去甲基化酶FTO介导FSTL1 mRNA的m6A去甲基化而促进胃癌细胞的侵袭和迁移

Gastric cancer is one of the most common and devastating malignancies in China. FSTL1 was known to be associated with cancer development, but its functions regulatory mechanisms in gastric cancer remain elusive. Recent studies have shown that FTO may have an important role in promoting the occurrence of gastric cancer. However, the impact of FTO, especially as a RNA demethylase, in tumor progression of gastric cancer remains unclear. We discovered that FSTL1 expression increases in gastric cancer and predicts poor survival in patients. FTO inhibition decreased the invasion and migration of gastric cancer cells, while over-expressing FSTL1 rescued these repressive effects. The FTO-reducing lines exhibit a decrease in FSTL1 mRNA level and a noticeable increase in m6A level. Accordingly, we hypothesize that FTO, as an m6A demethylase, promotes the invasion and migration of gastric cancer cells by reducing the m6A levels of FSTL1 mRNA and enhances FSTL1 expression. Based on our previous study,the relationship between FTO/FSTL1 and clinical and pathological parameters of gastric cancer would be determined by analyzing the tissue microarray of gastric cancer. Moreover, the functions of FTO/FSTL1 would be clarified in the model of gastric cancer lines and nude mice, and the underlying mechanism would be uncovered by using Transcriptome sequencing and Methylated RNA Immunoprecipitation technology. The present study aims to provide novel targets for the diagnosis and treatment of gastric cancer.

胃癌在我国发病率高，预后差。FSTL1被报道与肿瘤进展有关，但在胃癌中作用及调控机制不明。FTO被报道可能促进了胃癌的发病，但是否作为RNA去甲基化酶发挥作用未知。我们发现：FSTL1在胃癌中高表达，并与患者预后负相关。敲减FTO抑制胃癌细胞的侵袭和迁移，同时过表达FSTL1则挽救此抑制作用。敲减FTO下调FSTL1 mRNA的表达，却提高FSTL1 mRNA的m6A水平。据此，我们假设去甲基化酶FTO介导FSTL1 mRNA的m6A去甲基化而上调FSTL1的表达，进而促进胃癌细胞的侵袭和迁移。本研究拟在前期基础上，利用组织芯片评估FTO和FSTL1的表达与胃癌临床病理参数的相关性，在细胞模型和裸鼠模型中明确其功能，并应用转录组测序和甲基化RNA免疫共沉淀等技术阐明其作用机制，以期为胃癌的诊疗提供新靶点。

背景：据报道，胃癌（GC）中脂肪质量和肥胖相关蛋白（FTO）的表达增强。生物信息学研究表明，FTO表达与患者的总生存率（OS）相关。FTO如何对GC开发产生促进作用并影响OS，这在很大程度上仍是未知的。在这项研究中，研究了FTO在人GC组织中表达的预后相关性以及FTO促进作用的分子机制。..方法：用免疫组织化学（IHC）分析人GC组织芯片中FTO的表达，然后评估其表达状态与预后的关系。使用FTO敲除和过度表达，在体外和小鼠异种移植模型中研究了FTO对GC细胞恶性表型的促进作用。进行高通量转录组测序以鉴定差异表达基因和相关信号通路。..结果：Kaplan-Meier生存曲线分析显示，与低FTO表达的患者相比，高FTO水平的患者的OS更短（p<0.0001）。单变量和多变量COX回归分析显示，患者的OS受FTO状态的影响（分别p<0.0001，p=0.001）。通过shRNA敲低HGC27细胞中的FTO可减少细胞增殖、集落形成、迁移和侵袭，而AGS细胞中FTO过表达具有相反的作用。HGC27细胞中的FTO敲除也抑制了小鼠异种移植模型中的肿瘤生长。高通量转录组测序表明，FTO增强了PI3K/Akt信号传导，这在体外得到了证实。..结论：FTO是一种有效的GC预后生物标志物。FTO增强PI3K/Akt信号传导，从而促进GC的发展。