环状 RNA circRNF13 通过 SUMO2 抑制鼻咽癌的增殖和转移。

BACKGROUND: Circular RNAs (circRNAs) are widely expressed in human cells and are closely associated with cancer development. However, they have rarely been investigated in the context of nasopharyngeal carcinoma (NPC). METHODS: We screened a new circRNA, circRNF13, in NPC cells using next-generation sequencing of mRNA. Reverse transcription polymerase chain reaction and RNA fluorescence in situ hybridization were used to detect circRNF13 expression in 12 non-tumor nasopharyngeal epithelial (NPE) tissues and 36 NPC samples. Cell proliferation was detected using MTT and flow cytometry assays, and colony formation capability was detected using colony formation assays. Cell migration and invasion were analyzed using wound-healing and Transwell assays, respectively. Cell glycolysis was analyzed using the Seahorse glycolytic stress test. Glucose transporter type 1 (GLUT1) ubiquitination and SUMOylation modifications were analyzed using co-immunoprecipitation and western blotting. CircRNF13 and Small Ubiquitin-like Modifier 2 (SUMO2) interactions were analyzed using RNA pull-down and luciferase reporter assays. Finally, to test whether circRNF13 inhibited NPC proliferation and metastasis in vivo, we used a xenograft nude mouse model generated by means of subcutaneous or tail vein injection. RESULTS: We found that circRNF13 was stably expressed at low levels in NPC clinical tissues and NPC cells. In vitro and in vivo experiments showed that circRNF13 inhibited NPC proliferation and metastasis. Moreover, circRNF13 activated the SUMO2 protein by binding to the 3'- Untranslated Region (3'-UTR) of the SUMO2 gene and prolonging the half-life of SUMO2 mRNA. Upregulation of SUMO2 promotes GLUT1 degradation through SUMOylation and ubiquitination of GLUT1, which regulates the AMPK-mTOR pathway by inhibiting glycolysis, ultimately resulting in the proliferation and metastasis of NPC. CONCLUSIONS: Our results revealed that a novel circRNF13 plays an important role in the development of NPC through the circRNF13-SUMO2-GLUT1 axis. This study implies that circRNF13 mediates glycolysis in NPC by binding to SUMO2 and provides an important theoretical basis for further elucidating the pathogenesis of NPC and targeted therapy.

背景：环状 RNA（circRNAs）广泛存在于人类细胞中，与癌症的发生发展密切相关。然而，在鼻咽癌（NPC）中很少对其进行研究。

方法：我们使用下一代 mRNA 测序筛选 NPC 细胞中的新环状 RNA circRNF13。使用逆转录聚合酶链反应和 RNA 荧光原位杂交检测 12 例非肿瘤鼻咽上皮（NPE）组织和 36 例 NPC 样本中 circRNF13 的表达。使用 MTT 和流式细胞术检测细胞增殖，使用集落形成实验检测集落形成能力。通过划痕愈合和 Transwell 分析分别分析细胞迁移和侵袭。使用 Seahorse 糖酵解应激试验分析细胞糖酵解。通过免疫共沉淀和 Western blot 分析葡萄糖转运蛋白 1（GLUT1）泛素化和 SUMO 化修饰。通过 RNA 下拉和荧光素酶报告基因分析检测 circRNF13 和 Small Ubiquitin-like Modifier 2（SUMO2）的相互作用。最后，通过皮下或尾静脉注射建立异种移植裸鼠模型，检测 circRNF13 对 NPC 增殖和转移的体内抑制作用。

结果：我们发现 circRNF13 在 NPC 临床组织和 NPC 细胞中稳定低水平表达。体外和体内实验表明，circRNF13 抑制 NPC 的增殖和转移。此外，circRNF13 通过与 SUMO2 基因的 3'-非翻译区（3'-UTR）结合并延长 SUMO2 mRNA 的半衰期，激活 SUMO2 蛋白。SUMO2 的上调通过 GLUT1 的 SUMO 化和泛素化促进 GLUT1 的降解，通过抑制糖酵解调节 AMPK-mTOR 通路，最终导致 NPC 的增殖和转移。

结论：我们的研究结果表明，一种新的 circRNF13 通过 circRNF13-SUMO2-GLUT1 轴在 NPC 的发生发展中发挥重要作用。该研究表明，circRNF13 通过与 SUMO2 结合介导 NPC 中的糖酵解，为进一步阐明 NPC 的发病机制和靶向治疗提供了重要的理论依据。