HBV整合位点MYC/PVT1与肝癌早发的关联和作用机制研究

The hepatitis B virus （HBV）genome integration is widely found in HBV-related hepatocellular carcinoma (HCC). But the relationship between the integration and the age of HCC onset has not been studied exhaustively, and the mechanisms of the integration in tumorigenesis and metastasis have not been elucidated clearly either. In the previous study, we used a new high-throughput detection of viral integration method (HIVID), and found that the HBV integration hotspot MYC/PVT1 was associated with the age of HCC onset, and the related gene: a long non-coding RNA PVT1 over-expressed in early-onset of HCC. Thus, we intended to further verify the relevance of this integration site and the early onset of HCC and the prognosis in larger samples firstly, and then to explore the epigenetic mechanism of HBV integration in affecting PVT1 gene expression. At last, we investigate the effect of PVT1 on several biological characteristics (eg, proliferation or apoptosis) of hepatoma cells in vitro and vivo. The aim of our project is to verify the assumption that the HBV integration site MYC/PVT1 could promote early onset of HCC by regulating the expression of PVT1. Our researches are helpful to clarify the pathogenesis of early onset of HCC, and may reveal the risk factors in the young HBV carriers for HCC, so that it can provide theoretical support for searching for therapeutic targets and warning markers of early-onset HCC.

乙型肝炎病毒（HBV）相关的肝癌组织中普遍存在HBV基因组整合的现象，但是其与肝癌发病年龄的关系未见系统研究，对肝癌发生、发展、转移过程的影响机制也尚未阐明。本项目组在前期研究采用一种新的高通量病毒整合检测方法（HIVID）进行筛选，发现HBV整合热点MYC/PVT1与肝癌发病年龄有关，并且该热点相关基因：长链非编码RNA PVT1在早发性肝癌中异常高表达。本项目中拟首先扩大样本验证该位点与肝癌早发的关联和与患者临床预后的相关性，而后探讨HBV整合对PVT1基因表达的表观遗传调控机制，最后在体外细胞、体内裸鼠动物模型中探讨PVT1对于肝癌细胞增殖、凋亡等生物学特性的影响和作用机制，从而验证课题假设：HBV在MYC/PVT1位点的整合通过对PVT1的表达调控促使了HBV-HCC的早发。本课题研究有助于阐明肝癌早发的发病机制，并为寻找早发性肝癌早期诊断、治疗新靶点提供理论基础和方向。

早发和晚发性肝癌中，乙肝病毒（HBV）整合不同。我们前期通过高通量筛选发现，HBV整合在MYC/PVT1位点与肝癌早发有关联。该位点相关基因PVT1在早发性肝癌中异常高表达，其表达水平与肝癌病人的生存期负相关。PVT1的自身调控机制研究发现，其能够剪切形成circPVT1，通过发挥ceRNA的功能,从而减弱let-7的抑癌作用。功能实验研究发现，干扰PVT1能够在细胞和裸鼠体内显著抑制肝癌细胞的增殖、迁移和转移，而过表达能够促进Wnt通路分子Wnt1和上皮-间质转化标志分子N-cadherin、Snail的表达，与此同时，circPVT1表达增加和抑制能部分逆转该趋势。本项目阐明了HBV在MYC/PVT1位点的整合通过对PVT1的表达调控促使了肝癌早发，探索了circPVT1通过发挥ceRNA的功能促进肝癌增殖、转移的分子机制，并为寻找早发性肝癌早期诊断、治疗新靶点提供理论基础和方向。