新发现的环状RNA (Circ-TNPO3)具有竞争结合miR-199a-5p与HuR蛋白的双重功能及其在抑制胃癌转移中的作用机制研究

Gastric cancer is one of the most common malignant tumors in China, however the molecular mechanism underlying the development and metastasis of gastric cancer remains unclear. circRNAs are novel non-coding RNAs with important regulatory role, growing evidence has shown that aberrant circRNAs expression correlates with various human cancers. Our previous study identified a novel circRNA named as Circ-TNPO3. We found Circ-TNPO3 was significantly down-regulated in gastric cancer tissues, and Circ-TNPO3 was able to suppress the proliferation and metastasis of gastric cancer cells in vitro and in vivo. We then preliminarily confirmed that Circ-TNPO3 could competitively bind miR-199a-5p and HuR, and regulate EMT related molecules such as E-cadherin, Snail1, et al. In current project, we plan to further clarify the competitively binding interaction between Circ-TNPO3 and miR-199a-5p or HuR, and identify its downstream signaling pathways, and study the biogenesis mechanism of Circ-TNPO3 by using overexpression or knock-down of Circ-TNPO3 expression, pull-down assay, RNA immunoprecipitation(RIP), luciferase report system. We will verify our hypothesis that Circ-TNPO3 can competitive bind miR-199a-5p and HuR protein, and regulate EMT process and metastasis of gastric cancer through mediating miR-199a-E-cadherin/Smad4 and HuR-Snail1/MMP-9 axis. Our study will provide new clues to elucidate the mechanism of metastasis of gastric cancer.

胃癌是我国发病率最高的恶性肿瘤之一，易转移，预后差，其转移机制尚不明确。环状RNA是一类新发现的非编码RNA，与肿瘤的发病密切相关。课题组前期鉴定出一个新的环状RNA： Circ-TNPO3，在胃癌中表达显著下调，且能抑制胃癌生长和转移。我们初步证实，Circ-TNPO3可同时结合miR-199a-5p和HuR蛋白，调控EMT相关分子（E-cadherin、Snail等）。本项目拟利用慢病毒、siRNA、pull-down、RIP、荧光素酶等方法，进一步阐明Circ-TNPO3与miR-199a-5p和HuR的竞争结合作用，并鉴定其下游信号通路和成环机制，以验证假说“Circ-TNPO3具有结合miRNA和蛋白的双重功能，通过调控miR-199a-E-cadherin/Smad4和HuR-Snail/MMP-9通路，影响EMT进程，调控胃癌转移”。这为进一步阐明胃癌的转移机制提供新思路。

胃癌是我国发病率最高的恶性肿瘤之一，易转移，预后差，其转移机制尚不明确。环状RNA是一类新发现的非编码RNA，与肿瘤的发病密切相关。本项目鉴定出一个新的环状RNA： circ-TNPO3，其在胃癌中表达显著下调，与胃癌的分化程度相关，且血浆circ-TNPO3也具有作为胃癌诊断标志物的潜力。体外和体内功能研究表明，circ-TNPO3具有抑制胃癌细胞转移和增殖的能力。在作用机制方面，研究证实，circ-TNPO3可以直接与RNA结合蛋白IGF2BP3结合，从而竞争减弱IGF2BP3蛋白稳定下游靶标MYC mRNA的作用，进而抑制MYC及下游靶基因SNAIL的表达。该研究为我们揭示了circ-TNPO3通过蛋白诱饵（protein decoy)的方式，调控IGF2BP3-MYC-SNAIL作用轴，发挥抑制胃癌转移和增殖的功能。此外，本项目后续探索了circ-TNPO3在其他肿瘤中的功能。我们发现circ-TNPO3在肾透明细胞癌ccRCC中表达显著下调，且能够显著抑制ccRCC细胞的转移和增殖。同时，我们利用RIP-seq，在胃癌中鉴定出一批与IGF2BP3结合的circRNAs，并证实circRNAs和IGF2BP3的结合互作在调控胃癌的发生与转移中起着重要作用。本项目为我们勾勒出胃癌中环状RNA的不同作用机制，以及环状RNA和RNA结合蛋白协同互作、共同调控肿瘤的作用模式，有助于阐明胃癌的发病机制，也为胃癌的治疗提供新的靶点。本项目按计划进行，进展顺利，共发表SCI论文 6 篇，新申请发明专利1项。获得“重庆市自然科学一等奖”；入选重庆英才·青年拔尖人才；在国内学术会议上进行6次会议报告；目前，培养毕业博士生1人、硕士生1人。培养在读博士后1名，博士生4名，硕士生7名。