Department of Thyroid and Breast Surgery, Tianjin Key Laboratory of General Surgery in Construction, Tianjin Union Medical Center, Tianjin, 300121, China.
Department of Thyroid and Neck Cancer, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Tianjin, 300060, China.
Cell Death Differ. 2023 Oct;30(10):2265-2279. doi: 10.1038/s41418-023-01217-x. Epub 2023 Aug 30.
The treatment options for advanced papillary thyroid cancer (PTC) and anaplastic thyroid cancer (ATC) refractory to standard therapies are limited. Although anti-PD-1 therapy has a manageable safety profile and has been effective in a small percentage of patients with advanced PTC and refractory ATC, the majority of the patients either do not respond or develop resistance to anti-PD-1 therapy. N6-methyladenosine (m6A) modification is a critical determinant of the complexity of the tumor microenvironment (TME). However, it is unclear whether and how m6A modification in tumor cells shapes the immune landscape of PTC and ATC. In this study, we performed bulk and single cell RNA sequencing analysis of PTC and ATC tissues, and found that low METTL3 expression not only correlated to poor response to immune checkpoint blockade (ICB) but was also associated with increased TNF family-related ligand-receptor interactions in the immunosuppressive Tregs and exhausted T cells. Furthermore, overexpression of METTL3 in PTC and ATC cells enhanced the efficacy of anti-PD-1 therapy in a peripheral blood mononuclear cell humanized NCG (huPBMC-NCG) mouse model. Mechanistically, M2 macrophage-derived extracellular vesicles (M2 EVs) inhibited METTL3 expression in PTC and ATC cells via miR-21-5p. Downregulation of METTL3 promoted demethylation of CD70 mRNA, which prevented YTHDF2-mediated degradation of the transcripts. The stabilization of CD70 mRNA, and the subsequent upregulation in CD70 protein levels increased the abundance of the immunosuppressive Tregs and terminally exhausted T cells, thereby inducing resistance to anti-PD-1 therapy. Furthermore, blocking CD70 using cusatuzumab, a high-affinity monoclonal antibody, reversed the anti-PD-1 therapy resistance induced by M2 EVs in vivo. Finally, we demonstrated that METTL3 expression negatively correlated with CD70 expression and M2 macrophages and Tregs infiltration in PTC and ATC tissues. Our findings provide new insights into developing novel therapies for advanced PTC and ATC.
晚期甲状腺乳头状癌（PTC）和间变性甲状腺癌（ATC）对标准治疗耐药的治疗选择有限。虽然抗 PD-1 治疗具有可管理的安全性，并且在一小部分晚期 PTC 和耐药 ATC 患者中有效，但大多数患者要么没有反应，要么对抗 PD-1 治疗产生耐药性。N6-甲基腺苷（m6A）修饰是肿瘤微环境（TME）复杂性的关键决定因素。然而，尚不清楚肿瘤细胞中的 m6A 修饰是否以及如何塑造 PTC 和 ATC 的免疫景观。在这项研究中，我们对 PTC 和 ATC 组织进行了批量和单细胞 RNA 测序分析，发现低 METTL3 表达不仅与对免疫检查点阻断（ICB）的反应不佳相关，而且还与免疫抑制性 Tregs 和耗竭 T 细胞中 TNF 家族相关配体-受体相互作用增加相关。此外，在 PTC 和 ATC 细胞中过表达 METTL3 增强了抗 PD-1 治疗在人外周血单核细胞 NCG（huPBMC-NCG）小鼠模型中的疗效。在机制上，M2 巨噬细胞衍生的细胞外囊泡（M2 EVs）通过 miR-21-5p 抑制 PTC 和 ATC 细胞中的 METTL3 表达。METTL3 的下调促进了 CD70 mRNA 的去甲基化，从而防止了 YTHDF2 对转录本的降解。CD70 mRNA 的稳定，以及随后 CD70 蛋白水平的上调，增加了免疫抑制性 Tregs 和终末期耗竭 T 细胞的丰度，从而诱导对抗 PD-1 治疗的耐药性。此外，使用 cusatuzumab，一种高亲和力的单克隆抗体阻断 CD70，可在体内逆转 M2 EV 诱导的抗 PD-1 治疗耐药性。最后，我们证明 METTL3 表达与 PTC 和 ATC 组织中的 CD70 表达以及 M2 巨噬细胞和 Tregs 浸润呈负相关。我们的研究结果为开发晚期 PTC 和 ATC 的新疗法提供了新的见解。
