snoRNA生物发生在HBx促进肝癌发生发展中的作用研究

Hepatitis B virus X protein plays an important role in the pathological process of chronic hepatitis B, as well as the development, carcinogenesis and.metastasis of hepatocellular carcinoma (HCC), but the molecular mechanism remains unclear. S-Adenosylmethionine (SAM), derived from methionine catabolism in all mammalian cells, is not only the principal methyl donor, but also a crucial event in the maintenance of hepatocytes differentiation status. Our previously studies showed that HBx could cause genome-wide aberrant DNA methylation by reducing the production of the steady-state SAM in HCC, which contribute to hepatocarcinogenesis and development. Furthermore, we found that HBx could induce snoRNAs dysregulation and overexpression of fibrillarin (Fbl) HCC. And also, the host gene of small nucleolar RNA (SNHG6) reduces the production of steady-state SAM. We hypothesized that HBx could induce the disorders of snoRNA biogenesis, which may responsible for the occurrence and development of hepatocellular carcinoma HCC through different snoRNA pathways. One of snoRNA, SNHG6 could promote genome-wide aberrant DNA methylation through inhibiting the production of the steady-state SAM. This study will investigated the potential relationship between snoRNA pathway and HBx expression in the hepatocarcinogenesis and development from the point of epigenetic view, and then we will analyze the effect mechanism of SNHG6 on the steady-state SAM level in HCC. These studies will enrich our understanding of the molecular mechanism of the carcinogenic effect of hepatitis B virus, and provide a theoretical basis for the molecular target therapy for HCC.

乙型肝炎病毒X蛋白（HBx）在慢性乙肝病理过程，和诱发肝癌的发生、发展到侵袭转移中，都发挥重要作用。生物甲基供体S-腺苷蛋氨酸(SAM)在维持肝细胞分化状态中起中心事件作用。我们既往发现HBx通过降低稳态SAM浓度引起肝癌细胞基因组异常甲基化而促进肝癌发展。在此基础上，发现HBx可以诱发多个小核仁RNA（snoRNA)及小核仁RNA结合蛋白表达失调；其中小核仁RNA宿主基因（SNHG6）与细胞稳态SAM产生存在关联。我们推测HBx诱发snoRNA生物发生失调通过不同的snoRNA通路多途径促进肝癌的发生发展，其中一条途径是通过SNHG6参与对肝癌细胞基因组异常甲基化的调控。本课题将从表观遗传学角度研究HBx与snoRNA通路的关系在肝癌发展中所起的作用，并用RNA-蛋白质互作分析研究SNHG6对细胞稳态SAM的调控机制。这将丰富我们对乙肝病毒致癌机制的认识，为肝癌的靶向治疗提供理论依据。

小核仁RNA（snoRNA）生物发生失调在HBV诱发肝癌发生发展过程中发挥重要作用。生物甲基供体S-腺苷蛋氨酸(SAM)在维持肝细胞分化状态中起中心事件作用。我们发现HBx可以诱发多个snoRNA失调；其中小核仁RNA宿主基因（SNHG6）与细胞稳态SAM产生存在关联。本课题证实SNHG6在HCC发生、发展过程中起着促癌基因的作用，SNHG6可以作为HCC患者预后不良的潜在预警指标。机制方面，SNHG6作为ceRNA通过竞争性结合miR-101-3p上调ZEB1的表达，诱导EMT的发生，促进HCC的侵袭转移。SNHG6还通过结合RNA结合蛋白UPF1调控TGF-β/Samd通路，进而影响HCC进程。我们的结果提示SNHG6可以作为抗HCC侵袭、转移治疗的潜在靶点。进一步，我们发现SNHG6通过miR-1297介导藕联的两条正反馈通路降低SAM浓度从而促使肝癌细胞维持在低甲基化状态，其中一条通路是SNHG6通过激活miR-1297/FUS通路来调节MAT1A信使RNA的核质穿梭，从而抑制MAT1A蛋白的表达。另一条通路是SNHG6通过抑制miR-1297与MAT2A的3'UTR区域的直接结合从而促进MAT2A的表达。此外，我们还发现小核仁RNA：ACA11 通过PI3K/AKT通路促进肝癌细胞的生长。富含亮氨酸重复序列G-蛋白偶联受体（Lgr5）通过PDCD5/P53通路诱导肝癌细胞上皮间质转化并抑制癌细胞凋亡，从而促进肝癌细胞对化疗药阿霉素的耐药性。长链非编码RNA GAS5通过调控vimentin表达影响肝癌细胞的凋亡，可以作为肝癌生存分析的一个独立预后指标。本课题将从表观遗传学角度研究多个snoRNA在HBV诱发肝癌发生发展中所起的作用，以及snoRNA通路是否参与HBx对细胞稳态SAM的调控而影响肝癌细胞基因组异常甲基化。这将丰富我们对乙肝病毒致癌机制的认识，为探 求肝癌的分子靶向治疗提供新的理论依据。