长链非编码RNA与胃癌易感性的分子流行病学研究

In recent years, genome-wide association studies (GWAS) of gastric cancer have revealed many important genetic variations in relation to gastric cancer susceptibility. However, the quantity on GWAS of gastric cancer was very limited, and GWAS was difficult to identify the causal genetic variations. Thus, it is needed for us to take advantage of the GWAS data of gastric cancer, and explore the potential causal genetic variations related to gastric cancer. Long non-coding RNA (lncRNA) is a research hot spot at present, several studies have shown that genetic variation in lncRNA could modulate the expression of lncRNA or other target genes through certain underling mechanism, and further affect the risk of gastric cancer. Nevertheless, these studies only focused on some candidate lncRNA and were not systematic. Therefore, we bring forword a hypothesis that the identified genetic variations in lncRNA by GWAS data mining can alter the expression of lncRNA itself or other target genes, and ultimately affect the risk of gastric cancer. In this study project, firstly, on the basis of the gastric cancer genome-wide association study data (totally, 3771 cases of gastric cancer and 5426 controls) we already had and the public biological information data sources (such as TCGA and GTEx), we will systematically analyze and select genetic variations in lncRNA related to gastric cancer susceptibility; secondly, we will use a large-scale case control study to validate the association of the selected genetic variations with gastric cancer susceptibility, and than we will verify the differential expression level of candidate lncRNA; thirdly, we will conduct biological function prediction and functional experiments to explore functions of the genetic variations and the related lncRNA during the progress of gastric cancer occurrence and development, and reveal the underlying biological mechanisms. The results of our study project will help us to comprehend the pathological mechanism of gastric cancer and search for new effective methods to prevent and treat gastric cancer.

近年来，胃癌全基因组关联研究（GWAS）发现了一些重要的胃癌易感位点。然而，由于胃癌GWAS研究数量较少且GWAS很难发现真正的致病位点，因此我们仍需挖掘胃癌GWAS数据，探寻胃癌致病位点。长链非编码RNA（lncRNA）是目前研究热点之一，研究表明lncRNA相关遗传变异通过调控lncRNA及靶基因的表达进而影响胃癌发病风险，然而，这些研究仅仅关注少数候选lncRNA，尚缺乏系统性。因此，我们假设：基于GWAS数据系统挖掘确定的lncRNA遗传变异可以改变lncRNA自身及靶基因的表达，最终影响胃癌发病风险。本项目首先基于3771例病例和5426例对照的胃癌全基因组关联研究数据，结合TCGA等公共数据系统筛选与胃癌发病相关的lncRNA遗传变异；其次进行大样本人群易感性关联验证，然后验证候选lncRNA的差异表达；最后通过功能学研究探讨易感位点及相关lncRNA在胃癌发生中的生物学机制。

胃癌是危害全球人类生命和健康的常见恶性肿瘤之一。而在中国，因为胃癌所导致的健康负担已经超过了全球胃癌疾病和死亡负担的40%。除了人们所熟知的幽门螺旋杆菌杆菌感染、高盐饮食、吸烟、喝酒等环境危险因素以外，遗传因素也会影响胃癌的发生发展过程。全基因组关联研究已经发现了一系列重要的胃癌易感性相关的单核苷酸多态性位点（SNPs），这些位点主要位于8q24、10q23、3q13.31、5p13.1、6p21.1、1q22等区域。然而，所有已经发现的遗传位点也仅仅能解释少部分的胃癌遗传度。因此需要进一步探索那些胃癌易感性相关的遗传因素。本研究以GWAS数据为研究基础，通过利用多个胃癌GWAS数据探索长链非编码RNA（lncRNA）以及其他遗传分子标志物对胃癌发生发展过程的影响。本研究内容主要包括两个部分，一部分为探讨lncRNA遗传变异与胃癌发病风险的关系，并通过功能性研究探索可能的生物学机制；第二部分主要是利用胃癌GWAS数据资源和网络公共数据资源，探索可能的潜在胃癌分子标志物。主要研究成果包括以下几个方面：一、我们发现并验证出4个SNPs与胃癌发病风险有关，分别是位于SNHG7的rs968511 (OR=1.24, 95CI%=1.11-1.38)，位于LINC01082的rs276971 (OR=1.18, 95CI%=1.06-1.31)，位于FENDRR的rs4445918 (OR=1.19, 95CI%=1.02-1.38) and 位于NRAV 的rs2243616 (OR=1.12, 95CI%=1.01-1.24); 二、通过siRNA和ASO敲除NRAV可以削弱胃癌细胞的增殖和迁移能力并且影响裸鼠异种移植肿瘤的形成，RNA-seq和通路富集分析表明在降低NRAV的表达后，其下游的共表达基因（PFKP, PSPH, PSGDH和PSAT1）会明显富集在代谢通路上；三、我们使用基因组注释的多标记分析法（MAGMA）来分析胃癌GWAS数据，确定了三条与胃癌风险相关的通路，分别为趋化因子信号通路、钾离子导入通路和白细胞介素-7通路，白细胞介素-7通路的NMI和趋化因子信号通路的RAC1在胃癌组织中高表达，可能与胃癌的病理性过程有关。我们的研究成果给胃癌的病因学研究提供了一定的基础信息，为进一步探索胃癌的诊断和治疗方案提供了新的科学证据。