR124me2a促进肝癌的分子机制，为肝癌的靶向治疗进一步提供可靠的理论基础。