Institute of Metabolism and Systems Research (IMSR), and Centre of Endocrinology, Diabetes and Metabolism (CEDAM), University of Birmingham, Birmingham, United Kingdom.
School of Biomedical Engineering & Imaging Sciences, King's College London, London, United Kingdom.
Clin Cancer Res. 2024 Apr 1;30(7):1352-1366. doi: 10.1158/1078-0432.CCR-23-2043.
Patients with aggressive thyroid cancer are frequently failed by the central therapy of ablative radioiodide (RAI) uptake, due to reduced plasma membrane (PM) localization of the sodium/iodide symporter (NIS). We aimed to understand how NIS is endocytosed away from the PM of human thyroid cancer cells, and whether this was druggable in vivo.
Informed by analysis of endocytic gene expression in patients with aggressive thyroid cancer, we used mutagenesis, NanoBiT interaction assays, cell surface biotinylation assays, RAI uptake, and NanoBRET to understand the mechanisms of NIS endocytosis in transformed cell lines and patient-derived human primary thyroid cells. Systemic drug responses were monitored via 99mTc pertechnetate gamma counting and gene expression in BALB/c mice.
We identified an acidic dipeptide within the NIS C-terminus that mediates binding to the σ2 subunit of the Adaptor Protein 2 (AP2) heterotetramer. We discovered that the FDA-approved drug chloroquine (CQ) modulates NIS accumulation at the PM in a functional manner that is AP2 dependent. In vivo, CQ treatment of BALB/c mice significantly enhanced thyroidal uptake of 99mTc pertechnetate in combination with the histone deacetylase (HDAC) inhibitor vorinostat/SAHA, accompanied by increased thyroidal NIS mRNA. Bioinformatic analyses validated the clinical relevance of AP2 genes with disease-free survival in RAI-treated DTC, enabling construction of an AP2 gene-related risk score classifier for predicting recurrence.
NIS internalization is specifically druggable in vivo. Our data, therefore, provide new translatable potential for improving RAI therapy using FDA-approved drugs in patients with aggressive thyroid cancer. See related commentary by Lechner and Brent, p. 1220.
由于钠/碘同向转运体（NIS）的质膜（PM）定位减少，侵袭性甲状腺癌患者常无法通过放射性碘（RAI）摄取的中心治疗。我们旨在了解 NIS 如何从人甲状腺癌细胞的 PM 被内吞，以及这种内吞在体内是否可被靶向。
根据侵袭性甲状腺癌患者内吞基因表达的分析，我们使用诱变、NanoBiT 相互作用测定、细胞表面生物素化测定、RAI 摄取和 NanoBRET 来理解转化细胞系和患者来源的人原代甲状腺细胞中 NIS 内吞的机制。通过 99mTc 高锝酸盐伽马计数和 BALB/c 小鼠中的基因表达监测系统药物反应。
我们在 NIS C 端发现一个酸性二肽，介导与衔接蛋白 2（AP2）异四聚体的 σ2 亚基结合。我们发现，FDA 批准的药物氯喹（CQ）以依赖 AP2 的方式在功能上调节 NIS 在 PM 处的积累。在体内，CQ 治疗 BALB/c 小鼠与组蛋白去乙酰化酶（HDAC）抑制剂伏立诺他/SAHA 联合显著增强甲状腺对 99mTc 高锝酸盐的摄取，同时甲状腺 NIS mRNA 增加。生物信息学分析验证了 AP2 基因与 RAI 治疗后 DTC 无病生存的临床相关性，从而构建了用于预测复发的 AP2 基因相关风险评分分类器。
NIS 内化在体内具有特异性的靶向性。因此，我们的数据为使用 FDA 批准的药物改善侵袭性甲状腺癌患者的 RAI 治疗提供了新的转化潜力。请参阅 Lechner 和 Brent 的相关评论，第 1220 页。
