旁分泌FGF相关的癌细胞及癌间质细胞THBS家族表达差异- - - - 弥漫性胃癌高侵袭性的新机制？

Compared with intestinal-type gastric cancer, diffuse-type gastric cancer owes stronger invasive ability， poorer prognosis and more abundant cancer stromal cells. Overcoming the high invasivess of diffuse gastric cancer cells may essentially improve its present poor outcomes of treatment. In our previous study, we found that FGF7 was paracrined by the abundant stromal cells, and its slective recptor, FGFR2-IIIb was over expressed in diffuse gastric cancer cells, while low expressed in cancer stromal cells. On the other side, by the analysis of immunohistochemistry and gene expression profile clustering in the done priliminary study,we found that diffuse gastric cancer cells were generally lack of THBS1 expression, while the expression of THBS4 was was primarily observed within the extracellular matrix surrounding the tumor cells, with the highest intensities found in regions of high tumor cell density and invasion. FGF7 pacarined by cancer stromal cells enhenced the invasion of diffuse gastric cancer cells and promoted the process of tumor angiogenesis.The active protein of THBS1 promoted the invasion of OCUM-2M, and inhibited the tumor angiogenesis. If the activity of FGFR2 in cancer cells inhibited by shRNA or by the inhibition of phosphorylation, the invasion was attenuated and the protein expresion of THBS1 in cancer cells was interestingly upregulated. According to the previous published data and results in our priliminary study, we proposed the following theoretical assumptions for our application: the expression difference of THBS family between diffuse gastric cancer cells and stromal cells potentially helps to synergisticly promote the invasion of diffuse gastric cancer cells,and it is assumpted that FGF7 paracrined by stromal cells possibly takes part in the invasive progress of diffuse gastric cancer by downregulation of THBS1. To prove our theoretical assumptions,we designs this research subject in various levles of tissues, cells and in vivo. We will use analysis of gene expression profile clustering, three-dimensional culture model, orthotopic human gastric carcinoma model to explore the correlation between the invasiveness and expression difference of THBS family relatd with the pacarine FGF7 in diffuse gastric cancer. Beside this, we want to explore the potential molucualr mechanism of THBS1 downregulation by FGF7 in diffuse gastric cancer cells, which perhaps will become a promising treatment target to attenuate invasiveness of diffuse gastric cancer.

弥漫型胃癌侵袭性高，预后差。我们发现：弥漫型胃癌富含的间质细胞旁分泌FGF7，其选择性结合受体FGFR2-IIIb在癌细胞上高表达，癌间质中表达很弱；而癌细胞THBS1低表达、癌间质THBS4高表达，且癌细胞密度越高、侵袭性越强的部位THBS4表达越强；THBS1可降低弥漫型胃癌细胞侵袭及移植瘤血管生长；FGF7显著增强弥漫型胃癌细胞的侵袭性并促进肿瘤血管新生，阻断FGFR2活性后，癌细胞THBS1表达增加，侵袭性减弱。据此我们推测：癌细胞THBS1低表达与癌间质THBS4高表达可能是弥漫型胃癌侵袭的协同促进机制；旁分泌的FGF7可能有负调控癌细胞THBS1表达的作用，而这种负调控作用可能是FGF7信号参与侵袭转移的分子机制之一。本申请项目拟在组织水平、细胞水平及体内水平验证上述理论设想，并初步探索FGF7负调控THBS1表达的可能分子机制，为弥漫型胃癌寻找治疗新思路。

FGFR2信号通路与胃癌的发生发展密切相关，是重要的靶向治疗相关靶点。FGF7是一种间质特异性的生长因子，可以结合并激活FGFR2进而调节多种细胞内外的生理过程。本研究旨在探索FGFR2信号通路在胃癌侵袭转移中的作用及其机制。胃癌组织芯片结果分析显示，FGFR2在胃癌组织中的表达明显高于癌旁组织，且与患者淋巴结转移、临床分期及预后密切相关。在体外实验中，FGF7可以促进胃癌细胞的侵袭转移，而当FGFR2表达下调时，FGF7的这种作用就会减弱。越来越多的文献表明，FGFR2在肿瘤中的功能与THBS蛋白家族密切相关。THBS在细胞间质与细胞之间的相互作用中起到重要作用。胃癌组织免疫组化分析显示，THBS1在胃癌组织中表达高于癌旁组织，而THBS4在胃癌组织中表达低于癌旁组织。THBS1的表达与胃癌分化程度密切相关，THBS4低表达的患者临床分期相对偏晚且OS较短。相关性分析发现，FGFR2与THSB1呈正相关性，与THBS4呈负相关性。FGF7处理的胃癌细胞，THBS1的表达上调，THBS4的表达下调，而当FGFR2的表达下调时，THBS1和THBS4均无明显变化。下调THBS1的表达，FGF7/FGFR2的促侵袭转移作用减弱，而下调THBS4的表达，FGF7/FGFR2的促侵袭转移能力增强。以上结果说明FGFR2对胃癌侵袭转移的作用是通过调控THBS1和THBS4实现的。通过使用一系列小分子通路抑制剂，我们发现FGFR2对THBS1和THBS4的调控主要是通过PI3K/AKT/mTOR通路实现的。以上对FGFR2通路的相关研究为FGFR2高表达的胃癌患者提供了新的治疗思路和治疗策略。