非小细胞肺癌中PD-1+肿瘤细胞对PD-L1+髓源抑制细胞的募集及相互作用机制

Programmed cell death1 (PD-1) as one immune checkpoint, are widely expressed on immune cells. We have previously shown that PD-1 was also expressed on tumor cells from non-small cell lung cancer (NSCLC), played an important role in regulating the stemness of NSCLC and was correlated with the recruitment of PD-L1+ myeloid-derived suppressor cells (MDSC). However, there are few reports currently available regarding PD-1 in NSCLC. The interaction mechanism between NSCLC cells with PD-1 expression and PD-L1+MDSC remains to be further explored. We hypothesize that NSCLC cells with PD-1 expression and PD-L1+MDSC form a positive feedback loop, leading to tumorigenesis and progression. In order to prove our hypothesis, we will use NSCLC cell lines and nude mice model, by means of real time PCR, western blot, lentivirus transfection, RNA interference and so on, explore the mutual influence between PD-1 and PD-L1+MDSC, and confirm their interaction mechanism. PD-1 as a target to develop monoclonal antibody has been used in clinic, but its efficacy has yet to be improved. This study will lay the foundation for revealing NSCLC progression and provide new ideas for developing more specific therapeutic targets.

程序性细胞死亡因子1 (PD-1)身为免疫检查点的一员，广泛表达在免疫细胞表面。我们预实验结果提示PD-1同样表达在非小细胞肺癌（NSCLC）肿瘤细胞表面，在NSCLC干性调控中起重要作用，并与PD-L1+髓源抑制细胞（MDSC）募集相关。迄今PD-1在NSCLC的研究知之甚少，肿瘤细胞PD-1与PD-1+MDSC的相互影响机制还有待探讨。我们假设NSCLC中PD-1表达与PD-1+MDSC募集有正反馈作用。为了验证这一假说，我们将通过人NSCLC细胞系A549、H460和裸鼠模型，采用荧光定量PCR、蛋白印迹、慢病毒载体转染、RNA干扰等手段，从分子、细胞、组织以及动物整体水平等多方面探讨PD-1与PD-1+MDSC的相互影响，明确其相互作用机制。本研究将从PD-1和MDSC的新视点为揭示NSCLC进展奠定基础，从而为开发更具有针对性的治疗的治疗靶点提供新思路。

肺癌是发病率和死亡率位居全球首位的恶性肿瘤。程序性细胞死亡因子1 (PD-1)身为免疫检查点的一员，广泛表达在免疫细胞表面，抑制免疫活性细胞杀伤肿瘤的作用。我们通过免疫组化和免疫荧光定位发现PD-1同样表达在非小细胞肺癌肿瘤细胞表面，通过迁徙实验证实肿瘤细胞表面PD-1增加肿瘤细胞的迁徙能力。并通过流式细胞术检测非小细胞肺癌患者组织和外周血中MDSCs含量明显升高，并高表达PD-L1和CD39、CD73。通过体外细胞培养实验发现，MDSCs通过CD39/CD73抑制CD8+T细胞和NK细胞的增殖，并抑制NK细胞分泌IFN-g的能力。不仅如此，MDSCs通过CD39/CD73抑制肿瘤细胞的凋亡、促进其耐药性。动物实验提示CD39/CD73是MDSCs促进肿瘤生长的因素。采用免疫荧光定量和流式细胞术分析发现，CD39+CD73+MDSC分泌更多IL-10和TGF-b。TGF-b调控mTOR-HIF-1a信号通路上调MDSCs表达CD39/CD73。综上所述，这些发现表明PD-1作为抗肿瘤治疗的靶点具有更复杂的机制，提示CD39/CD73作为非小细胞肺癌的一个潜在治疗靶点。本项目的研究成果为寻找特异性靶向非小细胞肺癌治疗提供了一定的理论基础和数据支撑。