LAG-3在髓源性抑制细胞介导的口腔鳞癌免疫逃逸中的作用及机制研究

Immune escape has emerged as a hot topic in cancer research. With the support of National Nature Science Foundation, we investigate the role and molecular mechanism of myeloid-derived suppressor cells (MDSCs) in regulating oral squamous cell carcinoma (OSCC) angiogenesis. Our pilot study verify that novel immune checkpoint molecule lymphocyte activation gene-3 (LAG-3) inhibition significantly reduces OSCC infiltrating MDSCs. This project is anticipated to further investigate detailed molecular mechanism of LAG-3 regulation on MDSCs induced immune escape in OSCC. We hypothesize that LAG-3 may mediate the recruitment of MDSCs in tumor microenvironment, promote the proliferation, metabolism and immunosuppressive function of MDSCs; LAG-3+MDSCs may inhibit apoptosis of OSCC by LAG-3/MHC-II axis. This project includes four parts: firstly, we plan to quantify and correlate the expression of LAG-3 with tumor infiltrating MDSCs in mouse and human OSCC specimen; secondly, we intend to explore the role of LAG-3 on chemokines /chemokine receptors to recruit MDSCs by taking advantage of knockout mice OSCC model and medium throughput selection. Thirdly, we try to clarify the function of LAG-3+ MDSCs on immune suppression using Lab-on-chip. Finally, we will testify the mechanism of LAG-3+MDSCs inducing OSCC apoptosis through LAG-3/MHC-II axis in vitro and in vivo using co-culture system and patient derived xenograft model. Achievements of this project will contribute to a better understand of the mechanism of immune checkpoint molecule LAG-3 in regulating MDSCs and develop new potential strategies for OSCC treatment.

肿瘤免疫逃逸是当今癌症研究的热点。申请者在上一个面上项目《髓源抑制细胞在舌鳞癌血管生成中的作用》支持下，发现免疫检查点分子LAG-3可以调控口腔鳞癌中MDSCs。在前期研究基础上，本项目围绕“LAG-3在MDSCs介导口腔鳞癌免疫逃逸中的作用”这一科学问题，提出“LAG-3介导口腔鳞癌微环境对MDSCs的招募；LAG-3促进MDSCs增殖、代谢及免疫抑制功能；LAG-3/MHC-II信号轴抑制口腔鳞癌细胞凋亡”的科学假说。拟从以下四方面展开研究：①明确口腔鳞癌中 LAG-3与MDSCs的关系；②采用基因敲除小鼠模型及中通量芯片筛选LAG-3调控的趋化因子，明确 LAG-3调控MDSCs趋化的信号轴；③利用微流控芯片技术检测LAG-3+与LAG-3-MDSCs生物学功能的差异；④初步揭示LAG-3 / MHC-II轴抑制肿瘤细胞凋亡的机制。研究结果将为口腔鳞癌免疫治疗提供新的靶点及理论依据。

免疫检查点分子的异常激活，导致效应细胞失能，诱导肿瘤免疫逃逸，新型负性免疫检查点分子LAG-3在头颈鳞癌中的具体作用尚不明确。在本项目中，我们利用头颈鳞癌人类标本及转基因小鼠模型探索了LAG-3在头颈鳞癌中的表达水平及其与临床病理参数的相关性，并且进一步探索了LAG-3在髓源性抑制细胞（MDSCs）所介导的头颈鳞癌免疫逃逸中的作用及潜在机制。同时，我们也研究了与LAG-3密切相关的负性检查点分子CD73、Tim3、TIGIT等分子在头颈鳞癌中的作用及机制，并且进一步通过学科交叉应用新型纳米材料增强头颈鳞癌免疫治疗的响应率。在完成的实验中，我们可以得出以下结论：①LAG-3在头颈鳞癌中的表达与MDSC的含量呈密切正相关，LAG-3在头颈鳞癌中高表达提示不良预后，体内阻断LAG-3能显著抑制肿瘤生长并降低微环境中MDSC的数量；②靶向负性免疫检查点分子CD73，能够显著改善肿瘤微环境中T细胞的耗竭状态；③体内阻断TIGIT/CD155通路，可减缓肿瘤生长并解除MDSC的免疫抑制能力；④天然的MDCS膜源性仿生纳米材料能有效提高口腔鳞癌光热治疗的疗效；⑤应用硫化铅PbS量子点在近红外二区改性，能够在小鼠体内对MDSC进行高分辨成像；⑥应用谷胱甘肽/pH双应答纳米前药能够有效减少肿瘤微环境中MDSC的数量，增加肿瘤细胞免疫原性细胞死亡，增强PD-1免疫治疗的疗效；⑦在Pten/Tgfbr1 2cKO小鼠中，利用工程化肿瘤干细胞膜与血小板膜杂交细胞纳米材料能有效提高头颈鳞癌光热治疗的疗效。