miR-106a/RARB/MAPK信号轴参与PD-L1调控乳头状甲状腺癌失分化机制研究

Metastatic radioiodine refractory papillary thyroid cancer (RR-PTC) is the major obstacle in the management of papillary thyroid cancer. Recent studies revealed that immune checkpoint PD-L1 was closely related to tumor progression and drug resistance. Based on our previous reports and preliminary experimental results, we suppose that miR-106a/RARB/MAPK pathway may play a vital role inthe regulation of PTC dedifferentiation via regulating PD-L1. To establish the central role of miR-106a/RARB/MAPK/PD-L1/NIS in the regulation of PTC dedifferentiation, we will overexpress/silence PD-L1/miR-106a in PTC cell lines and perform a series of experiments including qRT-PCR, Western-blot, immunofluorescence, flow cytometry, radioiodine uptake and micro-PET/CT in vitro and in vivo to explore the impact of PD-L1/ miR-106a on cell cycle distribution, apoptosis, migration and dedifferentiation. Our current research will provide insights into the pivotal role of miR-106a/RARB/MAPK/PD-L1/NIS pathway in regulating differentiation status of PTC and explore novel therapeutic target for radioiodine refractory papillary thyroid cancer.

转移灶失分化是131I治疗PTC面临的主要临床问题。研究发现免疫学靶点PD-L1与肿瘤细胞的恶性程度及耐药性密切相关。本研究基于前一个国家自然基金发现及前期实验结果提出科学假设：miR-106a/RARB/MAPK信号轴参与PD-L1调控PTC失分化机制。本研究采用干扰和过表达miR-106a、PD-L1的甲状腺癌细胞株，通过免疫组化、qRT-PCR、Western-blot、碘摄取实验及micro-PET/CT等实验方法，体外实验检测细胞凋亡、增殖、周期及侵袭性，RARB、MAPK信号通路、PD-L1、NIS等相关基因和蛋白表达水平，及碘和葡萄糖代谢变化，并通过体内实验进一步验证；最终阐明miR-106a/RARB/MAPK信号轴参与PD-L1调控PTC失分化机制。本研究为PD-L1抑制剂应用于治疗PTC失分化提供理论依据，为分子靶向药物联合PD-L1抑制剂治疗PTC失分化奠定理论基础。

转移灶失分化是目前碘-131治疗PTC主要障碍；本课题组多篇临床研究证实：转移灶不摄取碘-131是影响DTC预后的独立因子,这为开展后续基础研究顺利进行奠定了前期临床基础。本课题组首先从炎症和免疫的关系为切入点探索DTC失分化机制，结合综述研究进展，通过免疫组化分析，本课题组发现IL-6、IL-12A 和 PD-L1 在甲状腺癌组织中高表达;单因素及多因素分析显示，IL-12A表达是甲状腺癌 DFS 的独立预测因素；IL-6 和 PD-L1 与原发灶数目、颈部淋巴结转移、远处转移、危险度分层等DTC的恶性特征明显相关。在此基础上，本课题组通过TPC-1 和 BCPAP细胞培养,干扰 RNA 技术、蛋白质免疫印迹、实时荧光定量聚合酶链反应、流式细胞检测和染色质免疫共沉淀等技术，证明IL-6通过激活 MAPK-ERK 和 MAPK-JNK 、JAK/STAT3信号通路，导致转移因子c-Jun和p-Stat3表达降低；一方面可促进 PD-L1 的表达升高，为白介素抑制剂协同抗PD-L1药物治疗PTC提供了新的思路。另一方面使转录因子TTF-1和PAX-8的表达降低，最终导致NIS的表达下调及PTC碘-131摄取功能降低；这为IL-6抑制剂治疗PTC失分化奠定了理论基础。