UCH37通过Prdx1调控c-Myc介导的人肝癌复发的分子机制研究

The abnormal balance of protein ubiquitination and protein deubiquitination in the cells plays a crucial role in numerous biological processes and oncogenesis. Ubiquitin C-terminal hydrolase 37 (UCH37), a member of the ubiquitin C-terminal hydrolase (UCH) which is a subfamily of deubiquitinating enzymes (DUBs), is involved in such balance. In our preliminary work, clinicopathologic data showed that UCH37 was over-expressed in HCC cancerous tissues and was a significant predictor for time to recurrence (TTR). In vitro, we discovered that UCH37 could promote cell migration and invasion. Subsequently, co-immunoprecipitation (co-IP), GST pull-down assays and proteomic approaches were performed to screen UCH37-interacting proteins in HCC. Consequently, Prdx1, a tumor suppressor, and c-Myc oncogene were identified as two interacting with UCH37. In the current study, a large-scale and longer follow-up study will be performed to confirm the role of UCH37 in HCC recurrence. We will focus on the relationship between UCH37, Prdx1 and c-Myc, and gain an insight into mechanisms that UCH37, interacting with Prdx1, can stop it associating with c-Myc, which results in the activation of c-Myc pathway. Meanwhile, UCH37 can deubiquitinate c-Myc which leads to the accumulation of c-Myc in the cells. HCC recurrence is attributed to the activation of c-Myc signaling pathway.

UCH37是一种去泛素化酶，是调节蛋白质泛素化和去泛素化动态平衡的关键因子之一。课题组在前期工作中发现UCH37在肝癌组织中高表达，且是影响肝癌术后无瘤生存的独立危险因素；并发现UCH37能促进肿瘤细胞迁移和侵袭；通过蛋白质组学技术，筛选到与UCH37相互作用的两个蛋白质―Prdx1和c-Myc。Prdx1是一种抑癌基因，通过与c-Myc结合，特异性抑制c-Myc的转录活性。本课题将在既往工作的基础上，进一步扩大临床样本，验证UCH37高表达在肝癌术后转移复发中的作用，探索UCH37作用的关键靶分子。重点研究UCH37、Prdx1与c-Myc三者相互作用关系，拟证实UCH37在肝癌中高表达后与Prdx1相互作用，阻碍其与c-Myc结构域结合，减弱Prdx1抑制c-Myc转录活性的作用；同时，UCH37对c-Myc去泛素化调节，使其泛素降解减少而积累，通过上调c-Myc通路促进肝癌复发。

肝癌是世界范围内最常见的恶性肿瘤之一。肿瘤的转移和复发是目前临床肿瘤治疗和预防的最大挑战，因此，对肝癌转移复发相关因子的研究具有重要意义。. 课题组在前期工作中发现去泛素化酶37（UCH37）在肝癌组织中高表达，且是影响肝癌术后无瘤生存的独立危险因素；并发现UCH37能促进肝癌细胞迁移和侵袭；通过蛋白质组学技术，筛选到过氧化物酶1（PRDX1）与UCH37存在相互作用。PRDX1是过氧化物酶家族中分布最广泛的成员。PRDX1是一个促癌因子还是一个抑癌因子尚有争议，目前关于PRDX1与肝癌关系的报道甚少，本研究前期研究基础上，进一步研究PRDX1在肝癌组织中的表达情况及其与临床特征之间的关系，并探讨PRDX1与UCH37相互作用后对肝癌复发转移的影响。. 首先，我们采用免疫组化染色方法检测PRDX1在48例肝癌组织和相应癌旁组织中的表达情况。结果显示，PRDX1在肝癌组织中低表达。我们采用Cox风险比例模型，对肝癌患者术后总体生存时间（OS）和无瘤生存时间（DFS）相关危险因素进行了单因素和多因素分析。结果显示，PRDX1在癌旁组织中的免疫组化得分与相应癌组织中的得分之差大于等于2 分，是影响肝癌患者根治术后OS和DFS的独立危险因素。..随后，我们通过构建PRDX1过表达和下调的稳定的单克隆细胞株，并对其进行细胞功能实验研究。结果显示，PRDX1能显著抑制肝癌细胞的迁移和侵袭能力。.我们通过免疫共沉淀和激光共聚焦技术证实了PRDX1和UCH37之间存在相互作用。随后，我们在UCH37稳定过表达的单克隆细胞中构建PRDX1过表达及沉默细胞株，进一步探讨PRDX1与UCH37相互作用后对肝癌细胞的生物学行为的影响。结果显示，与对照相比，PRDX1过表达显著抑制UCH37所致的肝癌细胞的迁移和侵袭能力，沉默PRDX1则进一步增强UCH37所致的肝癌细胞的迁移和侵袭能力。. 综上所述，本课题证实PRDX1在肝癌组织中低表达，且是影响肝癌患者根治术后OS和DFS的独立危险因素；明确PRDX1具有抑制肝癌细胞迁移和侵袭的能力。同时，我们探讨了PRDX1通过与UCH37相互作用，拮抗了UCH37所致的肝癌细胞的迁移和侵袭能力，为寻找肝癌复发转移的治疗靶点提供新的方向。