白头翁皂苷重塑免疫微环境抑制PD-L1介导的肿瘤免疫逃逸的分子机制研究

肿瘤免疫微环境和PD-L1是免疫抑制导致肿瘤免疫逃逸的两个主要因素。抗PD-L1药物已开始广泛应用，但其临床响应率等还存在很大挑战，靶向肿瘤免疫微环境治疗日益受到重视。STAT3既可以调控肿瘤免疫微环境，又能直接调控PD-L1转录，被认为是很有潜力的一个靶点。课题组研究发现，白头翁皂苷既可以抑制STAT3磷酸化，调控肿瘤微环境中的免疫细胞和因子；又可以下调MC38细胞PD-L1的表达，抑制MC38结肠癌小鼠的肿瘤生长，且对正常结肠上皮细胞没影响，由此推测白头翁皂苷抗肿瘤和STAT3/肿瘤微环境/PD-L1有关。因此，本项目以此为主轴，先通过体内外实验观察白头翁皂苷对STAT3，肿瘤微环境和PD-L1的影响及对肿瘤免疫逃逸的抑制作用；再利用造血干细胞STAT3条件敲除小鼠，基因突变，过表达等技术进行分子水平验证，阐明其抑制肿瘤免疫逃逸的分子机制，为免疫抗肿瘤新药研发提供理论基础。

Tumor immune microenvironment and PD-L1 are the two main factors that lead to tumor immune escape due to tumor immunosuppression. Anti-PD-L1 drugs have begun to be widely used, but their clinical response rate and side effects are still very big challenges. Targeting tumor immune microenvironmental therapy is receiving more and more attention.STAT3 can dually regulate the tumor microenvironment and directly regulate PD-1 at the transcription level, which is considered to be a promising target. Traditional Chinese medicine has a good overall regulatory effect, but the mechanism of traditional Chinese medicine in tumor microenvironment/PD-L1 is insufficient studied. Our previous research showed that Pulsatilla Saponin can inhibit STAT3 phosphorylation, and it can also regulate inflammatory cytokines and immune cells in the tumor microenvironment. Recently, it has been found that Pulsatilla saponins showed a promising anti-tumor effect on MC38 colon cancer mice and have no effect on normal human colon epithelial cells. At the same time, it can also down-regulate the expression of PD-L1 in MC38 cells, It is speculated that Pulsatilla Saponins regulate PD-L1 to anti-tumor through Stat3 pathway. Therefore, taking STAT3/tumor microenvironment/PD-L1 as the main axis, this project firstly observe the effect of Pulsatilla saponins on Stat3, tumor microenvironment and PD-L1 and the inhibitory effect on tumor immune escape by in vivo and in vitro experiments; and then to verify the molecular mechanism at the molecular level by using hematopoietic stem cells STAT3 conditional knockout mice, gene overexpression or other technologies, this project intends to provide a solid theoretical basis for the promising immune anti-tumor new drug development.