RNA结合蛋白NONO在肝癌发生发展中的功能及其分子机制研究

In eukaryotes, RNA-binding proteins (RBPs) exhibit important roles on their target RNAs in general gene expression and post transcriptional gene regulation, with many processes involved, such as RNA transcription, RNA editing, RNA splicing, RNA modification, RNA decay, and so on. These mechanisms allow the existence of RNAs with variable length after transcription of genome and contribute to drive proteome diversity. Disruptions of these processes have been associated with a variety of diseases, including cancer. The pattern of the expression levels and the specific isoforms of numerous genes is altered when cells go through the oncogenic process of carcinogenesis and metastasis, towards a more aggressive and invasive cancer phenotype. Emerging evidence showed that the de-regulation of RBP genes may have a role in hepatocarcinogenesis. Some RBPs can also bind with DNA, which are nominated as DNA-, RNA-binding proteins (DRBPs), and generate both long-lasting effects (through regulating transcription) and immediate effects (through regulating RNA turnover) on their target genes. The unappreci¬ated dual DNA- and RNA-binding capacity of these DRBPs allows a powerful, combinatorial control over gene expression at both the DNA and the RNA lev¬els, so it is essential to organizing our current molecular and genetic understanding of their roles. We have identified a set of master DRBPs with somatic mutations in hepatocellular carcinoma (HCC) by high-throughput exome sequencing, RNA sequencing and bioinformatics analyses. Furthermore, functional assay indicated that some of these HCC-related DRBPs, such as NONO, which has significant roles on liver cancer cells proliferation and migration. In this project, we will focus on the expression levels and clinical significance of HCC-related DRBPs as well as their biological function and molecular mechanism. This will surely contribute to a better understanding of the disease and to the development of new effective therapies.

RNA结合蛋白（RBPs）能够参与包括转录水平和转录后水平的基因表达调控，包括基因转录，RNA编辑，RNA剪切，RNA修饰，RNA降解等过程。这些过程使遗传信息在转录后被有效利用，产生多种长度的RNA分子，有效的保证蛋白质组多样性。肿瘤细胞可劫持这些过程使细胞产生更多有利于生长和转移的蛋白质。DNA、RNA结合蛋白（DRBPs）作为一类能够结合DNA的RBPs，能够将基因表达的各层面调控有机整合起来，真正兼并性地实现了对基因表达的上中游调控。本研究前期工作采用外显子测序、高通量RNA测序，结合生物信息分析，鉴定并筛选出肝癌中发生高频突变的DRBP基因群；并通过相关的功能实验，发现DRBP基因NONO的异常表达对肝癌细胞的生物学行为有显著影响。本项目将在前期工作基础上，进一步研究肝癌中高频突变的DRBP基因NONO的在肝癌发生发展过程中的生物学功能、分子作用机制及临床意义。这些将为理解肝癌的

RNA结合蛋白（RBPs）是一类能与RNA结合的蛋白，广泛地存在于RNA的转录、剪接、翻译、稳定和降解等各个生物学过程，对RNA的调控及发挥其生物学功能至关重要。最近的研究表明，RBP的异常表达和功能能够直接影响下游RNA分子的表达、剪接等过程，促进癌症恶化进展。本研究内容阐述了RNA结合蛋白NONO（p54nrb）在肝癌中的功能和调控机制。NONO在肝癌样本中发生mRNA和蛋白水平的异常高表达，高表达NONO与患者的不良预后及易复发正相关。NONO能够促进肝癌细胞的体内、体外生长以及肿瘤侵袭过程。NONO通过调控BIN-1 mRNA转录本的可变剪接发挥生物学功能。在正常肝细胞中，BIN-1 mRNA产生短的转录本BIN1-S，该转录本蛋白产物通过抑制c-Myc识别结合靶基因启动子，从而发挥抑癌功能。在肝癌细胞中，NONO高表达促进BIN1-L转录本的产生，BIN1-L蛋白产物通过抑制CUL-3依赖的泛素化-蛋白酶体途径稳定PLK1的蛋白水平，从而发挥促癌功能。这一可变剪接形式的转换依赖于 NONO与DHX9和SFPQ形成蛋白复合物的功能。在肝癌中，DHX9和SFPQ基因也发生异常高表达，并能够促进细胞的生长和转移。肝癌病人同时高表达NONO和SFPQ显示出更差的预后和更高的肿瘤复发率。这些研究结果表明RBP NONO在肝癌发生发展过程中起到重要作用，这为后续的肝癌精准治疗提供了更多的可能性。