去泛素化酶USP14调控细胞周期相关蛋白在原发性肝细胞癌增殖中的机制和功能研究

Hepatocellular carcinoma (HCC) is one of the most frequent tumors worldwide. Hepatic resection is a well-accepted therapy for HCC, but many patients are unable to surgery because of late HCC diagnosis, and alternative treatments do not substantially improve the patients' prognosis when HCC is unresectable. The investigation of molecular mechanisms leading to HCC development and progression is mandatory to identify new targets for its early diagnosis and treatment. .Dysfunction of the ubiquitin proteasome system (UPS) has been implicated in numerous diseases, the preeminent of which is cancer. In our previous study, we found that the ubiquitin-specific peptidase 14（USP14） expression in the HCC tissues was significantly higher than those in the adjacent non-cancerous liver and normal liver tissue. Moreover, increased USP14 expression was associated with certain clinical pathological variables, such as advancing tumor stage. The Kaplan-Meier analysis demonstrated that HCC patients with USP14 overexpression had a significantly poor prognosis after surgery, compared with the patients with decreased levels of USP14. Knockdown of USP14 in SMMC7721 cells with siRNA and shRNA-lentivirus can suppress cell proliferation and induce cell apoptosis. These findings strongly suggest that USP14 activation might play an oncogenic role in promoting tumor progression of HCC. .Consistent with this idea, the biological role of USP14 activation in HCC progression will be investigated in this study. We propose USP14 can affect cell cycle through the regulation to other regulators, such as cyclin A,B,D,E and CDKs. Thus, these roles likely reflect that USP14 can play a core role in pathological processes, and the identification of USP14 and USP14-driven genes promote the exploration of its functional role in multiple cooperating oncogenic pathways. On the basis of this background, we want to investigate the relationship between USP14 and the potential targets, especially cell-cycle-associated proteins. Further research is needed to validate this hypothesis through a cell biological study. Next we attempt to clarify whether USP14 overexpression affects the clinicopathological features of HCC by use of a large sample and to investigate possible mechanisms leading to HCC development and progression..In conclusion, this study could provide a new research direction of malignant regulation mechanism of HCC initiation and progression. On the other hand, we want to find a potential target of HCC.

我们在对大量原发性肝癌样本的表达谱分析中发现去泛素化酶家族中USP14特异性的在肝癌组织中高表达，并在mRNA和蛋白水平进行确认。随访发现USP14高表达患者其肿瘤分期及预后均较差。进一步在肝癌细胞系SMMC7721中发现USP14表达较高，敲减USP14后，细胞周期明显改变，增殖明显抑制，凋亡比例增多，初步发现USP14可能具有促进肝癌生长的作用。再结合相关领域文献，我们认为USP14可能通过影响细胞周期相关蛋白稳定性对肝癌细胞的增殖调控起到关键作用。我们将首先通过大样本的免疫组化来进一步验证USP14的表达与肝癌分期及预后的相关性。进而再通过多种肝癌细胞系的体外、体内实验，研究该基因对肝癌细胞生物学特性的影响。并希望能在机制方面明确该基因与细胞周期调控相关蛋白之间的调控关系。最终为原发性肝癌发生发展的恶性异常调控机制相关研究打开新的切入点，同时为原发性肝癌的综合治疗提供新的治疗靶点。

肝癌是一种世界范围内常见的恶性肿瘤，肝癌的死亡率在所有恶性肿瘤中居第三位。全世界半数左右的肝癌病人集中在中国，其致死率居我国所有肿瘤的第二位。虽然随着科技的进步，在肝癌的治疗方面已经取得了巨大的进展，但是临床肝癌诊疗中仍然存在的早期诊断难、复发转移率高、缺乏有效治疗靶点等问题亟待解决。寻找相关标志物和干预靶点是当前肝癌研究的热点，近年来去泛素化酶及其相关底物蛋白在肿瘤发生发展中的作用机制受到进一步重视，目前对其精确的分子机制尚未完全清楚。因此, 进一步探索研究相关基因功能改变与肝癌发生发展及其恶性特征的关系，对揭示其发生发展的分子机制、寻找合理的靶向治疗药物以及判断预后具有重要意义，进而提高我国肝癌的综合治疗水平。我们在对大量原发性肝癌样本的表达谱分析中发现去泛素化酶家族中USP14 特异性的在肝癌组织中高表达，并在mRNA和蛋白水平进行确认。通过对肝癌患者病理结果及生存分析发现USP14高表达患者其肿瘤分期及预后均较差。进一步在肝癌细胞系SMMC7721中发现USP14表达较高，敲减USP14后，细胞周期明显改变，增殖明显抑制，凋亡比例增多，发现USP14可能具有促进肝癌生长的作用。然后通过较大样本的免疫组化进一步验证了USP14的表达与肝癌分期及预后的相关性。并通过多种肝癌细胞系的体外、体内实验，发现该基因对肝癌细胞生物学特性的影响。进一步的机制研究发现Wnt/β-catenin通路可能在USP14对肝癌细胞的增殖调控起到关键作用。这一研究最终为肝癌发生发展的恶性异常调控机制等相关研究打开新的切入点，并为肝癌的综合治疗提供了可能的新治疗靶点。