[摘 要] 目的：探讨lncRNA DLEU2通过EZH2/H3K27me3途径调控IKKα介导甲状腺癌（TC）放射性碘抵抗的作用机制。方法：利用TCGA数据库分析TC中DLEU2的表达及其与EZH2的相关性。构建放射性碘抵抗的TPC-1细胞（RR-TPC-1细胞）模型及裸鼠移植瘤模型，通过敲低或过表达DLEU2（si-DLEU2/OE-DLEU2）、抑制EZH2（UNC1999）、过表达IKKα（OE-IKKα）进行干预，采用qPCR、WB、RIP、ChIP、CCK-8、流式细胞术、TUNEL染色及体内成瘤实验检测基因与蛋白表达、表观修饰、细胞增殖、凋亡及肿瘤生长。结果：TCGA分析显示，DLEU2在TC组织中显著上调（P < 0.001），与患者不良预后相关（P = 0.0084），且与EZH2表达呈正相关（r = 0.390, P < 0.001）；RIP证实EZH2与DLEU2存在相互作用/结合（P < 0.05）。体外实验表明，敲低DLEU2可显著下调RR-TPC-1细胞中EZH2、IKKα表达及H3K27me3修饰水平，抑制NF-κB通路活化（P < 0.05或P < 0.01），抑制细胞增殖、促进凋亡（均P < 0.05）。联合敲低DLEU2与抑制EZH2进一步增强上述效应，而过表达IKKα则可部分逆转上述效应（P < 0.05或P < 0.01）。体内实验进一步证实，敲低DLEU2联合抑制EZH2可显著抑制移植瘤生长，增加肿瘤细胞凋亡（均P < 0.01）；IKKα过表达则部分逆转上述抗肿瘤效应（P < 0.05或P < 0.01）。结论：lncRNA DLEU2通过招募EZH2催化H3K27me3修饰，间接激活IKKα/NF-κB信号并形成正反馈环路，介导TPC-1细胞131I抵抗。

[Abstract] Objective: To investigate the mechanism by which lncRNA DLEU2 regulates IKKα-mediated radioiodine resistance in thyroid carcinoma (TC) through the EZH2/H3K27me3 axis. Methods: DLEU2 expression and its association with EZH2 in TC were analyzed using the TCGA database. Radioiodine-resistant TPC-1 cell (RR-TPC-1 cell) model and the nude mouse xenograft models were established. Following interventions including DLEU2 knockdown or overexpression (si-DLEU2/OE-DLEU2), EZH2 inhibition (UNC1999), and IKKα overexpression (OE-IKKα), gene and protein expression, histone modifications, cell proliferation, apoptosis, and tumorigenicity were detected by qPCR, Western blot, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP), CCK-8 assay, flow cytometry, TUNEL staining, and xenograft tumor growth assay. Results: TCGA analysis revealed significant upregulation of DLEU2 in TC (P < 0.001), which was associated with poor prognosis (P = 0.0084) and was positively correlated with EZH2 expression (Pearson r = 0.390, P < 0.001). RIP assay revealed an interaction between EZH2 and DLEU2 (P < 0.05). In vitro experiments indicated that DLEU2 knockdown in RR-TPC-1 cells markedly reduced EZH2 and IKKα expression as well as H3K27me3 levels, inhibited NF-κB pathway activation (P < 0.05 or P < 0.01), suppressed cell proliferation and promoted cell apoptosis (all P < 0.05). DLEU2 knockdown combined with EZH2 inhibition further enhanced these effects while IKKα overexpression partially reversed these effects (P < 0.05 or P < 0.01). In vivo experiments further demonstrated that DLEU2 knockdown combined with EZH2 inhibition significantly inhibited xenograft growth and promoted tumor cell apoptosis (all P < 0.01), while IKKα overexpression partially reversed the above-mentioned anti-tumor effects (P < 0.05 or P < 0.01). Conclusion: lncRNA DLEU2, through recruiting EZH2 to catalyze H3K27me3 modification, indirectly activates the IKKα/NF-κB signaling and establishes a positive feedback loop, which mediates 131I resistance in TPC-1 cells.

国家自然科学基金（8186070093）