title: Nucleostemin/GNL3 promotes nucleolar polyubiquitylation of p27kip1to drive hepatocellular carcinoma progression.
abstract: p27kip, 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.
authors.affiliation: Department of Radiotherapy, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China; Jiangsu Province Key Laboratory for Inﬂammation and Molecular Drug Target, Nantong University, Nantong 226001, Jiangsu Province, China; Basic Medical Research Centre, Medical College, Nantong University, Nantong 226001, Jiangsu Province, China.
authors.forename: Baoying
authors.initials: B
authors.lastname: Hu
authors.affiliation: Department of Radiotherapy, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China; Jiangsu Province Key Laboratory for Inﬂammation and Molecular Drug Target, Nantong University, Nantong 226001, Jiangsu Province, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Hua
authors.affiliation: Department of Gastroenterlogy, Afﬁliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China.
authors.forename: Wenkai
authors.initials: W
authors.lastname: Ni
authors.affiliation: Jiangsu Province Key Laboratory for Inﬂammation and Molecular Drug Target, Nantong University, Nantong 226001, Jiangsu Province, China.
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Wu
authors.affiliation: Jiangsu Province Key Laboratory for Inﬂammation and Molecular Drug Target, Nantong University, Nantong 226001, Jiangsu Province, China.
authors.forename: Daliang
authors.initials: D
authors.lastname: Yan
authors.affiliation: Class 2 Grade 13, Clinical Medicine, Medical College, Nantong University, Nantong 226001, Jiangsu Province, China.
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Gastroenterlogy, Afﬁliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China.
authors.forename: Cuihua
authors.initials: C
authors.lastname: Lu
authors.affiliation: Department of Radiotherapy, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China. Electronic address: chenbuyou1954@163.com.
authors.forename: Buyou
authors.initials: B
authors.lastname: Chen
authors.affiliation: Jiangsu Province Key Laboratory for Inﬂammation and Molecular Drug Target, Nantong University, Nantong 226001, Jiangsu Province, China. Electronic address: Chwan@ntu.edu.cn.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Wan
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D009687:Nuclear Proteins / Q000378:metabolism*; D014162:Transfection
chemical_list: C524643:GNL3L protein, mouse; D009687:Nuclear Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D019204:GTP-Binding Proteins
keywords: Cell cycle regulation; Heptocellular carcinoma; Nucleolar ubiquitylation; Nucleostemin; p27