Nucleostemin/GNL3 promotes nucleolar polyubiquitylation of p27kiP1 to drive hepatocellular carcinoma progression-猫眼课题宝

Nucleostemin/GNL3 促进 p27(kiP1) 核仁多泛素化以驱动肝细胞癌进展

DOI：

10.1016/j.canlet.2016.12.008

发表时间：

2017-03-01

期刊：

CANCER LETTERS

影响因子：

9.7

通讯作者：

中科院分区：

医学1区

文献类型：

--

作者：

Hu, Baoying;Hua, Lu;Wan, Chunhua

p27（kip）作为细胞周期蛋白依赖性激酶抑制剂（CDKI），在细胞周期调控和肝癌发生发展中起重要作用。在此，我们揭示了p27在肝细胞癌（HCC）细胞中具有明显的核仁分布，并与核仁蛋白核干细胞蛋白（NS）相互作用。此外，亚细胞分级实验表明，核仁p27具有显着更高的水平的多泛素化，相比，核质级分。NS的耗竭抑制了p27的核仁多聚泛素化，表明NS参与了HCC发展过程中触发p27泛素化和失活。此外，我们发现NS的敲低促进p27与CDK 2-Cyclin E复合物结合，抑制CDK 2的活性，导致HCC细胞的细胞周期停滞。此外，沉默NS表达减少了HCC细胞的体外集落形成和体内肿瘤生长。最后，我们发现NS在HCC组织中与邻近的非肿瘤组织相比表达上调。Kaplan-Meier分析显示NS高表达和p27低表达患者的预后明显恶化。我们的研究结果表明，NS介导的p27依赖的细胞周期控制通过诱导核仁隔离和p27的多泛素化。这些发现有助于深入了解肝癌发生过程中细胞周期进程异常的机制，从而有利于肝癌分子靶向治疗的发展。(C)2016爱思唯尔爱尔兰有限公司版权所有。

p27(kip), as a cyclin dependent kinase inhibitor (CDKI), plays a pivotal role in the regulation of cell cycle progression and hepatocarcinogenesis. Herein, we revealed that p27 exhibited apparent nucleolar distribution and interacted with nucleolar protein nucleostemin (NS) in Hepatocellular carcinoma (HCC) cells. Furthermore, subcellular fractionation experiments demonstrated that nucleolar p27 had significantly higher level of polyubiquitylation, compared with nucleoplasmic fraction. Depletion of NS inhibited nucleolar polyubiquitylation of p27, indicating an involvement of NS in triggering p27 ubiquitylation and inactivation during HCC development. Moreover, we found that knockdown of NS promoted p27 to bind to CDK2-Cyclin E complex and inhibited the activity of CDK2, resulting in consequent cell cycle arrest in HCC cells. Furthermore, silencing NS expression reduced in vitro colony formation and in vivo tumor growth of HCC cells. Finally, we found that NS was upregulated in HCC tissues, compared with adjacent non-tumorous tissues. Kaplan-Meier analysis indicated patients with high expression of NS and low expression of p27 had significantly worsened prognosis. Our results suggested NS mediated p27 dependent cell cycle control via inducing nucleolar sequestration and polyubiquitylation of p27 in HCC. These findings help gain an insightful view into the mechanism underlying aberrant cell cycle progression during hepatocarcinogenesis, and thus benefit the development of molecular-targeted therapies in HCC. (C) 2016 Elsevier Ireland Ltd. All rights reserved.