KAP1 通过保护 RNA mA 阅读蛋白 YTHDC1 的降解来稳定 MYCN mRNA 并促进神经母细胞瘤的致瘤性。
KAP1 stabilizes MYCN mRNA and promotes neuroblastoma tumorigenicity by protecting the RNA mA reader YTHDC1 protein degradation.
机构信息
Pediatric Translational Medicine Institute, Department of Hematology & Oncology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, National Health Committee Key Laboratory of Pediatric Hematology & Oncology, Shanghai, 200127, China.
State Key Laboratory of Systems Medicine for Cancer, Renji-Med X Clinical Stem Cell Research Center, Ren Ji Hospital, Shanghai Cancer Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China.
出版信息
J Exp Clin Cancer Res. 2024 May 14;43(1):141. doi: 10.1186/s13046-024-03040-9.
BACKGROUND
Neuroblastoma (NB) patients with amplified MYCN often face a grim prognosis and are resistant to existing therapies, yet MYCN protein is considered undruggable. KAP1 (also named TRIM28) plays a crucial role in multiple biological activities. This study aimed to investigate the relationship between KAP1 and MYCN in NB.
METHODS
Transcriptome analyses and luciferase reporter assay identified that KAP1 was a downstream target of MYCN. The effects of KAP1 on cancer cell proliferation and colony formation were explored using the loss-of-function assays in vitro and in vivo. RNA stability detection was used to examine the influence of KAP1 on MYCN expression. The mechanisms of KAP1 to maintain MYCN mRNA stabilization were mainly investigated by mass spectrum, immunoprecipitation, RIP-qPCR, and western blotting. In addition, a xenograft mouse model was used to reveal the antitumor effect of STM2457 on NB.
RESULTS
Here we identified KAP1 as a critical regulator of MYCN mRNA stability by protecting the RNA N-methyladenosine (mA) reader YTHDC1 protein degradation. KAP1 was highly expressed in clinical MYCN-amplified NB and was upregulated by MYCN. Reciprocally, KAP1 knockdown reduced MYCN mRNA stability and inhibited MYCN-amplified NB progression. Mechanistically, KAP1 regulated the stability of MYCN mRNA in an mA-dependent manner. KAP1 formed a complex with YTHDC1 and RNA mA writer METTL3 to regulate mA-modified MYCN mRNA stability. KAP1 depletion decreased YTHDC1 protein stability and promoted MYCN mRNA degradation. Inhibiting MYCN mRNA mA modification synergized with chemotherapy to restrain tumor progression in MYCN-amplified NB.
CONCLUSIONS
Our research demonstrates that KAP1, transcriptionally activated by MYCN, forms a complex with YTHDC1 and METTL3, which in turn maintain the stabilization of MYCN mRNA in an mA-dependent manner. Targeting mA modification by STM2457, a small-molecule inhibitor of METTL3, could downregulate MYCN expression and attenuate tumor proliferation. This finding provides a new alternative putative therapeutic strategy for MYCN-amplified NB.
背景
神经母细胞瘤（NB）患者的 MYCN 扩增往往预后不佳，对现有治疗方法产生耐药性，但 MYCN 蛋白被认为不可成药。KAP1（也称为 TRIM28）在多种生物学活动中发挥着关键作用。本研究旨在探讨 KAP1 与 NB 中 MYCN 的关系。
方法
转录组分析和荧光素酶报告基因实验鉴定 KAP1 是 MYCN 的下游靶点。体外和体内的功能丧失实验研究了 KAP1 对癌细胞增殖和集落形成的影响。通过 RNA 稳定性检测来研究 KAP1 对 MYCN 表达的影响。通过质谱分析、免疫沉淀、RIP-qPCR 和 Western blot 等方法主要研究了 KAP1 维持 MYCN mRNA 稳定性的机制。此外，还使用异种移植小鼠模型来揭示 STM2457 对 NB 的抗肿瘤作用。
结果
本研究通过保护 RNA N6-甲基腺苷（m6A）阅读器 YTHDC1 蛋白降解，鉴定出 KAP1 是 MYCN mRNA 稳定性的关键调节因子。KAP1 在临床 MYCN 扩增型 NB 中高表达，并受 MYCN 上调。相反，KAP1 敲低降低了 MYCN mRNA 的稳定性，抑制了 MYCN 扩增型 NB 的进展。在机制上，KAP1 通过 m6A 依赖性方式调节 MYCN mRNA 的稳定性。KAP1 与 YTHDC1 和 RNA m6A 书写器 METTL3 形成复合物，调节 m6A 修饰的 MYCN mRNA 稳定性。KAP1 耗尽会降低 YTHDC1 蛋白稳定性并促进 MYCN mRNA 降解。抑制 MYCN mRNA m6A 修饰与化疗协同作用，可抑制 MYCN 扩增型 NB 的肿瘤进展。
结论
本研究表明，转录激活的 KAP1 与 YTHDC1 和 METTL3 形成复合物，进而以 m6A 依赖性方式维持 MYCN mRNA 的稳定性。通过小分子抑制剂 STM2457 靶向 mA 修饰，可以下调 MYCN 表达并减弱肿瘤增殖。这一发现为 MYCN 扩增型 NB 提供了一种新的潜在治疗策略。
Zotero 插件