基于调控转录因子FOXA2的长链非编码RNA在肝癌转移复发中的作用及分子机制研究

Hepatocellular carcinoma (HCC), the most common primary malignant liver cancer is a global public health problem that accounts for approximately 500,000 deaths annually. Although advances in HCC diagnosis and treatment have increased the possibility of cure, HCC remains largely incurable because of poor prognosis and recurrence. Therefore, the development of innovative, targeted therapies is imperative and of high clinical significance to HCC patients. Long noncoding RNAs (lncRNAs), extensively transcribed from the mammalian genome, have gained widespread attention in recent years. They serve as important and powerful regulators of various biological activities and play critical roles in a variety of disease progression. More and more emerging evidences have demonstrated that some lncRNAs play important regulatory roles in tumorigenesis. In our preliminary study, a novel lncRNA named lncRNA-NEF was identified by RNA-sequencing. And we also found that it was significantly downregulated in HCC cells and acted as a novel activator of its neighbor gene FOXA2 in the cis-regulating manner. The further investigation showed the role of lncRNA-NEF in modulating the epithelial to mesenchymal transition (EMT) and cancer metastasis in HCC. In this proposal, we will further characterize the function of lncRNA-NEF in EMT and metastasis of HCC in vivo and in vivo studies. In addition, we will attempt to elucidate the underlying mechanism and clinical significance. The information obtained from this project will provide new insights into the pathogenesis of HCC and explore a better molecular target for HCC diagnosis and therapy.

LncRNAs是一类长度超过200个核苷酸的长链非编码RNA，作为一种转录调节因子其与肿瘤的发生发展密切相关。侵袭和转移是造成肝癌预后不良的重要因素；而且上皮间质转化(EMT)在肿瘤的侵袭转移过程中扮演重要的角色。作为EMT抑制子，转录因子FOXA2在抑制肝癌的转移复发中发挥着重要作用。越来越多研究表明，lncRNAs能顺式调控(cis-regulate)其邻近基因的表达从而发挥生物学功能。课题组利用RNA-Sequencing深度测序并结合生物信息学筛选得到一个位于FOXA2附近，并能顺式调控其表达的lncRNA，命名为lncRNA-NEF。随后的细胞实验证实该lncRNA调控肝癌细胞EMT转化及迁移。因此，本课题拟从细胞、分子、动物、组织水平上进一步阐明lncRNA-NEF在肝癌转移中的生物学功能并深入探讨其调控分子机制，为其在临床上成为肝癌治疗的新靶标提供充分的依据。

肝癌(HCC)是临床上最常见的恶性肿瘤之一，居于恶性肿瘤的第5位；占肿瘤致死原因的第3位。中国是肝癌发病重灾区，发病人数约占全球病人的55%。并且，我国肝癌患者被诊断时多已处于进展期或晚期，治疗手段非常有限，预后差；同时伴随着血行转移和癌栓形成，直接导致肝癌术后五年生存率远远低于欧美发达国家。肿瘤转移是一个非常复杂的生物学过程。其中，上皮细胞间质化.（Epithelial-mesenchymal transition, EMT）是指上皮细胞通过特定的程序转化为具有间质表型细胞的生物学过程，在肿瘤侵袭和转移中发挥着关键性作用。解决肝癌的转移复发问题是提高患者生存率的关键。故深入探讨肝癌转移的相关因素，发现新的、更为特异诊断复发转移的靶标，以及针对肝癌的复发转移给予精确的预防和治疗来提高远期疗效，成为目前临床上迫切需要解决的科学问题。.FOXA2作为肿瘤细胞EMT的抑制因子，调控包括肺癌、乳腺癌以及肝癌等多种肿瘤的转移和形成。近年来，长链非编码RNA(long noncoding RNA, lncRNAs) 被报道作为新的调控因子参与多种生命活动及疾病的发生，包括肿瘤的转移复发。而且，最近的研究报道称lncRNAs可通过顺式调控方式(cis-regulating manner)影响其邻近基因的表达从而发挥生物学功能。课题组由此推测可能存在lncRNAs调控FOXA2的表达从而影响肝癌的转移复发。.在本项目研究中，课题组以肝癌为研究模型，通过RNA-Sequencing 深度测序技术并结合生物信息学寻找能调控FOXA2 表达的lncRNA-NEF，鉴定其分子特征，进一步研究发现其抑制肝癌EMT过程和肝癌转移复发，机制研究中发现lncRNA-NEF可以结合β-catenin蛋白促进其磷酸化抑制β-catenin活性，进一步抑制肝癌经典Wnt/β-catenin信号通路；同时β-catenin作为FOXA2的抑制子，lncRNA-NEF对其的抑制会顺式激活FOXA2的活性，通过两个途径抑制肝癌的转移复发。同时利用异位、原位肿瘤肺转移模型验证其体内功能；并用人体组织样本阐明其临床意义，为肝癌的临床治疗提供一个新的分子靶标。