DEK环状RNA在肝癌中的鉴定及其功能机制研究

Circular RNA (circRNA) is a type of RNA that forms a covalently closed continuous loop. Recently, circRNAs are found to be widespread and highly abundant due to the high-throughput sequencing and novel computational approaches. They have been categorized as noncoding RNA with potential as gene regulators. However, the expression, function and mechanism of circRNAs in human cancer remain largely unknown. In this study, we had identified a set of circRNAs differently expressed in hepatocellular carcinoma (HCC) by using high-throughput RNA sequencing. One of these circRNAs, derived from exon3-9 of DEK, was found to be significantly downregulated in HCC. Patients with low levels of circDEK had a significantly shorter survival time than those with the high levels of circDEK. In contrast, DEK mRNA was upregulated in HCC. Patients with high levels of DEK mRNA had a significantly shorter survival time than those with the low levels of DEK mRNA. Furthermore, functional assay by RNA interference indicated that circDEK could inhibit HCC cell migration. CircDEK derived from oncogene may act as tumor suppressors in HCC. In this project, we will expand the current knowledge regarding molecular mechanisms involved in HCC onset and progression, with potential diagnostic and therapeutic implications.

环状RNA(Circular RNA)是一类非线性，自身成环的RNA分子。近年来随着RNA高通量测序和生物信息学技术的发展，大量环状RNA被发现，并且具有潜在调控基因表达的作用，但是环状RNA在肿瘤中的表达情况、临床意义以及功能机制仍不清楚。本课题前期通过高通量RNA测序分析鉴定了一批肝癌相关的环状RNA，其中环状RNA circDEK由癌基因DEK的3号到9号外显子环化形成。然而，circDEK的表达与宿主基因DEK相反，在肝癌组织中显著下调，并且与预后相关；初步实验结果显示circDEK可显著抑制肝癌细胞的迁移，提示circDEK在肝癌中可能行使着与宿主基因DEK不同的功能。本课题将在前期基础上，深入研究circDEK在肝癌中的功能及其作用机制，为肝癌的发病机制提供新的思路，以及肝癌的诊疗提供新的候选靶点。

环状RNA(Circular RNA) 是一类非线性RNA分子，是非编码RNA研究领域的热点。近年来随着RNA高通量测序和生物信息学技术的发展，研究者发现大量包括环状RNA在内的非编码RNA广泛存在于真核生物的细胞中，并且具有潜在调控基因表达的作用，但是环状RNA在多种肿瘤中的表达情况、临床意义以及功能机制仍不清楚。我们开发了新的分析工具ASJA (Assembling Splice Junctions Analysis)。 通过此工具对高通量RNA测序分析（RNA sequencing, RNA-seq）鉴定了一批肝癌相关的环状RNA及其它非编码RNA，并且鉴定到环状RNA circDEK在肝癌病人的血清中低表达，其宿主基因mRNA在血清中高表达。环状RNA circDEK由癌基因DEK的3号到9号外显子环化形成。circDEK在肝癌组织里的表达情况也与宿主基因DEK不同，在肝癌组织中显著下调； circDEK抑制肝癌细胞的迁移，提示circDEK在肝癌中发挥抑癌作用，行使着与宿主基因DEK不同的功能。我们通过 RNA Pull down 实验，捕获与circDEK相互作用蛋白为肿瘤转移抑制蛋白LASS2蛋白。环状RNA circDEK发挥抑癌作用是通过稳定LASS2蛋白发挥促转移作用，这提示环状RNA及肝癌相关非编码RNA可作为肿瘤液体诊断和治疗的靶点。环状RNA circDEK在肝癌血清外泌体中低表达。同时，我们通过对肝癌血清外泌体测序，发现了一类肿瘤特异的转录本，我们将其中一个命名为TST1。包括TST1在内的大量非编码RNA可作为诊断和治疗的靶点。本课题为肝癌的诊断治疗提供新的思路及多个候选靶点。.