转录因子Hes1靶向EZH2调控鼻咽癌分化的研究

More than 95% of nasopharyngeal carcinoma (NPCs) are pathologically diagnosed as Type III undifferentiated carcinomas, which provides a unique model for investigating the differentiation therapy of solid tumors. Our preliminary studies reveal that (1) Hes1 may play a role of anti-differentiation in NPC, (2) EZH2 is a target gene of Hes1 and Hes1 positively regulates the EZH2 expression. Recent study showed that silencing EZH2 expression by RNA interference promotes the differentiation of NPC cells. These aforementioned findings suggest that Hes1 regulates NPC cell differentiation by its target gene EZH2. Based on this, the project will further define the roles of Hes1 in NPC differentiation, and then confirm that the function of Hes1 in NPC differentiation can be mediated by its target gene EZH2. Secondly, the cells expressing shHes1 or shSCR are collected, followed by RNA sequencing to screen the differentially expressed genes, and predicting the mechanism involving in Hes1-mediated NPC differentiation. Finally, this project plans to explore the in vivo inhibitory effects of siRNA-Hes1 alone or in combination with radiotherapy on NPC cells, and the clinical specimens verifies the relationship between Hes1 & EZH2 and differentiation-related genes, stemness genes and radiation resistance genes. Finally, the expected results will provide theoretical basis and potential therapeutic targets for the differentiation therapy of NPC.

绝大多数鼻咽癌属于未分化癌，为研究实体肿瘤的诱导分化治疗提供了一个独特的模型。我们前期研究发现，Hes1在鼻咽癌分化过程中可能起抗分化的作用，EZH2是Hes1的靶基因，Hes1正向调控EZH2的表达，而新近研究证实沉默EZH2表达可促进鼻咽癌细胞分化，这些提示Hes1有可能通过EZH2调控鼻咽癌细胞的分化。基此，本项目拟进一步系统阐明Hes1在鼻咽癌分化过程中的作用，并确证Hes1调控鼻咽癌细胞分化的作用可否由EZH2介导。其次收集表达shHes1和对照的鼻咽癌细胞，采用RNA测序筛选差异表达基因，并利用生物信息学软件预测Hes1影响鼻咽癌细胞分化的可能机制与调控网络，进而功能验证。最后探讨siRNA-Hes1单药或联合放疗的体内抑瘤效果；临床标本验证Hes1和EZH2与分化基因、干性基因和辐射抗性基因等表达相关性及临床病理意义。预期成果将为鼻咽癌诱导分化治疗提供理论依据及潜在治疗靶标。

绝大多数鼻咽癌属于未分化癌，为研究实体肿瘤的诱导分化治疗提供了一个独特模型。本研究发现，Hes-1在鼻咽癌组织中表达显著上调及其表达与TNM和临床分期及生存预后存在关联，提示Hes-1可能与鼻咽癌发病密切相关。Hes-1正向调控鼻咽癌细胞增殖和干性。Hes-1在未分化型鼻咽癌组织中高表达，不同分化类型的鼻咽癌组织中Hes-1表达趋势与CK8和Involucrin相反，与CK13的一致，全反式维甲酸(ATRA)诱导鼻咽癌细胞分化过程中，Hes-1表达呈下降趋势，这些提示Hes-1可能发挥抗分化作用；Hes-1沉默的鼻咽癌细胞中CK8和Involucrin表达升高，而CK13表达则降低，表明Hes-1沉默促进鼻咽癌细胞分化。EZH2是Hes-1的靶基因；鼻咽癌组织中Hes-1表达与EZH2表达呈正相关，与EZH2的靶基因IKKα表达则呈负相关；ATRA诱导细胞分化过程中，Hes-1及EZH2表达呈下降趋势，IKKα表达则呈上升趋势，提示Hes-1和EZH2在鼻咽癌细胞分化中发挥抗分化作用，IKKα发挥促分化作用。microRNA-9对鼻咽癌细胞增殖和干性的调控作用可由其靶基因Hes-1介导。microRNA-9高效模拟物 agomir具有强的体内抗肿瘤效果。内质网应激(ER stress)可诱导鼻咽癌细胞分化。ER stress诱导鼻咽癌细胞分化的作用可能由Hes-1-EZH2-IKKa轴介导。总之，本研究揭示了Hes-1靶向EZH2调控鼻咽癌分化的机制，即microRNA-9靶向下调Hes-1表达或鼻咽癌细胞上诱导内质网应激后引起Hes-1和EZH2表达下调，然后引起EZH2的靶基因IKK表达上调，进而促进鼻咽癌细胞分化；microRNA-9高效模拟物或推测内质网应激诱导剂可能具有很强的体内抗肿瘤作用，其在鼻咽癌临床治疗中具有潜在应用价值。课题执行期间，在Cell Death & Disease、Cell Death Discovery、Laboratory Investigation和Journal of Translational Medicine等上发表10篇SCI论文，最高影响因子为6.304，另有2篇SCI论文在投。在课题执行期间获得2项国家自然科学基金面上项目资助。在人才培养方面，共培养博士4人和硕士4人，招收博士后1人，有1人获得副研究员专业技术职务。