缺氧诱导的长链非编码RNA分子lnc-MC5R-8通过Girdin/Tks5信号轴促进肝癌侵袭转移的机制研究

肝癌是我国高发、高致死率的恶性肿瘤之一，探索新的肝癌标志物和治疗靶点极其重要。申请人前期研究发现lnc-MC5R-8在肝癌组织高表达，与病程进展、预后不良显著相关；该lncRNA受低氧诱导高表达且过表达促进肝癌细胞增殖侵袭；深入研究发现：该lncRNA与miR-139-5p及miR-29c-5p存在结合位点，后两者可分别靶向抑制Girdin和Tks5表达，而Girdin调控Tks5磷酸化修饰和活化过程；已证实Girdin和Tks5是侵袭性伪足关键蛋白。因此提出科学假设：lnc-MC5R-8受低氧诱导高表达，通过内源竞争性RNA机制激活Girdin/Tks5轴，促进肝癌侵袭转移。申请人拟利用荧光素酶、RIP、Pull down等体外生化和细胞功能实验、体内动物模型和临床数据关联分析等方法，深入研究lnc-MC5R-8影响肝癌侵袭转移和恶性进展的机理，为未来发展靶向治疗等临床转化提供新靶点。

Hepatocellular carcinoma (HCC) is a highly prevalent and fatal cancer in China. It is extremely important to uncover the biomarkers and therapeutic targets for HCC. Our preliminary studies indicated that up-regulated lnc-MC5R-8 expression existed in HCC tissues and was significantly associated with higher tumor stage and worse survival of HCC patients. The lnc-MC5R-8 expression was induced by hypoxia and lnc-MC5R-8 over-expression promoted the proliferation, migration, and invasion of HCC cells. Further bioinformatics analysis and in vitro studies revealed that lnc-MC5R-8 had the sites for the binding of miR-139-5p and miR-29c-5p, which targeted and inhibited the Girdin and Tks5 expression, respectively. Furthermore, up-regulated lnc-MC5R-8 enhanced Girdin expression, which increased Tks5 phosphorylation and activation. Additionally, our data demonstrated that up-regulated Girdin and Tks5 expression and activation promoted the invasion and metastasis of HCC. Accordingly, we hypothesize that lnc-MC5R-8 induced by hypoxia may act as a competitive endogenous RNA to activate the Girdin and Tks5 axis, promoting the invasion and metastasis of HCC. With combination of gain and loss of function (gene over-expression and knockdown), luciferase reporter, RIP, RNA pull down and other molecular biological assays, animal models as well as clinical specimen analysis, we will determine how altered lnc-MC5R-8 expression regulates the invasion and metastasis of HCC; explore the molecular mechanisms by which lnc-MC5R-8 targets the miR-139-5p and miR-29c-5p to activate the Girdin/Tks5 axis; and examine the relationship between the expression levels of individual key molecules in human HCC tissues and the metastasis of HCC. Our findings will provide new insights into the molecular mechanisms underlying HCC metastasis, and uncover new therapeutic targets for the development of target therapies and their potential clinical translation.