Increased expression and nuclear localization of the centrosomal kinase Nek2 in human testicular seminomas

Protein kinases that regulate the centrosome cycle are often aberrantly controlled in neoplastic cells. Changes in their expression or activity can lead to perturbations in centrosome duplication, potentially leading to chromosome segregation errors and aneuploidy. Testicular germ cell tumours (TGCTs) are characterized by amplification of centrosomes through unknown mechanisms. Herein, we report that Nek2, a centrosomal kinase required for centrosome disjunction and formation of the mitotic spindle, is up‐regulated in human testicular seminomas as compared to control testes or other types of testicular germ cell tumours. In addition, Nek2 activity is also increased in human seminomas, as demonstrated by immunokinase assays. Analysis by immunohistochemistry indicated that Nek2 is prevalently localized in the nucleus of neoplastic cells of primary human seminomas. Such nuclear localization and the up‐regulation of Nek2 protein were also observed in the Tcam‐2 seminoma cell line. We demonstrate that nuclear localization of Nek2 is a feature of the more undifferentiated germ cells of mouse testis and correlates with expression of the stemness markers OCT4 and PLZF. These studies suggest that up‐regulation of Nek2 is a frequent event in human seminomas and that this may participate in the onset or progression of neoplastic transformation through deregulation of centrosome duplication and/or nuclear events in germ cells. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

[1]  P. Chieffi,et al.  PATZ1 gene has a critical role in the spermatogenesis and testicular tumours , 2008, The Journal of pathology.

[2]  S. Kitazawa,et al.  Further characterization of the first seminoma cell line TCam‐2 , 2008, Genes, chromosomes & cancer.

[3]  R. Geremia,et al.  Potential role of Nanos3 in maintaining the undifferentiated spermatogonia population. , 2008, Developmental biology.

[4]  G. Botti,et al.  Detection of high‐mobility group proteins A1 and A2 represents a valid diagnostic marker in post‐pubertal testicular germ cell tumours , 2008, The Journal of pathology.

[5]  M. Nagino,et al.  Nek2 as an effective target for inhibition of tumorigenic growth and peritoneal dissemination of cholangiocarcinoma. , 2007, Cancer research.

[6]  E. F. da Cruz e Silva,et al.  Alternative Splicing Controls Nuclear Translocation of the Cell Cycle-regulated Nek2 Kinase* , 2007, Journal of Biological Chemistry.

[7]  David M. Glover,et al.  Centrosome biogenesis and function: centrosomics brings new understanding , 2007, Nature Reviews Molecular Cell Biology.

[8]  R. Wolthuis,et al.  Cyclin B1–Cdk1 Activation Continues after Centrosome Separation to Control Mitotic Progression , 2007, PLoS biology.

[9]  R. Brinster.  Male Germline Stem Cells: From Mice to Men , 2007, Science.

[10]  E. Nigg,et al.  Origins and consequences of centrosome aberrations in human cancers , 2006, International journal of cancer.

[11]  P. Cooke,et al.  Mechanistic Insights into the Regulation of the Spermatogonial Stem Cell Niche , 2006, Cell cycle.

[12]  P. Chieffi,et al.  17‐β‐estradiol elicits genomic and non‐genomic responses in mouse male germ cells , 2006 .

[13]  A. Hart,et al.  The pluripotency homeobox gene NANOG is expressed in human germ cell tumors , 2005, Cancer.

[14]  Christopher J. Wilkinson,et al.  Rootletin forms centriole-associated filaments and functions in centrosome cohesion , 2005, The Journal of cell biology.

[15]  Dannel McCollum,et al.  Centrosomes in cellular regulation. , 2005, Annual review of cell and developmental biology.

[16]  L. Looijenga,et al.  Testicular germ-cell tumours in a broader perspective , 2005, Nature Reviews Cancer.

[17]  W. Saunders.  Centrosomal amplification and spindle multipolarity in cancer cells. , 2005, Seminars in cancer biology.

[18]  J. Maller,et al.  A Centrosomal Localization Signal in Cyclin E Required for Cdk2-Independent S Phase Entry , 2004, Science.

[19]  Andrew M Fry,et al.  The Centrosomal Kinase Nek2 Displays Elevated Levels of Protein Expression in Human Breast Cancer , 2004, Cancer Research.

[20]  O. Lacham-Kaplan,et al.  In vivo and in vitro differentiation of male germ cells in the mouse. , 2004, Reproduction.

[21]  S. Di Agostino,et al.  Meiotic progression of isolated mouse spermatocytes under simulated microgravity. , 2004, Reproduction.

[22]  Erich A. Nigg,et al.  Polo-like kinases and the orchestration of cell division , 2004, Nature Reviews Molecular Cell Biology.

[23]  P. Pandolfi,et al.  Essential role of Plzf in maintenance of spermatogonial stem cells , 2004, Nature Genetics.

[24]  R. Braun,et al.  Plzf is required in adult male germ cells for stem cell self-renewal , 2004, Nature Genetics.

[25]  Erich A Nigg,et al.  Aurora kinases link chromosome segregation and cell division to cancer susceptibility. , 2004, Current opinion in genetics & development.

[26]  P. Chieffi,et al.  Phosphorylation of high-mobility group protein A2 by Nek2 kinase during the first meiotic division in mouse spermatocytes. , 2003, Molecular biology of the cell.

[27]  A. Fry,et al.  Nek2A kinase stimulates centrosome disjunction and is required for formation of bipolar mitotic spindles. , 2003, Molecular biology of the cell.

[28]  S. Sen,et al.  Aneuploidy of human testicular germ cell tumors is associated with amplification of centrosomes , 2003, Oncogene.

[29]  J. Kononen,et al.  POU5F1 (OCT3/4) identifies cells with pluripotent potential in human germ cell tumors. , 2003, Cancer research.

[30]  G. Pihan,et al.  Centrosome abnormalities and chromosome instability occur together in pre-invasive carcinomas. , 2003, Cancer research.

[31]  J. Pines,et al.  Active cyclin B1–Cdk1 first appears on centrosomes in prophase , 2003, Nature Cell Biology.

[32]  T. Grogan,et al.  Gene Expression Profile of Serial Samples of Transformed B-Cell Lymphomas , 2003, Laboratory Investigation.

[33]  A. Fry.  The Nek2 protein kinase: a novel regulator of centrosome structure , 2002, Oncogene.

[34]  H. Schöler,et al.  Oct4 distribution and level in mouse clones: consequences for pluripotency. , 2002, Genes & development.

[35]  D. Garbers,et al.  Male germ cell specification and differentiation. , 2002, Developmental cell.

[36]  S. Di Agostino,et al.  The MAPK pathway triggers activation of Nek2 during chromosome condensation in mouse spermatocytes. , 2002, Development.

[37]  Toshifumi Ozaki,et al.  Expression analysis of pediatric solid tumor cell lines using oligonucleotide microarrays. , 2002, International journal of oncology.

[38]  S. Lauer,et al.  Multipoint imprinting analysis indicates a common precursor cell for gonadal and nongonadal pediatric germ cell tumors. , 2001, Cancer research.

[39]  T. Mayor,et al.  The Centrosomal Protein C-Nap1 Is Required for Cell Cycle–Regulated Centrosome Cohesion , 2000, The Journal of cell biology.

[40]  E. Schröck,et al.  Centrosome amplification and instability occurs exclusively in aneuploid, but not in diploid colorectal cancer cell lines, and correlates with numerical chromosomal aberrations , 2000, Genes, chromosomes & cancer.

[41]  M. Conti,et al.  Activation of the Mitogen-activated Protein Kinase ERK1 during Meiotic Progression of Mouse Pachytene Spermatocytes* , 1999, The Journal of Biological Chemistry.

[42]  P. Meraldi,et al.  C-Nap1, a Novel Centrosomal Coiled-Coil Protein and Candidate Substrate of the Cell Cycle–regulated Protein Kinase Nek2 , 1998, The Journal of cell biology.

[43]  P. Meraldi,et al.  A centrosomal function for the human Nek2 protein kinase, a member of the NIMA family of cell cycle regulators , 1998, The EMBO journal.

[44]  D. Wolgemuth,et al.  The NIMA-related kinase 2, Nek2, is expressed in specific stages of the meiotic cell cycle and associates with meiotic chromosomes. , 1997, Development.

[45]  M. Pesce,et al.  Purification of mouse primordial germ cells by MiniMACS magnetic separation system. , 1995, Developmental biology.

[46]  J. Bartek,et al.  Substrate Specificity and Cell Cycle Regulation of the Nek2 Protein Kinase, a Potential Human Homolog of the Mitotic Regulator NIMA of Aspergillus nidulans(*) , 1995, The Journal of Biological Chemistry.

[47]  T. Ulbright.  Germ Cell Neoplasms of the Testis , 1993, The American journal of surgical pathology.

[48]  J. Millán,et al.  Immortalization of germ cells and somatic testicular cells using the SV40 large T antigen. , 1992, Experimental cell research.

[49]  P. Rossi,et al.  Author ' s personal copy Transcriptome analysis of differentiating spermatogonia stimulated with kit ligand , 2007 .

[50]  P. Casey,et al.  beta-Catenin is a Nek2 substrate involved in centrosome separation. , 2008, Genes & development.

[51]  P. Rossi,et al.  Follicle-stimulating hormone induction of steel factor (SLF) mRNA in mouse Sertoli cells and stimulation of DNA synthesis in spermatogonia by soluble SLF. , 1993, Developmental biology.