RNA去甲基化酶FTO在结直肠癌发生发展中的作用与机制研究

N6-Methyladenosine (m6A) modification is widely implicated in various biological processes. However, the role of m6A in human diseases, especially in cancer has not been well studied. In this study, we show that Fat mass- and obesity-associated protein (FTO), as m6A and m6Am demethylase, plays a vital oncogenic role in colorectal cancer (CRC). We found that knockdown of FTO using shRNA remarkably inhibited CRC cell proliferation, migration and invasion. Intriguingly, the FTO inhibitor meclofenamate sodium also significantly inhibited CRC cell proliferation. The analysis of RNA-seq revealed that the gens regulated by FTO were enriched in inflammatory responses, which were associated with TNF signaling pathway and NF-κB signaling pathway, such as IL-8, TNF, CXCL1, NFKB2, CCL20. Meanwhile, we also demonstrated that knockdown of FTO inhibited NF-κB activation and expression of pro-inflammatory cytokines and chemokines. Moreover, we found that FTO mRNA is highly expressed in CRC compared to normal tissues by data mining from TCGA database and UALCAN online data. Taken together, we proposed the hypothesis that FTO played an oncogenic role in CRC by NF-κB overactivation. Based on our initial results, we will explore the role and mechanism of FTO in CRC by using FTO-conditional knockout mice, PDX mouse model, intestinal organoids cultures, MeRIP-seq, CLIP-seq, RIP and other assays in vivo and in vitro. Up to now, the roles of FTO and m6A in CRC are unclear. This project will unveil the linking of ‘inflammation to cancer’ and eventually provide a new therapeutic target for CRC.

RNA m6A修饰广泛参与到各种生物学过程中，但其在人类疾病，尤其是癌症中的作用与机制尚未完全阐明。本项目已发现FTO具有促进结直肠癌发生发展的作用。FTO敲降后抑制结直肠癌细胞的增殖、迁移和侵袭。FTO抑制剂能够抑制结直肠癌细胞的增殖。RNA-seq数据分析发现FTO敲降显著下调炎症相关分子的表达，FTO调控的基因主要富集于TNF和NF-κB信号通路。并且FTO敲降后抑制NF-κB的活化。TCGA数据分析显示结直肠癌患者癌症组织中FTO表达升高。基于上述结果，我们提出“FTO通过维持NF-κB的异常活化而诱发结直肠癌”的假说。为证实我们的假说，本项目拟采用FTO条件敲除小鼠、PDX模型、肠类器官培养、MeRIP-seq、CLIP-seq、RIP等各种体内、外技术方法研究FTO在结直肠癌中的作用与机制。本项目将会进一步阐述“炎-癌”转化的机制，并为结直肠癌的治疗提供新的理论依据和治疗靶点。

RNA m6A修饰广泛参与到肿瘤的发生发展过程中，但在结直肠癌中的作用与机制尚未完全阐明。本研究证实m6A去甲基转移酶FTO具有促进结直肠癌发生发展的作用。FTO在结直肠癌肿瘤组织的表达显著高于正常组织，并且m6A在结直肠癌肿瘤组织的表达低于正常组织。我们通过体内体外实验表明敲降FTO抑制结直肠癌细胞的增殖、迁移和侵袭，而且FTO抑制剂能够显著抑制结直肠癌细胞的增殖。我们发现FTO能够促进蛋白翻译，结合Ribo-Seq、MeRIP-Seq和LFQ蛋白组学等多组学数据分析发现FTO选择性促进5’TOP mRNA翻译。因此，我们证实FTO能够促进结直肠癌发生发展，并为结直肠癌治疗提供新的理论依据和治疗靶点。