基于PI3Kγ介导的肿瘤微环境重塑探讨益气健脾化瘀法治疗胃癌的分子机制

The MengHe Medical sect believes that"the asthenia of the vital Qi"is the root cause of the gastic cancer, and"Blood stasis"is an important factor contrbuting to this disease. According to the basic pathogenesis of gastric cancer, we used"Qi-invigorating ,Spleen-strengtheningand Stasis-removing"formula in treating gastric cancer initially, which showed good efficacy in clinical and animal models. But it was inefficient in vitro. Therefore, we speculate that this formula may inhibit gastric cancer cells by regulating the tumor microenvironment. Immunosuppression in tumor microenvironment is a key factor of achieving tumor immune evasion, and abnormal activation of immune checkpoint is another major reason for aggravating micrenvironment immunosuppression. The latest study found that PI3Kγ on tumor-associated macrophages (TAM) could be used as a new immune checkpoint , the inhibitor of which didn’t kill the tumor cells directly but inhibit tumor growth by reducing immunosuppression in tumor microenvironment. At the same time, our previous experiments found that this formula could reduce the expression of PI3K and mTOR on TAM. Accordingly, this study aims to illustrate the effect of PI3Kγ on the immune microenvironment of gastric cancer through animal model of transplanted tumor of gastric and co-culture model. We also intend to work out the way that the"Qi-invigorating ,Spleen-strengtheningand Stasis-removing"formula suppresses gastric cancer based on this mechanism. This study will help to discover the new target for the treatment of gastric cancer, reveal the significance of"Qi-invigorating, spleen-strengtheningand stasis-removing"formula in treating gastric cancer, as well as provide a new method for Chinese medicine with tonic effect in treating cancers.

孟河医派认为“正气亏损”是胃癌发病之本，在此基础上“瘀毒内结”形成胃癌。根据胃癌本虚标实的病机，我们前期工作以“益气健脾化瘀”立法，发现该法对临床患者及动物模型疗效确切，但体外对胃癌细胞仅有轻微增殖抑制作用，故推测该法可能通过调节肿瘤微环境而抑瘤。肿瘤免疫抑制的微环境是肿瘤免疫逃逸的关键，而免疫检查点异常激活又是加重微环境免疫抑制的重要原因。最新研究发现肿瘤微环境中巨噬细胞（TAM）上PI3Kγ可作为新的免疫检查点，其抑制剂不直接杀伤肿瘤细胞的情况下，重塑微环境，抑制肿瘤生长。且我们预实验发现本治法指导下的中药组方能降低TAM上PI3K、mTOR表达。因此本课题拟通过胃癌移植瘤动物模型及共培养细胞模型，明确PI3Kγ对胃癌免疫微环境的影响，及基于该机制下“益气健脾化瘀”法干预胃癌的具体环节。本课题有利开发胃癌治疗新靶点，诠释健脾养正化瘀法治疗胃癌的科学性，为扶正类中药治疗肿瘤提供新思路。

“益气健脾化瘀法”是治疗胃癌的重要原则。免疫抑制的微环境是肿瘤免疫逃逸的关键，免疫检查点异常激活又是加重微环境免疫抑制的重要原因。本研究通过离体、在体实验，借助实时定量PCR、western blot、流式细胞术、免疫荧光、CBA等技术和挽救实验，证实了肿瘤相关巨噬细胞(TAM)上PI3Kγ分子可作为肿瘤免疫检查点，调控下游NF-κB、C/EBPβ等关键分子表达，维持TAM的M2表型，促进胃癌的增殖转移。同时，本研究还发现“益气健脾化瘀法”指导下的中药复方可抑制TAM上免疫检查点PI3Kγ的激活，增加NF-κB、减少C/EBPβ等下游关键蛋白的表达，从而促进TAM的表型从M2型向M1型转化，调节IL-10、TNF-α等炎症因子的释放，增强抗肿瘤免疫，抑制胃癌的进展。本研究明确了PI3Kγ对胃癌免疫微环境的影响和调控节点，及基于该机制下“益气健脾化瘀”法干预胃癌的具体环节。本课题有利开发胃癌治疗新靶点，诠释“益气健脾化瘀”治疗胃癌的科学性，为中医药治疗肿瘤提供了新思路。