PO.ET03.05 · 实验与分子治疗
由circSOD2编码的一种新型149氨基酸蛋白抑制铁死亡并促进膀胱癌顺铂耐药
A novel 149-amino acid protein encoded by circSOD2 inhibits ferroptosis and promotes cisplatin resistance in bladder cancer
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摘要 Abstract
中文摘要
环状RNA（circRNA）在膀胱癌（BCa）的肿瘤发生、转移和化疗耐药中发挥关键作用，但其在顺铂诱导的铁死亡中的功能性参与仍不甚明确。在此，我们通过RNA测序鉴定circSOD2为顺铂耐药BCa细胞系和临床标本中显著上调的circRNA。功能实验证明，circSOD2过表达在体外（CCK-8、集落形成和铁死亡检测实验）和体内（异种移植小鼠模型）增强了BCa细胞增殖和顺铂耐药。机制上，核糖体图谱分析和Western blot分析证实了circSOD2的蛋白编码潜能，其翻译产生一种新型149氨基酸肽（SOD2-149aa）。免疫共沉淀（Co-IP）和谷胱甘肽S-转移酶（GST）pull-down实验验证SOD2-149aa直接结合三基序蛋白26（TRIM26，一种泛素E3连接酶）的RING结构域。这种相互作用激活TRIM26介导的谷胱甘肽过氧化物酶4（GPX4，一种关键的抗铁死亡酶）在赖氨酸残基148处的K63连接多聚泛素化，从而阻止GPX4的蛋白酶体降解并增强其蛋白稳定性。稳定化的GPX4有效清除脂质活性氧（ROS）并减少铁依赖性脂质过氧化，最终减轻顺铂诱导的铁死亡并赋予BCa顺铂耐药。相反，circSOD2沉默或SOD2-149aa敲除废除了TRIM26-GPX4相互作用，削弱了GPX4稳定性，并恢复了BCa细胞对顺铂的敏感性。总之，我们的发现揭示了一种新型circRNA编码肽，其通过TRIM26-GPX4轴调控铁死亡和化疗耐药，凸显circSOD2/SOD2-149aa作为克服BCa顺铂耐药的有前景的预后生物标志物和治疗靶点。
查看英文原文 English abstract
Circular RNAs (circRNAs) play pivotal roles in bladder cancer (BCa) tumorigenesis, metastasis, and chemoresistance, but their functional involvement in cisplatin-induced ferroptosis remains poorly defined. Herein, we identified circSOD2 as a significantly upregulated circRNA in cisplatin-resistant BCa cell lines and clinical specimens via RNA sequencing. Functional assays demonstrated that circSOD2 overexpression enhanced BCa cell proliferation and cisplatin resistance in vitro (CCK-8, colony formation, and ferroptosis detection assays) and in vivo (xenograft mouse models). Mechanistically, ribosome profiling and Western blot analyses confirmed the protein-coding potential of circSOD2, which translates into a novel 149-amino acid peptide (SOD2-149aa). Co-immunoprecipitation (Co-IP) and glutathione S-transferase (GST) pull-down assays verified that SOD2-149aa directly binds to the RING domain of tripartite motif 26 (TRIM26), a ubiquitin E3 ligase. This interaction activates TRIM26-mediated K63-linked polyubiquitination of glutathione peroxidase 4 (GPX4) - a key anti-ferroptotic enzyme - at lysine residue 148, thereby preventing GPX4 proteasomal degradation and enhancing its protein stability. Stabilized GPX4 efficiently scavenges lipid reactive oxygen species (ROS) and reduces iron-dependent lipid peroxidation, ultimately mitigating cisplatin-induced ferroptosis and conferring cisplatin resistance in BCa. Conversely, circSOD2 silencing or SOD2-149aa knockout abrogated TRIM26-GPX4 interaction, diminished GPX4 stability, and restored BCa cell sensitivity to cisplatin. Collectively, our findings uncover a novel circRNA-encoded peptide that regulates ferroptosis and chemoresistance via the TRIM26-GPX4 axis, highlighting circSOD2/SOD2-149aa as a promising prognostic biomarker and therapeutic target for overcoming cisplatin resistance in BCa.
利益披露 Disclosure
S. Guo, None..
Z. Lv, None..
N. Wang, None..
X. Jiang, None.