Lin Chengzhong, Cao Wei, Ren Zhenhu, Tang Yu, Zhang Chunye, Yang Rong, Chen Yiming, Liu Zheqi, Peng Canbang, Wang Lizhen, Wang Xu, Ji Tong
Department of Oral and Maxillofacial-Head and Neck Oncology, Ninth People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, PR China.
Shanghai Key Laboratory of Stomatology and Shanghai Research Institute of Stomatology, Shanghai, PR China.
Oncoimmunology. 2017 Jul 20;6(11):e1353860. doi: 10.1080/2162402X.2017.1353860. eCollection 2017.
Programmed death ligand 1 (PD-L1) functions as a key immune inhibitory factor by binding with its receptor, programmed death 1 (PD-1), to induce immune cell dysfunction and escape of the immune system. However, the mechanisms of PD-L1 expression under growth factor stimulation are not well characterized. Here, we demonstrate a novel role for glial cell line-derived neurotrophic factor (GDNF) in upregulating PD-L1 expression in head and neck squamous cell carcinoma (HNSCC). The expression and correlation of PD-L1, GDNF and perineural invasion (PNI) status were evaluated by bioinformatics analysis of TCGA database and IHC assays from 145 HNSCC patients. PD-L1 expression was investigated by flow cytometry, Western blot and real-time PCR analyses in HNSCC cells after GNDF incubation. The cell signaling pathways activated by GDNF were analyzed with an antibody array and blocked by specific signaling inhibitors in cancer cell lines. PD-L1 expression was significantly higher in cancer cells that exhibited PNI in the HNSCC specimens, and elevated PD-L1 expression was significantly correlated with GDNF levels. GDNF not only enhanced cancer cell PNI in a co-culture of dorsal root ganglions and cancer cells but also had a potent role in inducing PD-L1 expression through the JAK2-STAT1 signaling pathway. Moreover, a JAK2 inhibitor attenuated GDNF-induced PD-L1 and enhanced tumor cell susceptibility to NK cell killing. Our findings provide clinically novel evidence that nerve-derived GDNF can increase PD-L1 levels in cancer cells around the perineural niche and that regulatory signaling is critical for cancer cell escape from immune surveillance in the nerve-cancer microenvironment.
程序性死亡配体1（PD-L1）通过与其受体程序性死亡1（PD-1）结合，作为关键的免疫抑制因子，诱导免疫细胞功能障碍和免疫系统逃逸。然而，生长因子刺激下PD-L1表达的机制尚未完全明确。在此，我们证明了胶质细胞源性神经营养因子（GDNF）在头颈部鳞状细胞癌（HNSCC）中上调PD-L1表达方面具有新的作用。通过对TCGA数据库的生物信息学分析以及对145例HNSCC患者的免疫组化检测，评估了PD-L1、GDNF的表达及其与神经周围浸润（PNI）状态的相关性。通过流式细胞术、蛋白质免疫印迹和实时定量PCR分析，研究了GDNF孵育后HNSCC细胞中PD-L1的表达情况。利用抗体芯片分析了GDNF激活的细胞信号通路，并在癌细胞系中用特异性信号抑制剂进行阻断。在HNSCC标本中，表现出PNI的癌细胞中PD-L1表达显著更高，且PD-L1表达升高与GDNF水平显著相关。GDNF不仅在背根神经节与癌细胞的共培养中增强了癌细胞的PNI，还通过JAK2-STAT1信号通路在诱导PD-L1表达方面发挥了重要作用。此外，JAK2抑制剂减弱了GDNF诱导的PD-L1表达，并增强了肿瘤细胞对NK细胞杀伤的敏感性。我们的研究结果提供了新的临床证据，即神经源性GDNF可增加神经周围微环境中癌细胞的PD-L1水平，且调节信号对于癌细胞在神经-肿瘤微环境中逃避免疫监视至关重要。
