PI3K/Akt/mTOR信号通路在胃癌中的表达与调节机制及其意义

Genomics / Proteomics / Environmental epidemiology methods was performed to explore the effect and mechanism of PI3K/Akt/mTOR signal pathway in the development of gastric carcinoma from the level of cells, tissues and the population respectively.The study will provide academic evidence for the prevention and treatment of stomach cancer by gene level and the intervene of high risk groups. (1) The expression level of key signaling molecules such as PI3K、Akt、mTOR in PI3K/Akt/mTOR signal pathway was analyzed in gastric cancer cells and normal gastric epithelial cells, and the expression differences and regulation mechanism of the above-mentioned signaling molecules in different cell lines were explored. (2) We aim to detect the influence of target molecule inhibitors on the proliferation,apoptosis and the expression of key protein of gastric cancer cells.(3)We will explore PI3K/Akt/mTOR signaling pathways regulating the molecular mechanisms of gastric cancer susceptibility genes overexpression. (4)The expression level of key signaling molecules involved in this signal pathway in the gastric cancer tissue, adjacent tissue and normal tissue from patients with different clinical and pathological features was analyzed. The exome sequencing technology was performed to detect the changes of mTOR exon in gastric cancer and adjacent tissues, further to explore the relationship between them. (5)The Case-control study will be conducted to analyze the expression of the key signaling molecules involved in this signal pathway in peripheral blood mononuclear cells, and analyze the interaction between the expression differences of key signal molecule and environmental risk factors.

采用基因组学/蛋白组学/环境流行病学方法，分别从细胞、组织及人群水平探讨PI3K/Akt/mTOR信号通路在胃癌发生、发展中的作用及机制，为基因靶向治疗及干预措施提供学术依据。(1)分析胃癌细胞和正常胃黏膜上皮细胞中PI3K/Akt/mTOR通路中PI3K、Akt、mTOR等关键信号分子的表达情况，并分析上述信号分子的表达差异及调控机制；（2）考察靶分子抑制剂对胃癌细胞的增殖、凋亡、关键蛋白表达的影响作用；（3）探讨PI3K/Akt/mTOR信号通路调控胃癌易感基因过表达的分子机制；（4）分析不同病人胃癌组织、癌旁组织、正常组织中该通路关键信号分子的表达情况，采用外显子测序技术分析胃癌及癌旁组织中mTOR外显子的变化，探讨其与胃癌的关系；（5）采用病例-对照研究方法，分析人群外周血单核细胞中该信号通路关键信号分子的表达情况，并分析这些关键信号分子表达差异与环境危险因素的交互作用。

信号转导通路的异常改变与肿瘤的发生、发展、转移、预后及化疗敏感性密切相关，基于信号通路的临床抗癌抑制剂的研究一直是热点。本课题组前期研究结果显示，PI3K、AKT、mTOR等通路关键信号分子在胃癌中高表达，通路处于异常激活状态。为了更进一步了解PI3K/AKT/mTOR信号通路在胃癌中的表达与调节机制，本项目从细胞水平、组织水平及人群水平探讨PI3K/Akt/mTOR信号通路在胃癌发生、发展中的作用及机制，结果如下：（1）MGC-803、BGC-823、SGC-7901细胞中PI3K、AKT、mTOR、P70S6K、PTEN、4EBP的mRNA与正常胃粘膜细胞GES-1相比显著升高， PI3K/AKT/mTOR信号通路在胃癌细胞中处于激活状态。（2）LY294002和雷帕霉素可抑制胃癌细胞MGC-803、BGC-823、SGC-7901中信号通路关键信号分子的表达，可降低细胞增殖率、改变细胞周期比例、促进细胞凋亡；（3）PTEN、p-AKT、p-mTOR蛋白在胃癌组织、癌旁组织及正常胃黏膜组织中的表达阳性率具有差异；p-AKT、p-mTOR蛋白在浸润深度达到浆膜层的胃癌中阳性表达率要高于癌组织未浸润到浆膜层者；（4）mTOR的rs3806317位点等位基因频率在胃癌病人和正常人群中分布具有统计学差异，C等位基因的人群患胃癌的风险是T等位基因人群的0.568倍；（5）CYP2E1通过调节mTOR的磷酸化进而调控PI3K/Akt/mTOR信号通路下游70S6K（Ser371）和4EBP-1位点的蛋白活化，从而影响胃癌细胞的增殖、周期、凋亡、侵袭、迁移能力； LY294002能够促进胃癌细胞中CYP2E1的mRNA表达，降低CYP2E1的蛋白表达；（6）联合运用mTOR抑制剂rapamycin和MEK抑制剂PD98059相比单独用药能更显著的抑制细胞关键基因的转录和翻译过程，并促进细胞凋亡及细胞周期阻滞，从而抑制细胞生长。