环状RNA circ-MGA结合并调控YTHDF2识别mRNA甲基化在膀胱癌中的作用及机制研究

The importent role of circRNA in progression of human disease has been gradually recognized in recent years，and it's function and mechanism still need to be further explored. Currently, circRNA is considered playing biological role mainly through acting as "molecule sponges", including combining with RNA binding protein. Recent studies show that circRNAs could regulate gene expression through participating the regulation of DNA or RNA methylation. Based on the circRNA expression profile of bladder cancer through RNA-seq, we confirmed the differential expression of circRNA in bladder cancer and the role in inhibiting bladder cancer progression. Our preliminary data showed circ-MGA could bind to YTHDF2. This study will further reveal the role and mechanism of circ-MGA/YTHDF2 interaction in regulating MMP-9 expression, and clarify the molecular mechanism of circ-MGA that regulates mmp-9 methylation through YTDHF2; Furthermore, we will establish circ-MGA stable overexpression/restraint system, and explore the role of circ-MGA on the biological function of YTHDF2/MMP-9 pathway in bladder cancer. This work will provide a novel strategy for targeted therapy and inhibition of invasion and metastasis in bladder cancer.

环状RNA在疾病发生发展中的重要作用逐渐被广大研究者认可，其功能及作用机理仍需进一步研究探讨。目前认为，circRNA主要作为“分子海绵”发挥生物学作用，包括结合RNA结合蛋白。新近研究表明，环状RNA可通过参与调控DNA或RNA甲基化发挥基因调控功能。我们在前期获得高通量测序表达谱基础上，首次鉴定并确定了circ-MGA在膀胱癌组织中的差异性表达，其在膀胱癌中起抑癌作用。初步研究显示：circ-MGA具有结合甲基化特异性识别蛋白YTHDF2的功能。本研究拟进一步解析circ-MGA结合YTHDF2对MMP-9表达的调控作用及机制，深入剖析circ-MGA通过YTHDF2调控mmp-9甲基化的分子机制；通过建立circ-MGA过表达/抑制体系，探讨circ-MGA调控YTHDF2/MMP-9通路对膀胱癌生物学行为的影响，旨在为抑制膀胱癌侵袭转移、转移性膀胱癌靶向治疗提供新策略。

膀胱癌是最常见的泌尿系统恶性肿瘤之一，其具有易复发、耐药性、易浸润、对放化疗不敏感等特性，不断发掘和阐明膀胱癌发生发展的作用机制，寻找新的、有效的、安全的作用靶点，是膀胱癌靶向治疗获得突破的关键，以此为基础的靶向治疗策略是提高患者生存率及生存质量的又一重要途径。环状RNA作为重要生物调控分子，其在多种人类肿瘤的发生发展中发挥着举足轻重的生物调控作用。circRNA具有可通过多种作用方式发挥生物学功能，如“miRNA分子海绵”、结合RNA结合蛋白、参与基因转录、编码蛋白、参与蛋白折叠及参与表观遗传学等。本项目通过对高通量测序数据的进一步挖掘，发现环状RNA circMGA、circ ARHGAP12、circPLEKHM3在膀胱癌组织中显著下调，然而进一步的反复细胞验证实验并未发现circ-MGA其对膀胱癌细胞的增殖、凋亡、周期及侵袭有显著影响。进一步的研究显示，HNRNPL可提高circMGA、CCL5的稳定性，并增强CCL5 mRNA的稳定性，同时通过增加CCL5 3’UTR活性，上调CCL5的表达。而更深一步的研究显示，circMGA/HNRNPL复合物可通过上调CCL5的表达加强CD8+ T细胞渗透入膀胱癌组织间隙，发挥肿瘤细胞杀伤作用。而初步研究显示ARHGAP12、circPLEKHM3对膀胱癌增殖、侵袭等均有一定的抑制作用，更深一步的机制探索将在后续进一步研究中深入解析。本项目阐释了新的膀胱癌生物学行为的作用机制，为膀胱癌的靶向治疗策略提供了新理论、新依据。