FTO介导的m6A去甲基化在婴幼儿血管瘤发生发展中的作用与机制研究

Infantile hemangioma (IH) is the most common benign tumor in infancy, and approximately 50% of untreated hemangiomas have accelerated tumor growth, resulting in multiple organ dysfunction and risk of facial deformities. Currently, there are still great controversies about inducing factors, rapid proliferation and natural involution mechanism of IH. The applicant’s previous study found that the level of m6A demethylase FTO was significantly up-regulated in hemangioma cells, while inhibition of FTO could induce increased apoptosis of hemangioma cells. Meanwhile based on the research it suggested that the increase of adipocytes differentiated from hemangioma stem cells might be an important cause of hemangioma entering the involuting phase. We have detected that exosome miRNA from the plasma of patients in the involuting phase could act on hemangioma cells and down-regulate FTO expression. Based on the previous research, this project aims to reveal the function and the detailed mechanism of FTO-mediated epigenetic changes in the progression and involution of hemangiomas, and to analyze whether the exosome secreted by the adipocytes differentiated from hemangioma stem cells could promote the apoptosis of hemangioma endothelial cells and accelerate the hemangioma into the involuting phase. This project will provide novel concepts for the IH progression mechanism and potential new approaches for the treatment of IH.

婴儿血管瘤(IH)是婴儿期最常见的良性肿瘤，其增殖与消退的机制仍不明确，自行消退这一特殊现象提示表观遗传调控可能起到重要作用。申请人前期研究发现，在增殖期IH中m6A去甲基化酶FTO升高，而抑制FTO能够诱导血管瘤内皮细胞的凋亡；同时发现消退期患者血浆外泌体内miR-155表达上调，可明显下调FTO，而研究提示血管瘤干细胞成脂分化导致的脂肪细胞增加可能是血管瘤进入消退期的重要诱因。基于此我们提出假说：在增殖期FTO介导的RNA m6A去甲基化修饰可上调增殖及抗凋亡基因，促进IH的进展；而在消退期脂肪细胞外泌体下调FTO表达，抑制抗凋亡基因，从而诱导内皮细胞凋亡。我们拟通过体内、体外、临床三个层面，揭示FTO介导的RNA m6A去甲基化修饰在血管瘤增殖和消退期的功能，探讨并阐明其作用的具体机制；同时分析脂肪细胞外泌体促进内皮细胞凋亡加速IH进入消退期的机制，为血管瘤的治疗提供的新的思路。

婴幼儿血管瘤（IH）是婴儿期最常见的良性肿瘤，其增殖与消退的机制仍不明确。血管瘤干细胞（HemSCs）在IH的发生、快速增殖、消退过程中扮演着重要角色。外泌体（Exosome）是一种细胞外分析的膜性小囊泡，在调节干细胞与细胞外微环境交流的细胞间信号转导过程中起着重要作用。本项目以HemSCs为研究的核心细胞，探究其增殖消退的相关调控机制。.构建负载miR-187-3p的工程化hAMSCs的E-exos后通过体外管腔形成实验和MTT实验评估E-exos对HemSCs的增殖抑制作用，并验证了Notch信号通路在miR-187-3p对HemSCs增殖抑制作用过程的调控作用。获取临床增殖期血管瘤组织，通过HE染色和免疫组化实验发现了有药物治疗史和无治疗史的血管瘤组织结构出现差异，标志物的表达发生变化。此外，研究发现婴幼儿血管瘤对药物的耐药性与M2型巨噬细胞外泌体有关，通过增殖实验以及动物体内实验验证了M2-exos对血管瘤的调控作用。通过构建FTO干扰慢病毒，感染人脐静脉内皮细胞(HUVECs)并筛选转染稳定株细胞用于后续实验研究。构建FTO-MO斑马鱼动物模型，初步发现斑马鱼表型发生变化，通过转录组测序发现相关基因表达发生变化。.以上研究结果为后续血管瘤相关研究奠定了基础，为婴幼儿血管瘤的治疗提供新的思路。