S100P调节胰腺癌免疫逃逸的作用机制研究

S100P is highly expressed in pancreatic cancer, breast cancer, colon cancer and lung cancer and so on, and it can promote tumor growth and metastasis. But its effect on regulating the tumor immune microenvironment has not been reported. We found that the pancreatic cancer cell line BxPC-3 which has high expression of S100P can inhibit the dendritic cells (DC) differentiation and maturation through enhancing the expression of IL-6 and G-CSF in cancer cells. However, another pancreatic cancer cell line Panc-1 which has low expression of S100P meanwhile has low expression of IL-6 and G-CSF do not have the same effect on DC differentiation and maturation. We also interestingly found that S100P can upregulates Panc-1 cell express IL-6 and G-CSF, and stimulate DC secretion of IL-6 and IL-10. S100P can be secreted from the cell. Meanwhile, IL-6 and G-CSF are the important factors in activating and recruiting myeloid-drived suppressor cell (MDSC). As prescribed, we propose that S100P may regulate tumor immune microenvironment directly or indirectly, promotes the tumor immune escape and therefore mediates the development, progression and metastasis of tumor. This proposal will focus on the roles of S100P in regulating DC, MDSC, TAM, Th and Treg cells in vitro and in vivo in pancreatic cancer microenvironments. The significance of this proposal is will uncover the mechanism of S100P in regulating tumor immune escape, and provide a new way for S100P associated tumor prevention and tumor immunotherapy.

S100P在胰腺癌、乳腺癌、肠癌和肺癌等多种癌症中高表达，可促进肿瘤生长和转移。但其对肿瘤免疫微环境的调节作用尚无报道。我们发现S100P高表达的胰腺癌细胞系BxPC-3可通过高表达IL-6和G-CSF抑制树突细胞（DC）分化和成熟；而S100P低表达的胰腺癌细胞系Panc-1同时低表达IL-6和G-CSF不具有这些功能。我们还证明S100P可上调IL-6、IL-10和G-CSF。IL-6和G-CSF也是激活和招募髓系抑制细胞（MDSC）的重要因子。而且S100P可分泌于细胞外。因此，我们认为S100P可间接和/或直接调节肿瘤免疫微环境，打破免疫监视平衡，促进肿瘤发生发展或转移。本项目将应用体内和体外实验研究S100P对胰腺癌免疫微环境中的DC、MDSC、辅助T细胞和调节T细胞等免疫细胞和因子的调节作用机制。揭示S100P调节肿瘤免疫逃逸的作用机制，为相关肿瘤预防和免疫治疗奠定基础。

S100P在胰腺癌、乳腺癌、肠癌和肺癌等多种癌症中高表达，可促进肿瘤生长和转移。但其对肿瘤免疫微环境的调节作用尚无报道。我们研究发现，S100P高表达的胰腺癌细胞系BxPC-3可通过高表达IL-6和G-CSF抑制树突细胞（DC）分化和成熟。预示着S100P可间接和/或直接调节肿瘤免疫微环境，促进肿瘤发生发展或转移。.本项目首先利用高/低表达S100P的Panc-1、Panc02和Bxpc3细胞系，发现S100P对肿瘤细胞中IL-6、GM-CSF、G-CSF等炎症因子的表达具有明确的调控作用。进一步在体内研究S100P对小鼠胰腺癌免疫微环境的调控作用，结果发现S100P可能明显促进MDSC、巨噬细胞、Treg细胞的募集活化，降低γδT细胞比例，明显升高肿瘤组织内分泌IL-17A的Th 细胞，而对分泌IFN-γ和IL-4的Th细胞无明显变化。.进一步体外研究了S100P对肿瘤免疫微环境中的MDSC、TAM、DC等免疫细胞和因子的调节作用及机制。首先，利用人外周血单个核细胞（PBMC）分化模型研究高/低表达S100P的胰腺癌细胞培养上清、S100P重组蛋白对MDSC、TAM、DC分化及功能的影响。利用流式细胞术、Western blot、实时定量PCR及ELISA等手段，分析MDSC、TAM、DC细胞表面标记物、细胞因子分泌、MDSC、TAM、DC细胞的功能酶表达以及针对MDSC细胞抑制CD8+T细胞功能及相关信号分子的变化。利用STAT3抑制剂FLLL32深入研究了STAT3在S100P调节MDSC分化过程的作用。结果表明S100P高表达的胰腺癌细胞上清液以及S100P重组蛋白可促进MDSC分化，并增强MDSC对T细胞抑制功能。胰腺癌细胞可能通过分泌S100P直接作用于MDSC或者通过S100P上调IL-6等细胞因子表达间接促进MDSC分化和功能。免疫组织化学检测发现胰腺癌患者肿瘤组织中S100P表达和CD33+ MDSC相关。同时发现S100P对巨噬细胞和DC细胞的极化分化和功能也具有一定的影响，其具体的分子机制还有待深入研究。.此研究显示S100P高表达后会打破肿瘤免疫平衡，促进免疫抑制细胞分化和激活，进而促进胰腺癌免疫逃逸。本研究为以S100P为靶点的相关肿瘤预防和免疫治疗提供了理论基础和实验依据。