miR-192-5p在肝细胞癌中转录沉默，促进肿瘤干细胞干性的获得和维持

Cancer stem cells (CSCs) were thought to be responsible to tumor formation, tumor recurrence and metastasis. In this vein, targeting CSCs holds the hope of efficiently eliminating cancer. In hepatocellular carcinoma (HCC), five biomarkers have been successfully identified to isolate hepatic CSCs (HpCSCs) from human primary HCC tumor tissues. However, little is known about the implication of CSC heterogeneity and presence of shared molecular networks by 5 different groups of HpCSC+ HCCs. Here we aimed to discover the miRNA signaling pathway shared by 5 groups of HpCSC+ HCCs, which might act as the molecular targets for efficiently targeting multiple types of HpCSCs. In our preliminary data, by analyzing a total of 612 HCC specimens, we revealed a group of miRNAs to be commonly altered among five different subtypes of HpCSC+ HCCs and miR-192-5p as the top ranked miRNA with a dramatic low level in five groups of HpCSC+ HCCs. Further, suppressing miR-192-5p can significantly induce CSC activities. Interestingly, the silencing of miR-192-5p might be due to the hyper-methylation of mir-192 promoter in HCC. In this vein, we propose to study that miR-192-5p silencing at the transcriptional level in HCC promotes the initiation and maintenance of HpCSC stemness. In this project, we plan to 1) verify the silencing of miR-192-5p in multiple types of HpCSCs at the expression level and reveal the molecular mechanisms of its silencing; 2) investigate the roles and biological mechanisms of miR-192-5p in suppressing CSC abilities of HpCSCs; 3) explore possible roles for the up-stream and down-stream of miR-192-5p signaling axis as molecular biomarkers for predicting HCC subtypes with different prognosis. This project will reveal a regulatory miRNA signaling pathway being shared by different HpCSC+ HCCs, which might be driver that steers liver cells toward hepatic CSC cells, leading to hepatic carcinogenesis. These will not only improve the current understanding of the CSC heterogeneity and informed potential early diagnosis for HCC, but also pave the way to efficiently eliminate multiple types of hepatic CSCs.

肿瘤干细胞为肿瘤形成和复发的元凶，在肝细胞癌临床组织中已发现5种肿瘤干细胞标志物可成功分选肝癌干细胞。系统比较这5组标志物阳性肝癌组学谱，揭示其共享分子机制，于高效靶向性消灭多类肝癌干细胞造福患者意义重大，然而目前该项研究尚为空白。初步实验发现，在612例肝癌患者中比较这5组标志物阳性肝癌组织微小RNA表达谱，miR-192-5p在5组标志物阳性肝癌中表达显著沉默；抑制miR-192-5p可显著增强肝癌细胞干性；其表达降低与启动子区高甲基化相关。这些提示miR-192-5p可能在肝癌中转录沉默，促进肿瘤干细胞干性的获得和/或维持。本课题拟进一步验证miR-192-5p在肝癌干细胞中的表达沉默并揭示其沉默机制；检测其抑制肝癌干细胞干性的作用及原理；探索其上下游信号轴在肝癌中临床诊断和预后的分子标志物作用。本研究将深化对肝癌干细胞干性获得和维持的理解，为高效靶向性消灭肝癌干细胞提供理论依据。

肝细胞癌严重威胁我国及世界人民的生命安全，其发病率高，死亡率高。肿瘤干细胞为肿瘤形成和复发的元凶，高效靶向肿瘤干细胞对肝细胞癌患者意义重大，是减少患者死亡、延长患者生命的可能方法之一。在肝细胞癌临床组织中已发现5种肿瘤干细胞标志物可成功分选肝癌干细胞，在已知的理论体系中，这5类肝癌干细胞的信号调节通路存在较大差异，在我们设立该项目前，无5类肝癌干细胞相关信号通路的的直接比较。因此我们设立这一项目，旨在系统比较5组标志物阳性肝癌组学谱，揭示其共享分子机制，为高效靶向性消灭多类肝癌干细胞奠定坚实的基础。通过该项目，我们发现：1）5组标志物阳性肝癌组织中存在一组共同表达下调的miRNA集，其中miR-192-5p在5组标志物阳性肝癌中表达显著沉默；2）揭示miR-192-5p在肝癌尤其是肿瘤干细胞阳性肝癌患者中表达沉默的机制；3）发现miR-192-5p抑制肝癌肿瘤干细胞干性的维持；4）在肝癌细胞内，揭示miR-192-5p通过抑制PABPC4的表达来抑制肿瘤细胞干性和恶性表型；5）揭示miR-192-5p表达沉默后增强了肝癌细胞的糖酵解，通过乳酸改变与微环境细胞互作，进一步调节肿瘤干性。同时，我们还发现其他几个与肝癌干细胞相关的基因如miR-125b，CYP39A1等，通过该项目延伸了我们对肿瘤干细胞及肝癌发生发展机制的研究。该项目的研究成果不仅填补了我们对多类肿瘤干细胞共性调节通路理解的空白，亦深化了我们对肝癌干细胞干性获得和维持的理解，为高效靶向性消灭肝癌干细胞奠定了坚实的理论基础。