title: Pirin down-regulates the EAF2/U19 protein and alleviates its growth inhibition in prostate cancer cells.
abstract: BACKGROUND
  The tumor suppressor ELL associated factor 2 (EAF2/U19) has been reported to induce apoptosis of LNCaP cells and suppress AT6.1 xenograft prostate tumor growth. EAF2/U19 expression level is down-regulated in advanced human prostate cancer. EAF2/U19 is also a putative transcription factor with a transactivation domain and capability of sequence-specific DNA binding. Identification of binding partners and regulators of EAF2/U19 is essential to understand its function in regulating apoptosis/survival of prostate cancer cells.
  
  
  METHODS
  Through a yeast two-hybrid screening system, we identified Pirin as a binding partner of EAF2. We further determined the interaction between epitope-tagged EAF2/U19 and Pirin by co-immunoprecipitation in mammalian cells. The effect of Pirin on EAF2/U19 inhibition of LNCaP growth was assayed by colony formation.
  
  
  RESULTS
  Pirin co-immunoprecipitated with EAF2/U19 and the overexpressed Pirin decreased the expression level of EAF2/U19 protein in prostate cancer cell lines LNCaP and PC3. Furthermore, overexpression of EAF2/U19 suppressed LNCaP colony formation, and co-expression of Pirin significantly blocked the growth inhibition induced by EAF2/U19 overexpression.
  
  
  CONCLUSIONS
  Pirin is a newly identified binding partner of EAF2/U19 capable of down-regulating EAF2/U19 protein and alleviating its inhibition of prostate cancer cell survival/proliferation. Pirin may play an important role involved in EAF2/U19 function as an androgen-responsive gene and tumor repressor.
authors.affiliation: Department of Urology, The 3rd Affiliated Hospital, Harbin Medical University, Harbin, Heilongjiang, China; Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Zhongjie
authors.initials: Z
authors.lastname: Qiao
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.forename: Junghyun
authors.initials: J
authors.lastname: Hahn
authors.forename: Junkui
authors.initials: J
authors.lastname: Ai
authors.forename: Zhou
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000503:physiopathology; D017209:Apoptosis / Q000502:physiology; D063646:Carcinogenesis / Q000473:pathology; D002352:Carrier Proteins / Q000502:physiology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival / Q000502:physiology; D049308:Dioxygenases; D015536:Down-Regulation / Q000502:physiology*; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D009687:Nuclear Proteins / Q000502:physiology*; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000503:physiopathology; D011485:Protein Binding / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology*
chemical_list: D002352:Carrier Proteins; C472771:EAF2 protein, human; D009687:Nuclear Proteins; D014157:Transcription Factors; D049308:Dioxygenases; C105340:PIR protein, human
keywords: EAF2/U19; Pirin; prostate cancer