EB病毒微小RNA调控EB病毒相关胃癌干细胞自我更新及致瘤的机制及意义

Cancer stem cell is known as cancer initiating cell. Whether or not Epstein-Barr virus (EBV) regulates the self-renewal and tumorigenicity of the Epstein-Barr virus-associated gastric carcinoma (EBVaGC) stem cell? It is beneficial to answer the question correctly for bringing to light whether EBV is a tumorigenic factor of EBVaGC and searching for effective treatment. Our preliminary study found that the cell subpopulation with self-renewal and tumorigenicity in EBVaGC cells were CD44+CD24- cells; the expression of ebv-miR-BART10-3p/19-3p was increased in CD44+CD24- cells; the target sequences of ebv-miR-BART10-3p/19-3p were in the mRNA 3’-UTRs (untranslated regions) of APC and NLK, which are the Wnt signaling pathway inhibitors; and the two ebv-miRNAs could down-regulate the activity of luciferase report gene of APC and NLK. This is a new discovery in the research field of EBVaGC. Since Wnt signaling pathway is important to promote the stemness (self-renewal and tumorigenicity) of cancer stem cells, if APC and NLK, the inhibitors of Wnt signaling pathway, could be down-regulated by the two ebv-miRNAs, the Wnt signaling pathway may be activated in the EBVaGC stem cells. So, the two ebv-miRNAs can promote the self-renewal and tumorigenicity of the EBVaGC stem cells by activating Wnt signaling pathway. This project intends to investigate the influences of the two ebv-miRNAs on APC and NLK expression, Wnt signaling pathway, epithelial-mesenchymal transition and cancer stem cell markers, to observe the impact of the two ebv-miRNAs on cancer stem cell proliferation, apoptosis, drug resistance, self-renewal and tumorigenicity, and to explore the correlation between the ebv-miRNAs expression and the clinicopathological features and prognosis of the EBVaGC patients. The aims of this project are to reveal the molecular mechanisms of EBV regulation of EBVaGC stem cells, and to provide a scientific basis for developing new treatment of EBVaGC.

肿瘤干细胞是肿瘤始动细胞，EBV是否调控EBVaGC干细胞自我更新和成瘤等干性？这对揭示EBV是否为EBVaGC致癌因子及寻找有效治疗措施具有重要意义。我们前期研究发现：EBVaGC中CD44+CD24-细胞具有肿瘤干细胞特性；EBV-miR-BART10-3p/19-3p在CD44+CD24-细胞中高表达，能下调Wnt信号转导抑制因子APC和NLK荧光素酶报告基因活性。Wnt信号是促进肿瘤干细胞干性的重要通路，其抑制因子受到抑制后可能激活Wnt信号转导，促进EBVaGC干细胞的干性。课题拟在EBVaGC细胞、小鼠移植瘤和人组织标本上，观察上述2个miRs：对APC、NLK及Wnt信号通路中关键分子表达的影响；对EBVaGC干细胞自我更新和成瘤等影响；对EBVaGC临床病理特征和预后的影响。旨在揭示EBV促进EBVaGC干细胞干性的分子机制，为阐明EBV致癌机制和寻找新的治疗方法奠定基础。

肿瘤干细胞是肿瘤的始动细胞，EBV是否调控EB病毒相关胃癌（EBVaGC）干细胞“干性”？未见报道。在本基金资助及课题组成员共同努力下，我们在EBV调控EBVaGC干细胞“干性”分子机制方面展开系列研究，主要发现如下：1.ebv-miR-BART10-3p/22通过下调Wnt通路负调控因子APC和DKK1表达从而激活Wnt/β-catenin通路，促进EBVaGC侵袭转移，与EBVaGC干细胞“干性”调控相关；2.EBV可编码环状RNA，其中ebv-circLMP2A在EBVaGC干细胞中高表达，通过结合miR-3908使后者对靶基因TRIM59负调控作用减弱而导致TRIM59表达上调，从而促进EMT并维持EBVaGC干细胞“干性”。上述结果表明EBV可通过其编码产物调控EBVaGC干细胞“干性”，这是“EBV是EBVaGC致病因子”的另一个重要佐证，对寻找EBVaGC有效治疗措施也具有重要意义。此外，课题组还对EBVaGC分子表达、免疫微环境及EBV全基因组序列进行分析，发现：1.EBVaGC高表达PIK3CA、JAK2、PD-L1和PD-L2，低表达HER-2，预后较好；2.EBVaGC肿瘤微环境存在免疫激活和免疫抑制，免疫微环境失衡可能影响肿瘤进展；3.完成2例广东地区EBVaGC中EBV全基因组序列测定，这是首次对鼻咽癌高发区EBVaGC中EBV进行全基因组序列分析。上述结果共发表论文12篇，其中SCI论文11篇，总影响因子33.811，单篇最高影响因子5.49。部分研究结果在2016年第17届及2018年第18届国际EB病毒及相关疾病研究年会上受邀大会发言交流。以上述发现为基础，团队成员获得1项国家自然科学基金项目资助（81602146）。培养研究生12名，其中3名硕士和2名博士已毕业，目前在读博士6名，硕士1名。