title: Nucleoporin 62 and Ca(2+)/calmodulin dependent kinase kinase 2 regulate androgen receptor activity in castrate resistant prostate cancer cells.
abstract: BACKGROUND
  Re-activation of the transcriptional activity of the androgen receptor (AR) is an important factor mediating progression from androgen-responsive to castrate-resistant prostate cancer (CRPC). However, the mechanisms regulating AR activity in CRPC remain incompletely understood. Ca(2+) /calmodulin-dependent kinase kinase (CaMKK) 2 was previously shown to regulate AR activity in androgen-responsive prostate cancer cells. Our objective was to further explore the basis of this regulation in CRPC cells.
  
  
  METHODS
  The abundance of CaMKK2 in nuclear fractions of androgen-responsive prostate cancer and CRPC, cells were determined by subcellular fractionation and Western blotting. CaMKK2 association with nuclear pore complexes (NPCs) and nucleoporins (Nups) including Nup62, were imaged by structured illumination and super-resolution fluorescence microscopy and co-immunoprecipitation, respectively. The abundance and subcellular localization of CaMKK2 and Nup62 in human clinical specimens of prostate cancer was visualized by immunohistochemistry. The role of Nups in the growth and viability of CRPC cells was assessed by RNA interference and cell counting. The involvement of CaMKK2 and Nup62 in regulating AR transcriptional activity was addressed by RNA interference, chromatin immunoprecipitation, androgen response element reporter assay, and Western blotting.
  
  
  RESULTS
  CaMKK2 was expressed at higher levels in the nuclear fraction of CPRC C4-2 cells, than in that of androgen-responsive LNCaP cells. In C4-2 cells, CaMKK2 associated with NPCs of the nuclear envelope and physically interacted with Nup62. CaMKK2 and Nup62 demonstrated pronounced, and similar increases in both expression and perinuclear/nuclear localization in human clinical specimens of advanced prostate cancer relative to normal prostate. Knockdown of Nup62, but not of Nups, 98 or 88, reduced growth and viability of C4-2 cells. Knockdown of Nup62 produced a greater reduction of the growth and viability of C4-2 cells than of non-neoplastic RWPE-1 prostatic cells. Nup62, CaMKK2, and the AR were recruited to androgen response elements of the AR target genes, prostate specific antigen, and transmembrane protease, serine 2. Knockdown of CaMKK2 and Nup62 reduced prostate specific antigen expression and AR transcriptional activity driven by androgen response elements from the prostate-specific probasin gene promoter.
  
  
  CONCLUSIONS
  Nup62 and CaMKK2 are required for optimal AR transcriptional activity and a potential mechanism for AR re-activation in CRPC.
authors.affiliation: Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, New York.
authors.forename: Loukia G
authors.initials: LG
authors.lastname: Karacosta
authors.affiliation: Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, New York.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Kuroski
authors.affiliation: Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York.
authors.forename: Wilma A
authors.initials: WA
authors.lastname: Hofmann
authors.affiliation: Department of Pathology and Laboratory Medicine, Roswell Park Cancer Institute, Buffalo, New York.
authors.forename: Gissou
authors.initials: G
authors.lastname: Azabdaftari
authors.affiliation: Department of Biochemistry, State University of New York at Buffalo, Buffalo, New York.
authors.forename: Michalis
authors.initials: M
authors.lastname: Mastri
authors.affiliation: Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, New York.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Gocher
authors.affiliation: Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, New York.
authors.forename: Shuhang
authors.initials: S
authors.lastname: Dai
authors.affiliation: Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York.
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Hoste
authors.affiliation: Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, New York.
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Edelman
mesh_terms: D014408:Biomarkers, Tumor / Q000096:biosynthesis* / Q000235:genetics; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase / Q000096:biosynthesis* / Q000235:genetics; D045744:Cell Line, Tumor; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D028861:Nuclear Pore Complex Proteins / Q000096:biosynthesis* / Q000235:genetics; D064129:Prostatic Neoplasms, Castration-Resistant / Q000235:genetics / Q000378:metabolism*; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*
chemical_list: C410798:AR protein, human; D014408:Biomarkers, Tumor; D008562:Membrane Glycoproteins; D028861:Nuclear Pore Complex Proteins; D011944:Receptors, Androgen; C049312:nuclear pore protein p62; C517698:CAMKK2 protein, human; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase
keywords: nuclear envelope; protein phosphorylation; transcriptional activity