Granulocyte-macrophage colony stimulating factor (GM-CSF) is a cytokine that is used as an immunopotentiator for anti-tumor therapies in recent years. We found that some of the extranodal natural killer/T cell lymphoma (ENKTL) patients with the treatment of hGM-CSF rapidly experienced disease progression, but the underlying mechanisms remain to be elucidated. Here, we aimed to explore the mechanisms of disease progression triggered by GM-CSF in ENKTL. The mouse models bearing EL4 cell tumors were established to investigate the effects of GM-CSF on tumor growth and T cell infiltration and function. Human ENKTL cell lines including NK-YS, SNK-6, and SNT-8 were used to explore the expression of programmed death-ligand 1 (PD-L1) induced by GM-CSF. To further study the mechanisms of disease progression of ENKTL in detail, the mutations and gene expression profile were examined by next-generation sequence (NGS) in the ENKTL patient’s tumor tissue samples. The mouse-bearing EL4 cell tumor exhibited a faster tumor growth rate and poorer survival in the treatment with GM-CSF alone than in treatment with IgG or the combination of GM-CSF and PD-1 antibody. The PD-L1 expression at mRNA and protein levels was significantly increased in ENKTL cells treated with GM-CSF. STAT5A high-frequency mutation including p.R131G, p.D475N, p.F706fs, p.V707E, and p.S710F was found in 12 ENKTL cases with baseline tissue samples. Importantly, STAT5A-V706fs mutation tumor cells exhibited increased activation of STAT5A pathway and PD-L1 overexpression in the presence of GM-CSF. These findings demonstrate that GM-CSF potentially triggers the loss of tumor immune surveillance in ENKTL patients and promotes disease progression, which is associated with STAT5 mutations and JAK2 hyperphosphorylation and then upregulates the expression of PD-L1. These may provide new concepts for GM-CSF application and new strategies for the treatment of ENKTL.

中文翻译：

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GM-CSF通过上调结外自然杀伤/T细胞淋巴瘤中的PD-L1表达介导免疫逃逸

粒细胞-巨噬细胞集落刺激因子（GM-CSF）是一种细胞因子，近年来被用作抗肿瘤治疗的免疫增强剂。我们发现一些接受 hGM-CSF 治疗的结外自然杀伤/T 细胞淋巴瘤 (ENKTL) 患者疾病进展迅速，但其潜在机制仍有待阐明。在这里，我们旨在探索由 GM-CSF 在 ENKTL 中引发的疾病进展机制。建立携带EL4细胞肿瘤的小鼠模型，研究GM-CSF对肿瘤生长和T细胞浸润和功能的影响。包括NK-YS、SNK-6和SNT-8在内的人ENKTL细胞系用于探索GM-CSF诱导的程序性死亡配体1（PD-L1）的表达。为了进一步详细研究ENKTL的疾病进展机制，通过下一代序列 (NGS) 在 ENKTL 患者的肿瘤组织样本中检查突变和基因表达谱。与 IgG 或 GM-CSF 和 PD-1 抗体联合治疗相比，单独使用 GM-CSF 治疗的小鼠 EL4 细胞肿瘤表现出更快的肿瘤生长速度和较差的存活率。在用 GM-CSF 处理的 ENKTL 细胞中，mRNA 和蛋白质水平的 PD-L1 表达显着增加。在基线组织样本的 12 例 ENKTL 病例中发现了包括 p.R131G、p.D475N、p.F706fs、p.V707E 和 p.S710F 在内的 STAT5A 高频突变。重要的是，在 GM-CSF 存在下，STAT5A-V706fs 突变肿瘤细胞表现出 STAT5A 通路激活增加和 PD-L1 过表达。这些发现表明，GM-CSF 可能会引发 ENKTL 患者肿瘤免疫监视的丧失并促进疾病进展，这与 STAT5 突变和 JAK2 过度磷酸化有关，然后上调 PD-L1 的表达。这些可能为 GM-CSF 应用提供新概念和治疗 ENKTL 的新策略。