癌相关性成纤维细胞自噬作用对胃癌转移的影响及其机制的研究

Gastric cancer is the second leading cause of cancer death in our country for its poor prognosis. Tumor cell metastasis is one of the major obstacles in the way of gastric cancer therapy. Tumor metastasis is determined not only by tumor cells themselves but also by stromal cells, especially the cancer-associated fibroblast (CAF) around the tumor hypoxic microenvironment. Tumor cells were interacted with CAF in a paracrine or incretion manner. It has become clear that fibroblast was induced into CAF in hypoxia or the factors such as IL-1, TGFβ, PDGF secreted by the tumor cells. Otherwise, the secretion of SDF-1, VEGF, TGF-β, PDGF, MMP2, MMP9 from CAF could promote the tumor growth, angiogenesis, invasion and metastasis..Recently, a new paradigm "The Autophagic Tumor Stroma Model of Cancer." was proposed. In this model, breast cancer cells induce the generation of ROS, stable expression of HIF-1 α, activation of NF-κB in adjacent CAF. Oxidative stress in the CAF activates an autophagic program, and the degradation of caveolin-1(cav-1) leading to the production of recycled nutrients such as amino acid, fatty acid, nucleotide that can then be used as "fuel" to promote the anabolic growth and aggressive progression of tumor epithelial cells. .The caveolar marker protein cav-1 plays a role in the tumor cell migration. It was known that Cav-1 inhibits metastasis through suppression of the expression of integrinβ3 and the activation of FAK. It is also reported that upregulation of PDGF-BB、VEGF、IL-6、IL-10 in caveolin-1-/- null mammary stromal fibroblasts compared with wild type by the gene array. In addition, the decreased expression of cav-1 promotes the tumor metastasis in gastric cancer. So we speculate that the autophagy and degredation of cav-1 in CAF not only provide the fuel for the adjacent tumor cells, but also promote the tumor invasion and metasitasis. .In our study, fibroblast HEL cells were incubated under hypoxia for 48hr.Microarray analysis showed that the expression of genes related to the angionetensis, autophagy, metasitasis,such as VEGF, PDGF, PGIS,BNIP3 ect.was incresed in hypoxia ..The aim of this study is to establish of the "the Autophagic Tumor Stroma Model of Cancer"in gastric cancer and detect if autophagic program and degradation of cav-1 could promote the invasion and metastasis of gastric cancer.

肿瘤转移是导致胃癌预后不良的主要原因。肿瘤微环境基质细胞中的癌相关成纤维细胞（CAF）对肿瘤的侵袭和转移起着重要的促进作用。成纤维细胞在缺氧或肿瘤细胞分泌的因子刺激下转化为CAF。CAF可刺激相邻的肿瘤细胞生长，血管新生及转移。最新研究表明，肿瘤细胞可诱导邻接CAF的HIF-1α高表达和自噬，而CAF通过自噬产生的氨基酸，脂肪酸及核苷能为相邻肿瘤细胞提供能量，维持和促进肿瘤细胞生长。但是，CAF自噬作用对邻接肿瘤细胞的侵袭和迁移的影响尚不清楚。我们的研究显示成纤维细胞HEL在低氧状态下活化并发生自噬，且VEGF，PGIS，PDGF等因子表达升高。本研究拟通过成纤维细胞与胃癌细胞共培养，建立自噬性肿瘤基质的细胞模型及自噬性肿瘤基质的胃癌动物模型，探讨CAF的自噬作用对胃癌细胞侵袭及迁移功能的作用及其机制，研究结果可为明确自噬CAF调控胃癌转移的机制及治疗方法的开发提供重要依据。

肿瘤转移是导致胃癌预后不良的主要原因。肿瘤微环境中癌相关性成纤维细胞对肿瘤的侵袭和转移起着重要的作用。本项目用胃癌细胞与成纤维细胞共培养以模拟肿瘤微环境，探讨了单独培养及共培养系统中成纤维细胞分泌因子的变化及胃癌细胞转移能力的变化及机制，证实：1. 成纤维细胞与胃癌细胞共培养后，胃癌细胞muc1、fibronectin、MMP9、integrin β1等因子表达上调，MAPK和NF-κB通路活化，转移能力增强；成纤维细胞自噬作用增强。2. 成纤维细胞单独或与胃癌细胞共培养后进行表达谱分析，发现细胞因子-细胞因子受体通路变化最为显著。利用TCGA胃癌RNASEQV2数据集，应用多因素COX比例风险模型，对该通路中转移相关的IL11、TSLP等7个基因进行生存分析，仅CXCL12表达升高与不良预后具有相关性，提示胃癌微环境中的成纤维细胞分泌的CXCL12对于胃癌预后具有重要的作用。3. CXCL12/CXCR4在脂筏中，通过caveolin1与cMET进行cross-talk，激活STAT3/ZEB1，促进vimentin表达，抑制E-cad表达，从而促进胃癌细胞EMT；CXCR4与p-cMET表达双阳性与胃癌预后差具有良好的相关性，提示CXCL12及p-cMET在胃癌转移及预后中具有重要作用。4. CXCL12/CXCR4与EGFR cross-talk，激活SRC，同时活化的SRC反过来进一步促进EGFR磷酸化，形成正反馈环，共同激活下游的AKT和ERK通路，进而促进胃癌转移。本课题的研究成果提示胃癌微环境中癌相关性成纤维细胞分泌的CXCL12对胃癌转移及预后起着重要的作用；CXCL12除与其受体CXCR4结合发挥作用外，还可通过旁路激活cMET、EGFR及下游的AKT、ERK、STAT3等通路，共同促进胃癌转移。本研究结果将为进一步明确胃癌微环境中癌相关性成纤维细胞在胃癌转移及预后中的作用、尤其是CXCL12对胃癌转移的影响及其机制提供了有力的证据，并为靶向胃癌微环境的新靶点开发提供新的科学思路。