m6A甲基转移酶METTL3调控5'-isomiR-1261生成促进口腔鳞癌恶性进展的机制研究

研究证实，体内大多数高丰度表达的miRNA异构体（isomiRs）具有重要的生物学功能，许多疾病的致病机制与isomiRs的表达变化密切相关。人类口腔鳞癌中有关isomiRs的研究尚未见报道。我们前期研究发现：（1）口腔鳞癌组织中5'-isomiR-1261显著升高，并促进癌细胞的增殖、克隆形成及抑制细胞凋亡；（2）pri-miR-1261转录本中存在m6A修饰位点；（3）口腔鳞癌中METTL3基因表达升高，沉默METTL3表达导致RNA m6A修饰及5'-isomiR-1261表达水平降低。基于以上结果，我们提出假设：METTL3介导的RNA m6A修饰调控5'-isomiR-1261的合成，促进口腔鳞癌的发生发展。我们拟通过miCLIP及RNA测序等方法，在分子生物学、PDX模型以及临床样本等不同层面，深入研究isomiRs形成的分子机制及临床诊治价值，开辟isomiRs研究的新视野。

It is known that almost all miRNAs have isomiRs. Most high-abundance isomiRs in the body have important biological functions. The pathogenic mechanism of many diseases is closely related to isomiRs. Research on isomiRs in human oral squamous cell carcinoma (OSCC) has not been reported. Our previous research found that 5'-isomiR-1261 was significantly increased in oral squamous cell carcinoma tissues, and that the targets regulated by 5'-isomiR-1261 were significantly different from targets regulated by typical miR-1261. 5'-isomiR-1261 significantly promotes the proliferation, colony formation, and reduces the incidence of apoptosis of OSCC cells. Studies have initially confirmed that m6A modification exists in the pri-miR-1261 transcript. In addition, METTL3 gene expression was increased in OSCC tissues, and silencing of METTL3 gene expression resulted in a decrease in 5'-isomiR-1261 expression level. Based on the above results, we propose a scientific hypothesis: METTL3-mediated RNA m6A modification regulates 5'-isomiR-1261 biosynthesis and promotes the occurrence and progression of oral squamous cell carcinoma. We intend to use miCLIP, MeRIP-qPCR, RNA pull-down, and RIP methods to deeply study the molecular mechanism of isomRs formation and its clinical diagnostic and therapeutic value at different levels such as cell biology, PDX models, and clinical samples. Simultaneous research at the miRNA/isomiR level will help to further understand miRNA biosynthesis and precise regulation models, and open up new fields for miRNA research.