候选癌基因GNA13调控外泌体促进食管鳞癌转移的作用及分子机制研究

Distant metastases are the main causes for the deaths of the patients with esophageal squamous cell carcinoma (ESCC). We have previously reported that GNA13 acted as an oncogenic protein involved in gastric, colorectal and liver cancer cell tumorigenesis and metastases. However, little is known about GNA13 expression and its clinical significance in ESCC. Recently, we found GNA13 was highly expressed in ESCC and closely associated with tumor metastasis. Furthermore, functional study revealed that overexpression of GNA13 could enhance ESCC cell metastasis by regulating exosome-induced microenvironment. However, the mechanisms of GNA13 regulated exosome in metastasis process of ESCC have not been elucidated. In this project, a series of technologies, including gene silencing, overexpression, miRNA array, luciferase gene reporter assay, mice metastasis model and co-culture, will be performed to verify and identify the function and mechanisms of GNA13 enhancing ESCC cell metastasis by regulating exosome, and exosomal miRNAs regulated by GNA13 in ESCC plasma will be tested to explore whether expression of exosomal miRNAs is associated with ESCC metastasis, in order to discover new molecular markers for predicting ESCC metastases and potential therapeutic targets for ESCC.

远处转移是食管鳞癌（ESCC）患者死亡的主要原因。本课题组前期研究已揭示GNA13在胃癌、肠癌及肝癌中的致瘤和转移机制；但是GNA13在食管鳞癌中的表达及其临床意义尚未报道。我们通过预实验发现ESCC中GNA13的高表达与转移有关；进一步的体内外功能预实验显示：GNA13过表达可通过外泌体诱导成纤维细胞转化调控组织器官微环境进而增强ESCC细胞侵袭转移。但GNA13调控外泌体促进ESCC细胞转移的具体分子机制尚不清楚。本项目将进一步通过基因沉默及回补、miRNA芯片、双荧光素酶报告基因、动物转移模型、共培养等技术来确证GNA13调控外泌体促进ESCC细胞转移的作用及分子机制，并检验血清中GNA13调控的exosomal miRNAs表达水平是否与ESCC转移相关，以期望发现预测ESCC转移的新的分子标志物和治疗ESCC可能的靶点。

本课题组前期研究已揭示GNA13在胃癌、肠癌及肝癌中的致瘤和转移机制，但GNA13在食管鳞癌中的表达及其临床意义尚未报道。我们通过预实验发现ESCC中GNA13在食管癌中呈高表达状态，且与食管癌不良预后相关；功能实验显示GNA13过表达可通过外泌体诱导成纤维细胞转化调控组织器官微环境进而增强ESCC细胞侵袭转移。通过比较和分析GNA13导入和沉默后与对照组相比共同涉及的外泌体源性差异miRNAs，我们采用real-time PCR验证出差异明显的miRNA。进一步采用生物信息学软件（TargetScan）分析miRNA的下游靶基因（SLC34A2、NCF2、IMPDH2等），并用双荧光素酶报告基因实验验证。我们发现SLC34A2在食管癌中高表达，SLC34A2过表达可增加食管癌细胞的增殖能力，并进一步证实SLC34A2通过PI3K/AKT/mTOR通路促进食管癌细胞增殖。这些发现将为GNA13高表达的食管鳞癌患者提供新的治疗靶点。