白介素 17A 介导 IL6/STAT3 活化促进胃癌发展的机制研究

Inflammation is closely related to cancer, known as "the seventh hallmark of cancer". Interleukin (IL)17A is a strong pro-in?ammatory cytokine, which plays important roles in initiating and sustaining inflammation, however, the role of IL17A in tumor development is still controversial. Our previous study found that: IL17A polymorphisms increased risks of certain subtypes of gastric cancer, and IL17A over expressed in gastric cancer tissues, moreover, recombinant human IL17A protein could promote gastric cancer cell proliferation and inhibit apoptosis, which also induced IL6 expression in a concentration-dependent manner. Considering that IL6 can work through the JAK/STATs pathway, activating STAT3, which has emerged as key regulators of both inflammation and cancer. We thus speculated that the high expression of IL17A may mediate the activation of IL6/STAT3 pathway to promote the development of gastric cancer.This project intends to further experiment in vitro and in vivo, using gene transfection, RNA interference, Real-time PCR, western blot et all,to confirme the role of IL17A in promoting gastric cancer development and its activation role on IL6/STAT3 pathway. Furethermore, using carcinogen MNNG-induced rat gastric cancer model, to study IL17A-mediated IL6/STAT3 activation in the role of formation of chronic inflammation - precancerous lesions and gastric cancer induced by chemicals. These studies provide a theoretical basis that inflammatory factor IL17A is involved in gastric cancer, which ultimately provide an experimental basis for finding new targets in clinical treatment for gastric cancer.

炎症与癌症的关系密切，被称为"癌症的第七大特征"。IL17A是强促炎因子, 在炎症的激发和维持中起重要作用，但其在肿瘤中的作用仍未明确。前期研究发现：IL17A 多态性与国人胃癌的发病风险有关，其蛋白在胃癌组织中高表达，重组人 IL17A 蛋白刺激可促进胃癌细胞增殖、抑制凋亡，并促进 IL6 表达。鉴于IL6可通过 JAK/STATs 的途径，活化 STAT3，后者是联系炎症与肿瘤的重要调控器，我们推测：IL17A 高表达促进胃癌的发生发展，并可能与其介导 IL6/STAT3 通路活化有关。本项目拟通过体内体外实验，证实IL17A的促瘤作用；分析 IL17A 对IL6/STAT3 通路的活化作用；并通过致癌剂MNNG诱导的大鼠胃癌模型，研究IL17A在癌前病变以及胃癌形成中的作用。为炎症因子 IL17A参与胃癌发病提供理论依据，并最终为临床上寻找胃癌治疗的新靶点提供实验基础。

炎症与肿瘤的关系密切。胃癌的发生被认为与Hp感染相关的慢性胃炎有关。IL17A是CD4+Th细胞分泌的强促炎症因子，在炎症的激发和维持中起重要作用，然其在肿瘤中的作用仍未明确。前期研究发现IL17A 基因多态性与国人胃癌的发病风险有关。本研究中，我们进一步通过体内体外实验，探讨IL17A促进胃癌发展的证据及其可能的机制。我们先通过免疫组化检测了胃癌组织中IL17A蛋白表达情况，发现IL17A蛋白在胃癌组织中的表达显著高于癌旁胃黏膜组织（P=0.007），且主要表达于肿瘤组织中浸润的炎症细胞以及血管内皮细胞。进一步检测IL17A蛋白与VEGF及CD34在胃癌组织中表达的相关性，发现IL17A与VEGF表达以及CD34染色呈正相关，提示其可能参与胃癌血管生成。在体外实验中，我们筛选出IL17R/VEGF共表达细胞系AGS，分别采用Western Blot和ELISA法，用不同浓度IL17A蛋白处理，发现IL17A能显著促进AGS细胞VEGF表达，且结果呈现较好的量效关系；此外，IL17A处理AGS细胞能显著促进stat3及p-stat3表达。进一步采用成小管实验，我们发现IL17A处理AGS细胞，其上清液中VEGF以及stat3,p-stat3表达显著升高，该上清液能显著促进脐带血上皮细胞小管形成；加用JSI-124特异性阻断p-stat3后，能显著降低VEGF表达以及小管形成。最后，我们成功构建了IL17A过表达稳定细胞系，将IL17A过表达AGS细胞及对照AGS细胞分别接种裸鼠，构建荷胃癌裸鼠模型，并同时给予JSI-124 (1 mg/kg/day) 腹腔内注射，结果显示IL17A促进裸鼠体内种植瘤生长，并能促进肿瘤组织中VEGF，CD34表达，用JSI-124特异性阻断p-stat3后，VEGF的表达以及肿瘤体积均受显著抑制。以上结果提示我们：IL17A可通过激活stat3信号通路进而上调VEGF表达，促进血管生成及胃癌发展。JSI-124特意性阻断stat3活化，能显著抑制上述作用，提示其有潜力成为胃癌治疗的新靶点。