PLCE1及其反义RNA相互作用在食管癌发生发展中的机制研究

Esophageal squamous cell carcinoma (ESCC) is prevalent in certain parts of China. Although etiology of ESCC remains unclear, the individual's genetic makeup may play an important role in its carcinogenesis. We previously conducted a genome-wide association study (GWAS) of ESCC and identified PLCE1 on 10q23 as a susceptible gene for ESCC. However, the functions of PLCE1 and its variants were unknown yet. PLCE1-AS1, the antisense RNA of PLCE1, is also the transcript product by this region and has 130bp same sequence as the part of exon 20 of PLCE1. This overlap region is a CTCF binding site, which might work with PLCE1-AS1 to co-regulate PLCE1 expression. Fine-mapping of this region reveals several variants, such as rs2274223A/G and rs71031566ATTT/-, that might also play important roles to affect the functions or expressions of PLCE1 or PLCE1-AS1. Therefore, our study will not only focus on the identifications of functional variants which are associated with risk of ESCC, but also systemic certificate the functions PLCE1 in ESCC carcinogenesis through a series of biochemical assays. This is the first post-GWAS to conduct fine-mapping and functional characterization of the PLCE1 susceptible region. This study will extend our previous findings and advance the understanding of the genetic etiology of ESCC.

食管鳞状细胞癌是我国常见肿瘤，个人的遗传因素在食管癌发生中起重要作用。通过全基因组关联研究，申请者所在实验室发现位于10q23的PLCE1是食管癌的易感基因，然而PLCE1及其变异的生物学功能研究仍未见报道。通过序列分析，我们发现该区段同时表达PLCE1的反义RNA（PLCE1-AS1），与PLCE1第20外显子存在130bp的互补序列，该互补区段还是CTCF绝缘子的结合位点，可能共同调节PLCE1的表达。针对PLCE1基因座序列变异的精细分析，显示该区段存在rs2274223A/G、rs71031566ATTT/-等功能性遗传变异，可能调节PLCE1或PLCE1-AS1的功能或表达。本课题突破目前大多数全基因组关联研究只寻求发现易感基因（变异）的局限，通过对遗传变异及PLCE1-AS1功能及其与PLCE1相互作用的生物学机制研究，系统阐明PLCE1在食管癌发生发展中的重要作用。

食管鳞状细胞癌是我国常见肿瘤，个人的遗传因素在食管癌发生发展中起重要作用。本课题首先进行食管癌多组学测序，绘制了详细的食管癌基因组图谱。通过对全基因组关联研究的数据进行深入挖掘，发现PLCE1基因遗传变异与食管癌易感性相关。通过对PLCE1所在区段进行深度挖掘，发现位于PLCE1第22号内含子区的遗传变异rs71031566（CATTT插入/缺失）与ESCC风险显著相关（OR=1.28,95％CI=1.19-1.38; P=1.59×10-10）。通过一系列功能实验证明rs71031566 [CATTT]所在的内含子区包含增强子元件，通过转录因子Oct-2与PLCE1基因的启动子区接触，远距离调控PLCE1的表达。PLCE1是食管癌的抑癌基因，通过激活PLC-PKC抑癌信号通路，同时抑制PI3K-AKT促癌信号通路抑制肿瘤生长。在组学数据的基础上，我们同时对ADH基因家族所在的食管癌易感区段进行eQTL分析，发现rs1154402调节ADH1A基因的表达，可能是过度饮酒个体易患食管癌的功能基础。