School of Pharmacy, Jiangxi Medical College, Nanchang University, Nanchang, 330006, China.
Key Laboratory of Drug Targets and Drug Screening of Jiangxi Province, Nanchang University, Nanchang, 330006, China.
Cell Death Dis. 2024 May 16;15(5):340. doi: 10.1038/s41419-024-06729-z.
Pancreatic cancer (PC) is among the deadliest malignancies, with an extremely poor diagnosis and prognosis. Gemcitabine (GEM) remains the first-line drug for treating PC; however, only a small percentage of patients benefit from current immunotherapies or targeted therapies. Resistance to GEM is prevalent and affects long-term survival. We found that ubiquitin-protein ligase E3 module N-recognition 5 (UBR5) is a therapeutic target against GEM resistance. UBR5 was markedly upregulated in clinical GEM-resistant PC samples and GEM-resistant PC cells. UBR5 knockdown markedly increased GEM sensitivity in GEM-resistant PC cell lines. UBR5-mediated GEM resistance was accompanied by activation of epithelial-mesenchymal transition (EMT) and could be mitigated by inhibiting EMT. Further analysis revealed that UBR5 promoted GEM resistance in PC cells by enhancing O-GlcNAcylation-mediated EMT. In addition, UBR5 knockdown resulted in increased O-GlcNAase (OGA) levels, an essential negatively regulated enzyme in the O-GlcNAcylation process. We identified a negative association between OGA and UBR5 levels, which further supported the hypothesis that O-GlcNAcylation-mediated GEM resistance induced by UBR5 is OGA-dependent in PC cells. Mechanistic studies revealed that UBR5 acts as an E3 ubiquitin ligase of OGA and regulates O-GlcNAcylation by binding and modulating OGA, facilitating its degradation and ubiquitination. Additionally, high-throughput compound library screening using three-dimensional protein structure analysis and drug screening identified a Food and Drug Administration drug, Y-39983 dihydrochloride, as a potent GEM sensitiser and UBR5 inhibitor. The combination of Y-39983 dihydrochloride and GEM attenuated tumour growth in a mouse xenograft tumour model. Collectively, these data demonstrated that UBR5 plays a pivotal role in the sensitisation of PC to GEM and provides a potential therapeutic strategy to overcome GEM resistance.
胰腺癌（PC）是最致命的恶性肿瘤之一，其诊断和预后极差。吉西他滨（GEM）仍然是治疗 PC 的一线药物；然而，只有一小部分患者受益于当前的免疫疗法或靶向疗法。对 GEM 的耐药性普遍存在，影响长期生存。我们发现泛素蛋白连接酶 E3 模块 N 识别 5（UBR5）是对抗 GEM 耐药性的治疗靶点。UBR5 在临床 GEM 耐药 PC 样本和 GEM 耐药 PC 细胞中明显上调。UBR5 敲低显著增加了 GEM 耐药 PC 细胞系的 GEM 敏感性。UBR5 介导的 GEM 耐药与上皮-间充质转化（EMT）的激活有关，并可以通过抑制 EMT 来减轻。进一步分析表明，UBR5 通过增强 O-GlcNAc 化介导的 EMT 来促进 PC 细胞中的 GEM 耐药。此外，UBR5 敲低导致 O-GlcNAcase（OGA）水平升高，OGA 是 O-GlcNAcylation 过程中必不可少的负调控酶。我们发现 OGA 和 UBR5 水平之间存在负相关，这进一步支持了 UBR5 通过 O-GlcNAc 化诱导的 GEM 耐药是 OGA 依赖性的假设在 PC 细胞中。机制研究表明，UBR5 是 OGA 的 E3 泛素连接酶，通过结合和调节 OGA 来调节 O-GlcNAc 化，促进其降解和泛素化。此外，使用三维蛋白质结构分析和药物筛选的高通量化合物文库筛选发现，一种美国食品和药物管理局批准的药物，Y-39983 二盐酸盐，是一种有效的 GEM 增敏剂和 UBR5 抑制剂。Y-39983 二盐酸盐和 GEM 的联合使用在小鼠异种移植肿瘤模型中抑制了肿瘤生长。总之，这些数据表明 UBR5 在 GEM 增敏 PC 中发挥关键作用，并为克服 GEM 耐药提供了一种潜在的治疗策略。
