NHC Key Laboratory of Carcinogenesis and Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China.
FuRong Laboratory, Changsha, Hunan, China.
J Immunother Cancer. 2024 Nov 14;12(11):e010091. doi: 10.1136/jitc-2024-010091.
Nasopharyngeal carcinoma (NPC) is a distinct subtype of head and neck cancer which is prevalent in south of China and southeastern of Asia. Consistent activation of interferon (IFN) signaling, and impairment of T cell mediated antitumor immunity is frequent in NPC. Forkhead box A1 (FOXA1) is one of the earliest discovered pioneer factors, which can open up compact chromatin structures to facilitate the binding of other proteins to chromatin.
By using RNA sequencing, it was discovered that FOXA1 suppresses the activation of the interferon signaling pathway and the expression of the related interferon-responsive genes in NPC cells. The effect of FOXA1 on programmed death-ligand 1 (PD-L1) expression in C666-1 and HK1 cells under conditions with or without IFN-γ was detected through quantitative PCR (qPCR), western blot, and flow cytometry. After co-culturing T cells with IFN-γ-treated NPC cells in vitro, apoptosis of CD8 T cells and the expression of cytotoxic cytokines were assessed by flow cytometry. The cytotoxic effects of T cells on tumor cells in nude mice were measured by tumorigenesis in nude mice and adoptive T cell therapy. The effects of IFN-γ on the expression and nuclear localization of STAT1, as well as the colocalization of FOXA1 with STAT1 were detected by immunofluorescence, qPCR, western blot, and co-immunoprecipitation experiments.
In this study, we reported that loss of FOXA1, a pioneer factor downregulated in NPC, results in activation of IFN signaling in NPC cells. Repression of FOXA1 facilitates IFN-γ induced PD-L1 expression, whereas overexpression of FOXA1 exerts the opposite effect. Mechanistically, FOXA1 interacts with STAT1 and inhibits IRF1 expression and binding to PD-L1 promoter on IFN-γ treatment. Co-culture with FOXA1-silenced NPC cells promotes apoptosis of in vitro activated tumor-specific CD8T cells and reduces the expression of cytotoxic effector molecules. Furthermore, overexpression of FOXA1 increases the therapeutic efficacy of PD-L1 antibody (atezolizumab) against NPC in nude mice receiving adoptive T-cell therapy.
We demonstrated that FOXA1 prevents tumor immune evasion by inhibiting IFN-γ induced PD-L1 expression in NPC cells. Our research findings provide new insights into the immunotherapeutic biomarkers and targets for NPC, which is important for the clinical application of programmed cell death protein-1/PD-L1 antibodies in NPC.
鼻咽癌（NPC）是一种独特的头颈部癌症亚型，在中国南方和东南亚地区较为常见。干扰素（IFN）信号的持续激活以及 T 细胞介导的抗肿瘤免疫功能受损在 NPC 中很常见。叉头框蛋白 A1（FOXA1）是最早发现的先驱因子之一，它可以打开紧密的染色质结构，促进其他蛋白质与染色质的结合。
通过 RNA 测序，发现在 NPC 细胞中，FOXA1 抑制干扰素信号通路的激活和相关干扰素反应基因的表达。通过定量 PCR（qPCR）、western blot 和流式细胞术检测 FOXA1 在 C666-1 和 HK1 细胞中对 PD-L1 表达的影响，在有或没有 IFN-γ的情况下。体外共培养 IFN-γ处理的 NPC 细胞与 T 细胞后，通过流式细胞术评估 CD8 T 细胞的凋亡和细胞毒性细胞因子的表达。通过裸鼠肿瘤生成和过继性 T 细胞治疗测量裸鼠中 T 细胞对肿瘤细胞的细胞毒性作用。通过免疫荧光、qPCR、western blot 和 co-immunoprecipitation 实验检测 IFN-γ对 STAT1 的表达和核定位以及 FOXA1 与 STAT1 的共定位的影响。
在这项研究中，我们报告了 NPC 中下调的先驱因子 FOXA1 的缺失导致 NPC 细胞中 IFN 信号的激活。FOXA1 的抑制促进了 IFN-γ诱导的 PD-L1 表达，而 FOXA1 的过表达则产生相反的效果。在机制上，FOXA1 与 STAT1 相互作用，抑制 IRF1 的表达，并在 IFN-γ处理时与 PD-L1 启动子结合。与沉默 FOXA1 的 NPC 细胞共培养可促进体外激活的肿瘤特异性 CD8 T 细胞的凋亡，并降低细胞毒性效应分子的表达。此外，过表达 FOXA1 增加了接受过继性 T 细胞治疗的裸鼠中 PD-L1 抗体（阿特珠单抗）对 NPC 的治疗效果。
我们证明了 FOXA1 通过抑制 NPC 细胞中 IFN-γ诱导的 PD-L1 表达来防止肿瘤免疫逃逸。我们的研究结果为 NPC 的免疫治疗生物标志物和靶点提供了新的见解，这对于程序性细胞死亡蛋白-1/PD-L1 抗体在 NPC 中的临床应用很重要。
