LINC00589对肝癌细胞生长与转移的调控及其分子机制研究

Long non-coding RNA ( LncRNA）is a class of >200 nucleotides, non-coding RNA molecules which is encoded and transcribed by the genome. LncRNA can regulate gene expression and play an essential role in the physiological process at the epigenetic, transcriptional and post-transcriptional levels. Abnormality of lncRNAs usually contributes to the development of human disease such as cancer. Some lncRNAs related to hepatocellular carcinoma (HCC) have been identified, however, the functional role and molecular mechanism of lncRNAs in HCC remains largely unknown. Our preliminary study shows that LINC00589 associated with genomic copy number variation is significantly decreased in HCC, and inhibits HCC cell growth and migration. In the proposal, we will further analyze the biological characteristics of LINC00589; investigate its role in regulating HCC cell growth and metastasis; determine its interacting proteins, direct downstream effector genes and related signaling pathways to reveal the underlying mechanisms by which LINC00589 regulates HCC cell growth and metastasis; analyze the clinical implications of the above-mentioned LINC00589/interacting protein/related signaling pathways. This study will provide us new knowledge about lncRNAs and their complex interplays with other macromolecules such as proteins in the cell. Meanwhile, the study will identify LINC00589 as a novel tumor suppressor candidate in HCC, and benefit for our better understanding of the underlying molecular mechanism for HCC cell growth and metastasis.

长非编码RNA（LncRNA）是指一类由基因组转录，长度大于200个核苷酸，不编码蛋白质的RNA分子。LncRNA通常在表观遗传学、转录水平及转录后水平对基因表达进行调控。LncRNA的异常可导致恶性肿瘤的发生。已发现一些与肝癌发生与转移密切相关的 lncRNA，但lncRNA在肝癌发病中的作用及分子机制仍有待深入阐明。前期我们通过肝癌染色体变异区相关lncRNA筛选发现LINC00589在肝癌中下调、抑制肝癌细胞生长与迁移。本项目将深入研究LINC00589对肝癌细胞生长与转移的调控作用，明确其生物学功能；鉴定LINC00589相互作用蛋白及相关信号通路，阐明其调控肝癌细胞生长与转移的分子机制；明确这些相互作用及调控通路与肝癌复发转移与预后等相关性及临床意义。本项目将揭示LINC00589可作为一类新的肝癌抑癌基因，为深入理解肝癌发病分子机理提供实验依据。

前期通过SNP 6.0 芯片发现在肝癌基因组中有1,241个显著差异的拷贝数变异位点。LINC00589位于8p12.1，在HCC中高频缺失，且表达下调。我们将LINC00589命名为TSLNC8（Tumor suppressor lncRNA on chromosome 8p12）。TSLNC8表达和患者肿瘤的数目、癌栓的有无和病理分期呈负相关，且其高表达的HCC患者比低表达的HCC患者预后好； TSLNC8发挥抑癌基因功能。通过RNA-pulldown结合质谱分析，发现STAT3可与TSLNC8结合。TSLNC8能够抑制STAT3的转录活性及JAK-STAT下游mRNA表达。TSLNC8能够抑制STAT3-Y705位点的磷酸化，促进STAT3-S727位点的磷酸化，来实现调控HCC细胞的生长与迁移。同时发现TKT作为TSLNC8另一特异性结合蛋白，与STAT3竞争性结合TSLNC8，以“TSLNC8-STAT3/TKT”模式调控STAT3磷酸化状态和活性；TSLNC8抑癌功能主要是通过抑制IL-6/STAT3信号通路来实现； TKT高表达同时STAT3-Y705高磷酸化、TKT高表达同时STAT3-S727低磷酸化、以及STAT3-Y705高磷酸化同时STAT3-S727低磷酸化，与肝癌患者恶性临床特征的正相关，相应的患者预后较差。TSLNC8-TKT-STAT3 axis作为HCC的潜在治疗靶点。另外，发现定位于1q21.2染色体扩增区域的 LINC01138是一个新的肝癌候选癌基因，主要通过与癌蛋白PRMT5相互作用，调控其蛋白稳定性发挥促癌作用。肝癌染色体扩增区域1q21.1上antisense LINC00624破坏HDAC6-TIRM28-ZNF354C转录阻遏复合体的形成，解除该复合体在靶基因启动子区的结合，消除转录抑制作用，从而激活下游靶基因的转录，促进肝癌的进展。炎症LINC00665/PKR/NF-κB正反馈环在肝癌发生发展中起着重要的作用，是肝癌治疗一个重要的潜在靶点。该项目已在Hepatology, Nature Communications, Briefings in Bioinformatics等期刊发表该基金标注论文6篇；培养博士研究生3名，硕士研究生2名。高质量完成该项目既定研究计划。