Wnt/β-catenin信号通路对非小细胞肺癌抗PD-1/PD-L1免疫治疗敏感性的影响及机制研究

The anti-PD-1/PD-L1 therapy, representing the current progress of immunotherapy, has made a big step in treating non-small cell lung cancer (NSCLC) and other cancers. However, its objective response rate is low, and the majority of patients fail to respond to anti-PD-1/PD-L1 therapy. It is of great significance to identify the participating factors and underlying mechanisms affecting the sensitivity of anti-PD-1/PD-L1 treatment. Previous studies have revealed that the infiltration and activation of CD8+ T lymphocytes in tumors is necessary for the success of anti-PD-1/PD-L1 therapy. In our preliminary studies, the number of tumor-infiltrating CD8+ T lymphocytes inversely correlated with β-catenin expression levels in NSCLC. Furthermore, our high-throughput screening showed that overexpression of Wnt/β-catenin signaling considerably upregulated expression of glycodelin, a potent immune-suppressive protein. Based on the above findings, we hypothesize that the Wnt/β-catenin signaling pathway may suppress the infiltration and activation of CD8+T lymphocytes by regulating glycodelin, which finally decreases the therapeutic efficacy of PD-1/PD-L1 checkpoint inhibitors. In this project, we will systemically examine whether Wnt/β-catenin signaling modulate the sensitivity of anti-PD-1/PD-L1 treatment, especially by regulating CD8+ T lymphocyte infiltration and activation mediated by glycodelin. Our study would help determine the factors influencing the sensitivity of anti-PD-1/PD-L1 therapy, provide fundamental evidence for improving the immunotherapy efficacy and promote more individualized and precise treatment for patients with NSCLC in the future.

以抗PD-1/PD-L1为代表的免疫治疗在晚期非小细胞肺癌等恶性肿瘤治疗中取得了较大进展，但总体有效率仍较低；阐明影响其敏感性的机制具有重要意义。研究表明，肿瘤局部CD8+ T细胞浸润与活化是该类药物有效的必要条件；前期研究发现，NSCLC病理组织中CD8+ T细胞浸润与Wnt通路中β-catenin表达成反比，高通量筛选表明Wnt通路过表达后Glycodelin这一免疫抑制分子的表达显著上调。因此我们推测，NSCLC中Wnt通路激活或过表达后可上调Glycodelin的表达，进而抑制肿瘤局部CD8+ T细胞浸润与活化，从而影响免疫治疗疗效。本课题拟系统研究Wnt/β-catenin通路对NSCLC免疫治疗疗效的影响，从Glycodelin调控CD8+ T细胞浸润与活化这一角度探讨其中的参与机制；研究将有助于明确影响免疫治疗疗效的参与因素，为其疗效改进和精准治疗方案的制定提供理论依据。

免疫治疗为非小细胞肺癌（non-small cell lung cancer，NSCLC）治疗提供了新的手段，在患者生存期改善等长期获益方面具有独特的优势；但是其总体有效率却较低，因此寻找调控抗PD-1/PD-L1药物敏感性的病理特征及阐明其参与机制将成为影响NSCLC免疫治疗疗效的重要因素。本项目主要研究了Wnt/β-catenin通路对NSCLC免疫治疗敏感性的影响，并通过体内外实验及NSCLC患者病理组织标本检测等方法研究其中的参与机制。我们分析了对抗PD-1/PD-L1（Programmed Death 1/ Programmed Cell Death-Ligand 1）免疫治疗敏感和不敏感的NSCLC患者中的基因表达情况，发现Wnt/β-catenin通路在对抗PD-1免疫治疗不敏感的患者中明显激活，并且CD8+T细胞浸润减少。前期研究发现，Wnt通路激活后 Glycodelin这一分子在转录水平的改变最为显著，因此我们通过激活或抑制NSCLC细胞中的Wnt/β-catenin通路后发现Glycodelin表达明显受到调控。我们使用过表达或敲减β-catenin的NSCLC细胞的条件培养基及重组Glycodelin蛋白处理CD8+T细胞，结果表明，敲减β-catenin表达的NSCLC细胞培养基可增强CD8+T细胞的活化、分泌细胞因子及杀伤肿瘤细胞的能力，而补充Glycodelin可部分逆转此现象。在患者病理组织标本中也发现了β-catenin表达与CD8+T细胞浸润的负相关性。我们的研究阐明了Wnt/β-catenin通路通过调控Glycodelin表达影响CD8+T细胞浸润与活性，从而抑制抗PD-1免疫治疗敏感性的机制，为NSCLC联合治疗策略的改进及敏感人群的筛选提供了更多的依据。