FAM84B在食管鳞癌发生中的作用机制及临床意义研究

Esophageal squamous cell carcinoma (ESCC) is the main type of esophageal cancer in China. Currently, there's no effective biomarker for early screening. FAM84B, its copy numbers dramatically increased in ESCC, is one of the most important early-stage related genes. Furthermore, FAM84B is highly expressed in the early of ESCC and the precancerous lesions，and promoted significantly the proliferation, invasion and migration of ESCC cells. However, its molecular mechanism in tumorigenesis of ESCC is unclear. Our previous microarray result showed that FAM84B deregulated the downstream targets of TGF-β pathway. Additionally, it was implicated that FAM84B interacted with SMAD4 in other researches, the key component involved in TGF-β pathway. Therefore, we hypothesize that FAM84B regulates the TGF-β signaling pathway by interact with SMAD4 to promote the initiation of ESCC. It has been reported that the mRNA expression level of FAM84B in peripheral blood was correlated with the expression of tissues. It might be a potential biomarker for the early of ESCC and the precancerous lesions. This proposal aims to research the role and mechanisms of FAM84B in ESCC by luciferase reporter experiments and protein interaction analysis. In addition, we study the value of early screening for ESCC by detecting the level of FAM84B mRNA in peripheral blood of patients. The project will provide a theoretical basis for understanding the carcinogenesis of ESCC and finding early screening molecular markers.

食管鳞癌是我国高发肿瘤之一，目前缺乏有效的早期筛查标志物。FAM84B基因是我们通过前期组学测序发现的拷贝数显著增加的早期相关基因，在食管鳞癌及癌前阶段显著高表达，并促进食管鳞癌细胞增殖、侵袭和迁移，但其在食管鳞癌发生中机制尚不明确。基因芯片结果显示FAM84B表达水平影响肿瘤早期转化相关信号通路TGF-β的下游基因水平，文献报道FAM84B与该通路关键分子SMAD4可能存在相互作用，故推测FAM84B可能通过SMAD4调节TGF-β信号通路进而促进食管鳞癌发生。已报道外周血FAM84B mRNA水平与组织表达水平相关，可能提示食管鳞癌癌前病变并预警食管鳞癌易感性。本项目拟通过蛋白互作、荧光素酶报告实验等研究FAM84B在食管鳞癌发生中的作用和机制，通过检测患者外周血FAM84B mRNA研究其作为食管鳞癌早期筛查指标的价值，为理解食管鳞癌早期致癌机制和寻找早期分子标志物提供理论基础。

食管鳞癌是中国的特色恶性肿瘤，预后相对差，目前的治疗手段是手术结合传统放、化疗，缺乏早期发现和精准治疗的分子靶标。 FAM84B基因是我们通过全基因组测序发现的拷贝数显著增加的8q24区域中的候选癌基因，实验验证了其在食管鳞癌及癌前阶段显著高表达，并显著促进食管鳞癌细胞增殖、侵袭和迁移，但其在食管鳞癌发生发展中的作用机制尚不明确。本项目通过在食管鳞癌细胞系中用MTT、Transwell、流式细胞术等方法检测稳敲和稳转FAM84B基因后细胞增殖、侵袭迁移、细胞周期等功能，发现FAM84B对食管鳞癌具有促癌作用，并通过调节细胞周期促进增殖；通过质谱鉴定随FAM84B表达改变的蛋白结合数据库筛选，IF、Co-IP和GST-pull down验证，明确了FAM84B与NPM1基因具有直接相互作用；通过文献筛选、WB验证，确定FAM84B/NPM1通过CDKN2A分子影响CCND1、P21等细胞周期相关蛋白表达，进而影响细胞周期进程。本项目选择食管鳞癌基因组中的拷贝数发生高频变异的8q24区域中的基因进行研究，首次完整揭示了候选癌基因FAM84B在食管鳞癌中作用机制，有希望找到针对特定人群的诊断和治疗标志物，为完善ESCC的发生机制和进一步精准治疗提供帮助。