SETD2介导的组蛋白H3K36三甲基化调控FGFBP1促进肝细胞癌进展的机制研究

Histone methylation has an important role in the development of hepatocellular carcinoma. SETD2 is the only known methyltransferase of histone H3K36 trimethylation, but there is almost no report about its function in hepatocellular carcinoma. Our previous results showed that the expression of SETD2 in hepatocellular carcinoma was up-regulated, and its knockdown could inhibit the proliferation of hepatocellular carcinoma cell；The expression of FGFBP1 in SETD2-knockdown hepatocellular carcinoma cell was decrease-regulated measured by transcriptome sequencing, so we supposed that SETD2, as an oncogene, promoted the expression of FGFBP1 through altering H3K36me3 level of FGFBP1 and then promoted hepatocellular carcinoma development. In this project, we will first investigate the function of SETD2 in hepatocellular carcinoma by cell experiment, knockout mice experiment and clinical case, then we will study that whether SETD2 regulate the expression of FGFBP1 through altering the H3K36me3 level of FGFBP1 according to ChIP and so on, finally we will verify that whether SETD2 promote hepatocellular carcinoma development through regulating FGFBP1. This project will study the pathogenesis of hepatocellular carcinoma from the angle of histone methylation and offer theoretical basis for new therapeutic targets of hepatocellular carcinoma.

组蛋白甲基化在肝细胞癌进展中发挥重要作用。SETD2是目前已知的唯一催化组蛋白H3第36位赖氨酸三甲基化（H3K36me3）的甲基转移酶，其在肝细胞癌中的作用尚不清楚。我们前期发现肝细胞癌中SETD2表达升高，沉默SETD2可抑制肝细胞癌细胞增殖；转录组测序发现沉默SETD2后FGFBP1表达显著下调，由此我们推测SETD2作为癌基因，通过改变FGFBP1转录区域的H3K36me3水平，促进FGFBP1转录，进而促进肝细胞癌进展。本项目拟首先在细胞、基因敲除鼠和临床病例中明确SETD2在肝细胞癌进展中的作用；其次利用染色质免疫共沉淀等技术阐明SETD2是否通过改变FGFBP1转录区域的H3K36me3水平促进FGFBP1转录；最后通过挽救实验验证SETD2是否通过调控FGFBP1促进肝细胞癌进展。本项目从组蛋白甲基化角度研究肝细胞癌致病机制，这为探索肝细胞癌诊断治疗新靶点提供研究依据。

肝细胞癌，作为原发性肝癌的主要类型，是一种发病率和死亡率均很高的全球范围最常见的恶性肿瘤，但其发病机制尚不完全清楚。组蛋白翻译后修饰尤其是组蛋白甲基化修饰在肝细胞癌的进展中具有重要作用，这为研究肝细胞癌致病机制和诊断治疗新靶点提供新思路。作为目前已知的唯一催化组蛋白H3K36三甲基化的甲基转移酶，SETD2参与多种肿瘤如非小细胞肺癌、肾细胞癌等的发生和发展，但是其在肝细胞癌中的作用尚不明确。本项目主要通过生物信息学分析和细胞实验研究SETD2在肝细胞癌中的作用及其机制。TCGA数据和临床肝细胞癌患者肿瘤标本的RT-PCR数据表明肝细胞癌中SETD2是过表达的，且其高表达与肝细胞癌患者差的预后密切相关；体外功能缺失实验表明沉默SETD2能抑制肝细胞癌细胞的增殖和迁移，过表达SETD2能促进肝细胞癌细胞的增殖和迁移；通过转录组测序在沉默SETD2的肝细胞癌细胞BEL-7402中共鉴定出81个显著性上调的差异基因和42个显著性下调的差异基因，我们在下调的差异基因中筛选出SETD2的潜在下游靶基因CCDC82进行后续研究。TCGA数据表明肝细胞癌患者肿瘤组织中CCDC82是过表达的，且其表达情况是与SETD2成正相关的，CCDC82的高表达与肝细胞癌患者差的预后密切相关。本项目的研究结果表明SETD2及其潜在下游靶基因CCDC82作为癌基因在肝细胞癌中发挥重要作用，SETD2和CCDC82可能作为肝细胞癌的预后指标和诊断治疗新靶点发挥重要作用。