甘草查尔酮 A 抑制肺癌细胞中干扰素-γ诱导的程序性死亡配体 1。
Licochalcone A inhibits interferon-gamma-induced programmed death-ligand 1 in lung cancer cells.
机构信息
State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China.
出版信息
Phytomedicine. 2021 Jan;80:153394. doi: 10.1016/j.phymed.2020.153394. Epub 2020 Oct 22.
BACKGROUND
Programmed death-ligand 1 (PD-L1), which can be induced by interferon-gamma (IFN-γ) in the tumor microenvironment, is a critical immune checkpoint in cancer immunotherapy. Natural products which reduce IFN-γ-induced PD-L1 might be exert immunotherapy effect. Licochalcone A (LCA), a natural compound derived from the root of Glycyrrhiza inflata Batalin. (Fabaceae), was found to interfere IFN-γ-induced PD-L1.
PURPOSE
The aim of this study is to further clarify the effect and the mechanism of LCA on inhibiting IFN-γ-induced PD-L1 in lung cancer cells.
METHODS
The expression levels of PD-L1 were evaluated by flow cytometry, western blot and qRT-PCR. Click-iT protein synthesis assay and luciferase assay were used to identify the effect of LCA on protein synthesis. Jurkat T cell proliferation and apoptosis in the co-culture system were detected by flow cytometry. Flow cytometry was also applied to evaluate reactive oxygen species (ROS) generation.
RESULTS
LCA downregulated IFN-γ-induced PD-L1 protein expression and membrane localization in human lung cancer cells, regardless of inhibiting PD-L1 mRNA level or promoting its protein degradation. LCA decreased apoptosis and proliferative inhibition of Jurkat T cells caused by IFN-γ-induced PD-L1-expressing in A549 cells in the co-culture system. Strikingly, LCA was verified as a protein synthesis inhibitor, which reduced both cap-dependent and -independent translation. LCA inhibited PD-L1 translation, likely due to inhibition of 4EBP1 phosphorylation (Ser 65) and activation of PERK-eIF2α pathway. Furthermore, LCA induced ROS generation in a time-dependent manner in lung cancer cells. N-acetyl-L-cysteine (NAC) not only revered ROS generation triggered by LCA but also restored IFN-γ-induced expression of PD-L1. Both the inhibition of 4EBP1 phosphorylation (Ser 65) and activation of PERK-eIF2α axis triggered by LCA was restored by co-treatment with NAC.
CONCLUSION
LCA abrogated IFN-γ-induced PD-L1 expression via ROS generation to abolish the protein translation, indicating that LCA has the potential to be applied in cancer immunotherapy.
背景
程序性死亡配体 1（PD-L1）可在肿瘤微环境中由干扰素-γ（IFN-γ）诱导，是癌症免疫治疗中的一个关键免疫检查点。降低 IFN-γ 诱导的 PD-L1 的天然产物可能具有免疫治疗作用。甘草查尔酮 A（LCA）是从甘草根中提取的一种天然化合物，发现其能干扰 IFN-γ 诱导的 PD-L1。
目的
本研究旨在进一步阐明 LCA 抑制肺癌细胞中 IFN-γ 诱导的 PD-L1 的作用和机制。
方法
采用流式细胞术、Western blot 和 qRT-PCR 评估 PD-L1 的表达水平。Click-iT 蛋白合成测定法和荧光素酶测定法用于鉴定 LCA 对蛋白合成的影响。通过流式细胞术检测共培养系统中 Jurkat T 细胞的增殖和凋亡。流式细胞术还用于评估活性氧（ROS）的产生。
结果
LCA 下调了人肺癌细胞中 IFN-γ 诱导的 PD-L1 蛋白表达和膜定位，无论是否抑制 PD-L1 mRNA 水平或促进其蛋白降解。LCA 降低了共培养系统中 IFN-γ 诱导 A549 细胞表达 PD-L1 导致的 Jurkat T 细胞凋亡和增殖抑制。值得注意的是，LCA 被证实为一种蛋白合成抑制剂，可减少帽依赖性和非依赖性翻译。LCA 抑制 PD-L1 翻译，可能是由于抑制 4EBP1 磷酸化（Ser65）和激活 PERK-eIF2α 途径。此外，LCA 以时间依赖性方式在肺癌细胞中诱导 ROS 产生。N-乙酰-L-半胱氨酸（NAC）不仅逆转了 LCA 触发的 ROS 产生，还恢复了 IFN-γ 诱导的 PD-L1 表达。LCA 诱导的 4EBP1 磷酸化（Ser65）抑制和 PERK-eIF2α 轴激活均被 NAC 共同处理所恢复。
结论
LCA 通过 ROS 产生来消除蛋白质翻译，从而阻断 IFN-γ 诱导的 PD-L1 表达，表明 LCA 有可能应用于癌症免疫治疗。
Zotero 插件