胃癌MSC源性细胞因子调节Th17/Treg细胞分化作用机制及其临床应用

We have previously demonstrated that bone marrow mesenchymal stem cells (BMMSCs) could promote tumor growth. We have also successfully isolated mesenchymal stem cells from gastric cancer tissue (GC-MSCs)which showed more potent than BMMSCs in promoting tumor growth. We recently found that GC-MSCs could induce the differentiation of CD4+ T cells into Th17／Treg cells in vitro, while the number of Th17 cells and the levels of related cytokines were also significantly increased in both tumor tissue and peripheral blood of gastric cancer patients, indicating that Th17 cells may associate with the development and progression of gastric cancer. However, the exact mechanism involving Th17 and GC-MSCs is unknown. In this project we will seek the key specific factors in GC-MSCs that induce Th17/Treg cell differentiation by using the Luminex assay,and other cellular and molecular biology approaches, and further delineate the mechanisms by which tumor growth is promoted . The effect of GC-MSCs induced Th17/Treg cells in gastric cancer will be investigated both in vitro and in vivo. Together with the detection of key cytokines in the tumor tissue as well as in blood circulation (or in exosomes), we will formulate a new panel of biomarkers, and evaluate their clinical values in diagnosis, prognosis and treatment of gastric cancer.

我们前期研究证实骨髓间质干细胞（BMMSCs）体内能促进肿瘤生长，并从人胃癌组织分离到胃癌间质干细胞（GC-MSCs），研究表明GC-MSCs具有较BMMSCs更强的促肿瘤生长能力。近期我们发现GC-MSCs具有诱导CD4＋T细胞向Th17细胞分化的能力，并发现胃癌病人肿瘤组织及外周血中Th17细胞及相关因子表达明显增多，表明Th17细胞与胃癌的发生发展密切相关。但胃癌微环境中GC-MSCs 与Th17细胞的作用机制及在胃癌发生发展中的作用还不清楚。本课题将采用Luminex芯片及细胞分子生物学技术筛选出GC-MSCs调节Th17/Treg细胞分化的关键因子及探讨其作用机制。体内外观察GC-MSCs诱导的Th17/Treg细胞在胃癌发生发展中的作用，并结合临床胃癌患者肿瘤组织及血浆（或exosomes）关键细胞因子的检测，评价其临床应用价值，为胃癌的诊断、预后判断和治疗提供新的分子标志。

我们前期研究证实骨髓间质干细胞（BMMSCs）体内能促进肿瘤生长，并从人胃癌组织分离得到胃癌间质干细胞（GC-MSCs）。研究表明GC-MSCs 具有较BMMSCs 更强的促肿瘤生长及转移能力，但其具体作用机制不清。本研究采用细胞生物学及分子生物学技术体内外观察GC-MSCs诱导Th17/Treg细胞分化及对胃癌细胞生长的作用及机制，筛选GC-MSCs 诱导Th17/Treg 细胞分化的关键分子。建立人源化免疫系统小鼠皮下移植瘤模型，研究GC-MSCs对胃癌生长作用及免疫调控机制。结合临床胃癌患者肿瘤组织及血清标本检测，探讨GC-MSCs 调节Th17/Treg 细胞关键因子在临床胃癌患者诊断中的特异性，评估其在疗效观察及预后判断中的应用价值。结果发现GC-MSCs上清（GCMSC-CM）诱导后外周血单个核细胞（PBMC）条件培养上清可以促进小鼠皮下瘤的增殖及转移， GCMSC-CM能促进PBMC中Treg 细胞分化，抑制Th17分化。研究表明GCMSCs较BMMSCs具有较强的产生IL-15的能力，胃癌组织中基质细胞是IL-15的主要来源，GCMSCs来源的IL-15促进CD4+T细胞STAT5的磷酸化水平升高进而上调Treg细胞的比例及Treg细胞表面PD-1的表达。临床胃癌患者肿瘤组织及血清中IL-15高表达，且与淋巴结转移有关。人源化免疫系统小鼠皮下移植瘤模型研究发现GCMSCs可以有效促进小鼠外周血及肿瘤组织Treg细胞和Th17细胞比例增高。研究还发现GCMSCs来源的IL-8通过STAT3-mTOR信号调节胃癌细胞PD-L1表达，并促进胃癌细胞抵抗PD1抗肿瘤免疫。结果提示，GCMSCs来源的IL-15促进CD4+T细胞向Treg 细胞分化，并通过分泌IL-8上调肿瘤细胞PD-L1抑制肿瘤免疫，促进肿瘤生长和转移。研究结果将为临床胃癌的诊断、预后判断和治疗提供新的分子标志，为临床胃癌的肿瘤免疫治疗提供新的分子靶点。