LncRNA-HOTTIP招募PRC2/诱捕eIF4A3/吸附miR615促进胆管癌发生发展的研究

There is increasing evidence that the dysregulation of long non-coding RNA (LncRNA) is closely associated with the occurrence and progression of many cancers. In the preliminary studies, we have demonstrated that the highregulated LncRNA-HOTTIP promoted the tumorigenesis through downregulating FoxA1 expression in cholangiocarcinoma and LncRNA-HOTTIP could both recruit PRC2 and decoy eIF4A3 to exert dual functions in transcriptional and translational regulation of FoxA1 expression. Meanwhile, LncRNA-HOTTIP could function as endogenous sponge for miR-615 to upregulate CEBPA expression which could further bind to the promoter of LncRNA-HOTTIP to enhance its transcription. Therefore, we hypothesize that the underlying mechanism of carcinogenesis and sustaining dysregulation of LncRNA-HOTTIP depends on regulating its downstream genes expression at transcriptional and translational levels by recruiting PRC2/decoying eIF4A3/sponging miR-615 in cholangiocarcinoma. A variety of approaches including multiple cell lines, animal models and tissue samples will be applied to validate this hypothesis. The implementation of this project will innovatively provide the first evidence for establishing the molecular regulatory network of dysregulated LncRNA in cholangiocarcinoma and illuminating the underlying mechanisms. The clinical application value of this project is that the obtained data will provide the theoretical basis and potential targets for the prevention and treatment of cholangiocarcinoma.

研究表明长链非编码RNA（LncRNA）的异常表达与肿瘤的发生发展密切相关。前期工作中我们发现：胆管癌中高表达的LncRNA-HOTTIP通过招募PRC2和诱捕eIF4A3来抑制FoxA1 mRNA与蛋白合成从而促进肿瘤的恶性生物学行为；同时LncRNA-HOTTIP作为内源性海绵通过对miR-615/CEBPA的调控来促进其自身的基因转录。因此，我们提出科学假设：胆管癌中失调控的LncRNA-HOTTIP以多重机制（招募PRC2/诱捕eIF4A3/吸附miR-615）于转录和翻译两个水平通过对下游基因表达的调控来实现其对肿瘤发生发展的促癌作用并维持自身的持续性高表达。我们将利用不同细胞、动物模型并结合组织样本通过多种实验方法来验证上述科学假设并阐明其机制。本课题的实施将建立肿瘤中失调控LncRNA的细胞内分子调控网络并揭示其作用机制；为预防和治疗胆管癌提供新的理论依据与干预靶点。

胆管癌是起源于胆管上皮细胞的消化系统恶性肿瘤；现有研究表明长链非编码RNA（LncRNA）的异常表达与胆管癌的发生发展密切相关。本项目主要探究胆管癌中LncRNA表达情况、LncRNA-HOTTIP促癌作用及机制以及其维持自身持续高表达的调控机制。借助体外细胞实验、动物模型构建并结合组织样本定量检测与分析证实：胆管癌中存在LncRNA表达谱的改变并且异常高表达的LncRNA-HOTTIP能够促进肿瘤增殖与侵袭转移并推进细胞周期；LncRNA-HOTTIP通过负向调控下游基因FoxA1的表达来促进肿瘤的恶性生物学行为；通过招募PRC2至FoxA1启动子区对组蛋白（H3K27）进行甲基化修饰在转录水平抑制FoxA1的mRNA合成；借助诱捕机制与eIF4A3结合，阻断eIF4A3与mRNA 5’-UTR的结合，进而抑制FoxA1的蛋白合成；同时LncRNA-HOTTIP通过海绵吸附miR-615来上调转录因子CEBPA的表达，高表达的CEPBA能够进一步与LncRNA-HOTTIP启动子结合促进基因转录进而维持其异常高表达。本项目以胆管癌中LncRNA的异常表达为切入点，首次证实胆管癌中存在LncRNA表达谱的改变并率先洞悉失调控LncRNA-HOTTIP以多重机制（招募/诱捕/吸附）于转录和翻译两个水平通过对下游基因表达的调控来实现其促癌作用并维持自身持续高表达。本课题的实施将丰富和拓展肿瘤细胞内ncRNA调控网络的认知与理解，为胆管癌治疗提供新的理论依据与干预靶点，为后续的进一步深入研究奠定基础，其意义将不仅限于肿瘤领域的科学研究。