RNA结合蛋白CPEB3在肝癌肿瘤干细胞中的作用及机制研究

The theory of cancer stem cell provides new insights for recurrent and chemo-resistance of tumors. Elucidating the mechanism of cancer stem cell is the key point which need be solved. CPEB family is a series of sequence specific RNA- binding proteins. Our research group for the first time, reported that CPEB3 is a target of miR-107 to suppress tumor progression. Based on the analysis of TCGA database, we find CPEB3 is down-regulated in human cancerous tissue compared to normal tissues, and is negatively correlates with patient’s prognosis. Furthermore, our results show that CPEB3 can inhibit tumor-sphere formation and colony formation of HCC cells significantly. Moreover, over-expressing of CPEB3 can down-regulate the “markers” of liver cancer stem cell (LCSC). Also, RIP-Seq result shows β-catenin is a potential target of CPEB3. So we speculate, CPEB3 may regulate LCSC through Wnt/β-catenin signaling. In this project, we intend to study the role of CPEB3 in LCSC generating and maintenance both in vitro and in vivo through the transformation of liver stem cell model and DEN induced carcinogenesis model in CPEB3-/- mice. Besides, we also intend to verify whether CPEB3 regulates LCSC by targeting Wnt/β-catenin signaling. This project will provide new evidences for elucidating the mechanism of LCSC.

肿瘤干细胞理论为解决肿瘤复发和耐药提供了新思路，阐明肿瘤干细胞相关机制是亟待解决的关键问题。CPEB是一类序列特异性的RNA结合蛋白。本课题组首次报道了CPEB3可以抑制肝癌细胞增殖和转移。TCGA数据库分析发现人肝癌样本中CPEB3表达明显下调并与预后呈负相关。进一步研究发现CPEB3明显抑制肝癌细胞成球和克隆形成能力；过表达CPEB3明显下调肝癌干细胞（LCSC）标志性分子。RIP-Seq结果发现β-catenin是CPEB3的潜在靶点。因此提出假设“CPEB3通过靶向Wnt/β-catenin通路调节LCSC干性特征”。本项目将在体外诱导肝干细胞恶变、体内利用CPEB3-/-小鼠建立诱癌模型，从LCSC形成和干性维持两方面深入探讨CPEB3在LCSC中的作用。验证CPEB3通过靶向Wnt/β-catenin通路抑制LCSC的机制。本项目将为揭示LCSC机制提供新的线索。

肿瘤干细胞理论为解决肿瘤转移复发提供了重要思路，CPEB3是一类序列特异性的RNA结合的蛋白，课题组前期研究表明CPEB3能调控肝癌细胞干性相关表征。在肝癌中阐明CPEB3对肝癌干细胞干性维持等肿瘤发生发展过程中重要表征的调控作用将对肝癌发生发展的机制研究具有重要意义。本项目首次利用cpeb3敲除小鼠建立了多种肝癌疾病模型，结合肝癌临床组织样本分析，证实了CPEB3在体内抑制干性相关标志性分子并降低了肝癌诱癌模型的癌症易感性。在体外水平证实了CPEB3抑制肝癌细胞成球能力、自我更新能力、上皮间质化、细胞转移能力等干性相关表征及细胞信号通路；通过生物信息学方法对细胞实验及临床样本数据进行综合分析，探究CPEB3在肝癌中的调控机制，初步证实β-catenin为CPEB3潜在靶基因。此外，本项目发现并证实CPEB3在肝癌发生过程中影响肝星形细胞活化、分泌和肝脏胶原沉积。肝星形细胞与肿瘤干细胞具有多种共同特征，包括较强的存活及自我更新能力、克隆形成能力、细胞成球能力及分化、分泌能力等，对肝脏内微环境具有强大的调控作用。课题组对CPEB3对肝癌肿瘤微环境中肝星形细胞与肝癌细胞互作的功能及机制的研究发现，CPEB3能够影响肝星形细胞与肝癌细胞的相互作用并进一步抑制肝癌细胞的转移，为肝癌转移方面的研究工作提供了新思路。