胆管细胞癌相关RNA编辑的鉴定及其功能机制研究

肝内胆管细胞癌（iCCA）约占肝脏原发恶性肿瘤的10%-15%。目前针对iCCA的临床治疗手段极其有限，而且关于其发生进展的分子机制的理解仍非常局限。RNA编辑是遗传信息转录后加工修饰的一种重要形式。目前尚未见在iCCA中关于RNA编辑的研究报道。本研究前期通过开展iCCA转录组和基因组整合分析全面地绘制了RNA编辑图谱，并发现了一个位于E3泛素连接酶KPC1上的新的非同义编辑位点。初步研究发现此编辑位点在iCCA中发生由ADAR1介导的过编辑；KPC1在iCCA细胞中发挥抑癌功能，而其编辑体表现出功能缺失；表达谱分析提示KPC1可能通过参与调控NF-κB信号通路活性发挥抑癌作用。本研究拟在此基础上，深入阐明KPC1 RNA编辑的肿瘤生物学功能、揭示其分子机制并探究其临床相关性。期望通过此研究，从转录后调控层面为阐明iCCA发生发展机理提供理论依据，为防治iCCA的药物研发提供候分子靶标。

The intrahepatic cholangiocarcinoma (iCCA) is the second most common primary liver cancer (PLC), accounting for 10-15% of all PLCs. Despite the relative low incidence of iCCA, it deserves urgent attention because the worldwide incidence of this malignancy has been increasing steadily and substantially over the past four decades. In addition to genomic alterations, RNA editing is another recently described epigenetic mechanism in which sequence alterations are introduced into the genome-encoded RNA transcripts, while leaving the underlying genome intact and unmodified. To date, however, the role of ADARs and the landscape of RNA-edited targets in iCCA remains unknown. In this study, to gain an insight into the landscape of RNA editing in iCCAs, we performed an integrative whole-exome and transcriptome sequencing analysis on 15 pairs of iCCA tissues and their matched adjacent non-tumor liver tissues. Further, using an exemplary target gene Kip1 ubiquitination-promoting complex 1 (KPC1), we discovered an ADAR1-mediated recoding RNA editing event causing an amino acid substitution from methionine (Met) to valine (Val) at codon 8 of KPC1 (p.M8V). Our preliminary functional studies showed that wide-type KPC1 could significantly suppress the proliferation and migration of cholangiocarcinoma cell lines, while the RNA editing conferred a loss-of-function phenotype. Additionally, KPC1 may act as a tumor suppressor by inhibiting NF-κB pathway. Furthermore, we will determine the tumorigenic roles of the newly identified A-to-I editing of KPC1 by both in vitro and in vivo assays, and then investigate whether and how KPC1 RNA editing affects cell proliferation and migration by regulating NF-κB pathway. The aim of this study is to clarify the molecular mechanism of KPC1 RNA editing in the development of iCCA, and our results may highlight RNA editing as another mechanism of sequence alteration contributing to iCCA progression, and provide potential targets for treatment of this malignancy.