NRPTPs基因家族功能性遗传变异的发掘及其与肝癌发病风险的相关性研究

Hepatocellular carcinoma (HCC) is characterized by inconspicuous initiation, rapid progression and high fatality, seriously threatening the life and health of our people. Identifying molecular markers for early screening of HCC high-risk population is an important means to effectively prevent and control this cancer. Non-receptor protein tyrosine phosphatases (NRPTPs) play a key role in many important activities including cell growth, proliferation and apoptosis. Their functional deficiency is closely related to the initiation and development of HCC. First, we systematically screened potentially functional single nucleotide polymorphisms (SNPs) within NRPTPs gene family and identified candidate SNPs that impact on gene expression or protein function. Second, we carried out a large case-control study including 1600 HCC patients and 1600 match controls to investigate the association between candidate SNPs and the susceptibility to HCC, and focused on the potential gene-gene interaction as well as gene-environment interaction. Finally, we performed a series of experiments in vitro and in vivo to further uncover the pathogenic mechanism of HCC-related SNPs, and explored their feasibility to predict the HCC risk. In the post-GWAS era, our study not only provides a new approach to excavate the association of genetic variants with HCC risk, but also provides promising molecular markers to screen HCC high-risk population, which has important theoretical and practical significance for early detection and treatment as well as individualized prevention and control of HCC.

肝癌发病隐匿、进展迅速、病死率高，严重危害我国人民的生命健康，寻找早期筛查的分子标志物是有效防控肝癌的重要手段。非受体型蛋白酪氨酸磷酸酶（NRPTPs）在细胞生长、增殖和凋亡等生命活动中发挥关键作用，其功能缺陷与肝癌发生发展密切相关。我们首先利用生物信息学系统性发掘NRPTPs基因家族的潜在功能性遗传变异，筛选出其中最可能影响蛋白功能（编码区变异）和干扰基因表达（调控区变异）的候选位点；然后通过1600对大样本病例-对照研究揭示候选位点与肝癌易感性的关系，分析基因-基因、基因-环境交互对肝癌发病的影响；最后采用体内和体外实验阐明肝癌易感性相关位点的致病机制，并探讨其预测肝癌发病风险的可行性。在“后GWAS时代”，本项目不仅为深入研究肝癌遗传病因提供了新思路和方法，所揭示的功能性遗传变异还有望作为分子标志物用于肝癌高风险人群的早期筛查，对肝癌的早诊早治和个体化防控具有重要的理论和现实意义。

非受体型蛋白酪氨酸磷酸酶（NRPTPs）的功能缺陷与多种癌症发病密切相关。我们首先通过生物信息学系统性发掘17个NRPTPs基因家族成员的潜在功能性遗传变异，筛选出其中最可能影响蛋白功能（编码区变异）和干扰基因表达（调控区变异）的候选位点。然后我们采用病例-对照研究，通过Sequenom-MassARRAY平台，对790例肝癌病例和1454例匹配对照进行候选位点的基因型分型。人群结果显示，PTPN4 rs9308777和PTPN12 rs3750050与中国人群肝癌发病风险显著相关。对于PTPN4 rs9308777，平均每增加一个风险等位基因A，肝癌发病风险上升25%（Adjusted OR = 1.25, 95%CI = 1.06-1.49, P = 0.009）。对于PTPN12 rs3750050，平均每增加一个风险等位基因G，肝癌发病风险上升26%（Adjusted OR = 1.26, 95%CI = 1.10-1.45, P = 0.001）。两位点存在累加效应，平均每增加一个风险等位基因，肝癌发病风险升高27%（Adjusted OR = 1.27, 95%CI = 1.14-1.41, P = 2.40×10-5）。未发现这两个位点与吸烟或饮酒的统计学交互，也未发现它们与HBV持续感染风险的统计学关联。最后我们通过功能实验进一步揭示，PTPN4 rs9308777可能通过下调PTPN4基因表达增加了肝癌易感性；PTPN12 rs3750050显著削弱了PTPN12磷酸酶活性，可能通过上调p-EGFR和p-ERK导致MAPK-ERK通路的异常磷酸化，从而促进细胞增殖，增加了肝癌易感性。本研究为深入研究肝癌遗传病因提供了新的线索和依据，发现的PTPN4和PTPN12有望作为新的易感基因用于肝癌高风险个体的早期筛查和个体化防控。