title: Corepressive function of nuclear receptor coactivator 2 in androgen receptor of prostate cancer cells treated with antiandrogen.
abstract: Recruitment of cofactors in the interaction of the androgen receptor (AR) and AR ligands plays a critical role in determining androgenic/antiandrogenic effects of the AR ligand on signaling, but the functions of key cofactors, including nuclear receptor coactivator (NCOA), remain poorly understood in prostate cancer cells treated with AR ligands.
  
  
  
  We examined prostate cancer cell lines LNCaP and VCaP expressing mutated and wild-type ARs, respectively, to clarify the significance of NCOAs in the effect of antiandrogens. Hydroxyflutamide showed antagonistic activity against VCaP and an agonistic effect on LNCaP. Bicalutamide served as an antagonist for both. We analyzed mRNA transcription and protein expression of NCOAs in these cells pretreated with dihydrotestosterone and thereafter treated with the mentioned antiandrogens. Transcriptional silencing of candidate NCOAs and AR was performed using small interfering RNA (siRNA). Cell proliferation was evaluated with MTT assay.
  
  
  
  LNCaP treated with bicalutamide showed an about four-fold increase in the expression of NCOA2 mRNA compared to those pretreated with dihydrotestosterone alone (P <0.01). In VCaP pretreated with dihydrotestosterone, transcriptions of NCOA2 and NCOA7 were slightly increased with bicalutamide (1.96- and 2.42-fold, respectively) and hydroxyflutamide (1.33-fold in both). With Western blotting, the expression of NCOA2 protein also increased in LNCaP cells treated with bicalutamide compared with that in control cells pretreated with dihydrotestosterone alone. Following silencing with siRNA for NCOA2, PSA levels in media with LNCaP receiving bicalutamide were elevated compared with those in non-silencing controls (101.6 ± 4.2 vs. 87.8 ± 1.4 ng/mL, respectively, P =0.0495). In LNCaP cells treated with dihydrotestosterone and bicalutamide, NCOA2-silencing was associated with a higher proliferation activity compared with non-silencing control and AR-silencing.
  
  
  
  NCOA2, which has been thought to be recruited as a coactivator, possibly plays a corepressive role in AR of prostate cancer cells when treated with antiandrogens, suggesting its potential as a therapeutic target.
authors.affiliation: Division of Urology, Department of Regenerative and Transplant Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Division of Urology, Department of Regenerative and Transplant Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan. harasho@med.niigata-u.ac.jp.|Division of Molecular Oncology, Department of Signal Transduction Research, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan. harasho@med.niigata-u.ac.jp.|, Asahimachi 1, Niigata, 951-8510, Japan. harasho@med.niigata-u.ac.jp.
authors.forename: Noboru
authors.initials: N
authors.lastname: Hara
authors.affiliation: Division of Urology, Department of Regenerative and Transplant Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nishiyama
authors.affiliation: Division of Urology, Department of Regenerative and Transplant Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Tasaki
authors.affiliation: Division of Urology, Department of Regenerative and Transplant Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Ishizaki
authors.affiliation: Division of Urology, Department of Regenerative and Transplant Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Tomita
mesh_terms: D000726:Androgen Antagonists / Q000494:pharmacology*; D000813:Anilides / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D013196:Dihydrotestosterone / Q000494:pharmacology*; D005485:Flutamide / Q000031:analogs & derivatives / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008297:Male; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D056918:Nuclear Receptor Coactivators / Q000235:genetics* / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism*; D011944:Receptors, Androgen / Q000235:genetics*; D014105:Tosyl Compounds / Q000494:pharmacology
chemical_list: C410798:AR protein, human; D000726:Androgen Antagonists; D000813:Anilides; D009570:Nitriles; D056918:Nuclear Receptor Coactivators; D011944:Receptors, Androgen; D014105:Tosyl Compounds; D013196:Dihydrotestosterone; C014290:hydroxyflutamide; D005485:Flutamide; C053541:bicalutamide
keywords: Androgen receptor; Antiandrogen; Coactivator; Corepressor