去泛素化酶PSMD14促进肝癌生长和转移的分子机制

Abnormal expression of deubiquitinase is closely associated with malignancies. The deubiquitinase PSMD14 have been previously demonstrated to play important roles in multiple biological processes. However, its functions, interacted proteins and the regulatory mechanism of its target genes in hepatocellular carcinoma (HCC) remain poorly understood. Our present study demonstrated that PSMD14 was upregulated in HCC samples, and promoted growth and metastasis in HCC. Our preliminary results from co-immunoprecipitaton and mass spectrum analysis showed that PSMD14 interacted with growth factor receptor-bound protein 2 (GRB2), and regulated GRB2 stability. We also found that MMP-9, STMN1 and PTTG1 were the direct target genes of PSMD14 through ChIP-seq and RNA-seq analysis. Thus, in this study, we will reveal the molecular mechanism by which PSMD14 regulates the ubiquitination of GRB2, and determine the PSMD14-GRB2-induced biological behavior and downstream signaling pathway, and further explore the underlying mechanisms by which PSMD14 regulates target genes expression, and reveal the clinical significance of PSMD14/GRB2 and PSMD14/target genes. We reveal the molecular network mediated by PSMD14 in HCC growth and metastasis through integrating mass spectrum, ChIP-seq and RNA-seq data, which may be of great importance for the diagnosis and treatment of HCC by using PSMD14 as a biological marker.

去泛素化酶的异常表达与多种恶性肿瘤密切相关，去泛素化酶PSMD14在多种生物学过程中发挥重要作用，但在肝癌中的功能、相互作用的蛋白及调控下游基因表达的分子机制尚未完全阐明。我们前期发现：PSMD14在肝癌组织中显著高表达,并促进肝癌细胞生长和转移；通过免疫共沉淀联合蛋白质谱分析，并证实PSMD14能与GRB2相互作用及促进GRB2蛋白稳定性；通过ChIP-seq和RNA-seq筛选，初步证实MMP-9、STMN1及PTTG1为核内PSMD14靶基因。本研究将进一步明确PSMD14调控GRB2泛素化的机制、介导的生物学行为及下游信号通路；明确PSMD14直接调控的下游靶基因及分子机制；明确PSMD14/GRB2和PSMD14/下游靶基因的临床意义。本研究从多组学数据的整合性分析入手，阐明PSMD14所调控的关键分子网络在肝癌生长和转移中的作用，对以PSMD14为靶点的肝癌诊断及治疗提供依据。

肝癌是我国最常见的消化系统恶性肿瘤之一，其恶性程度高，预后差。先前的研究已报道异常的蛋白质泛素化修饰参与调控肝癌的恶性进展。在本项目中，我们发现去泛素化酶PSMD14在肝癌组织中显著高表达，与血管侵犯、肿瘤复发相关，并与无瘤生存期和总生存期呈负相关。体内外的功能实验结果显示，PSMD14能促进肝癌的生长和转移能力。进一步机制研究发现，PSMD14可与衔接蛋白GRB2结合，促进GRB2蛋白发生K48和K63去泛素化，从而抑制GRB2的泛素化降解，上调GRB2表达水平。同时，PSMD14还能影响GRB2下游AKT，STAT3及ERK1/2通路的激活。我们利用PSMD14的小分子抑制剂OPA处理肝癌细胞，发现OPA能显著抑制肝癌细胞增殖和转移。综上，我们的发现表明PSMD14可能可以作为治疗肝癌的有效靶点之一。