MiR-612对肝癌干细胞形成及肝癌转移的调节作用

Tumor metastasis is a pivotal factor on HCC prognosis. In the process of invasive-metastatic cascade, epithelial and mesnchymal transition (EMT) has been thought to be an important driver of cell translocation of HCC, while cancer stem cell (CSC) has been thought to be a determined factor of HCC colonization and outgrowth in a distant organ. In our previous study, we confirmed that miR-612 was able to negatively regulate the EMT, local invasion and dissemination of HCC. In this project, we want to continuously explore the effects of miR-612 on expressions, subcellular localizations, recyclings and transcriptional activities of Numb, E-cadherin and beta-catenin using HCCLM3, HepG2 cells, as well as HCC surgical tissues from clinic. Furthermore, we want to elucidate the regulatory roles of miR-612 in the formation of CSC and tumor metastasis of HCC via Notch and Wnt/beta-catenin signaling pathways, for establishing a theoretical basis of HCC prognosis and therapeutics based on miR-612.

肝癌（HCC）转移是影响肝癌预后的关键。在肝癌侵袭转移链中(Invasive-metastatic cascade of HCC), EMT (epithelial and mesenchymal transition) 是肝癌转移的重要驱动力，而CSC (Cancer stem cell) 是肝癌转移的决定性因素。在前期工作中，我们证实miR-612在肝癌EMT、侵袭和播撒中起着关键性的作用。本项目拟以HCCLM3、HepG2细胞以及临床肝癌标本为研究对象，进一步观察miR-612对Numb、E-cadherin和beta-catenin分子的表达、亚细胞定位、代谢以及转录功能的变化，来探讨miR-612对Notch及Wnt/beta-catenin通路信号传导的影响及其在肝癌CSC形成和肝癌转移中的作用,为基于miR-612的HCC转移分子预测及治疗奠定理论基础。

原发性肝细胞癌（HCC）是我国常见的恶性肿瘤之一，复发转移制约患者长期生存。转移的发生需要肿瘤细胞从原发器官播散至次级靶器官，并且能在次级靶器官中的克隆形成和生长。MicroRNAs（miRNAs）是人体细胞功能基因和蛋白表达重要的调控分子。前期研究工作中，我们从临床和实验两个层面较完整地证实了miR-612表达及功能缺失诱导肝癌细胞EMT。在此基础上，我们发现miR-612具有抑制肝癌细胞干性特征。第一，miR-612可以抑制肝癌细胞肿瘤球的形成和非黏附性克隆生长，可抑制肝癌细胞移植瘤的形成和生长。第二，miR-612对HCCLM3和HepG2细胞的化疗敏感性具有负性调节作用。第三，miR-612可靶向作用Sp1，负向调节干细胞转录因子Nanog，从而影响肝癌干细胞分子CD133和EpCAM的表达。另外，我们还发现，miR-612表达水平可影响裸鼠移植瘤中的肝癌细胞分布和肿瘤侵袭带的形成，表明其在肝癌转移过程中发挥重要作用。通过对E-cadherin和β-catenin分子亚细胞定位的观察，结合进一步的研究发现，miR-612可负性调节Wnt通路靶基因的表达，从而调控Wnt通路的信号传导。这一发现对miR-612的HCC转移分子预测及治疗奠定理论基础。