title: [The roles of c-Jun and CBP in the inhibitory effect of quercetin on prostate cancer cells].
abstract: OBJECTIVE
  To further uncover the possible mechanism of quercetin-mediated inhibitory effect on prostate cancer cells.
  
  
  METHODS
  The cell extracts treated with quercetin or without treatment were used for checking protein expression levels of c-Jun and cAMP response element binding protein (CREB)-binding protein (CBP) by Western blotting assay. Regulatory effects of c-Jun and CBP on the function of androgen receptor (AR) were examined by cotransfection experiment. Finally, a physical interaction of c-Jun and the AR was investigated by coimmunoprecipitation.
  
  
  RESULTS
  Quercetin dramatically induced the protein expression of c-Jun which in turn inhibited the AR function. Meanwhile, quercetin had no detectable effect on CBP expression, and the results of transient transfection demonstrated that the ectopic CBP stimulated the transcriptional activity of AR, whereas CBP-mediated stimulation could be attenuated by quercetin. Furthermore, physical interaction of c-Jun and the AR was confirmed by coimmunoprecipitation result.
  
  
  CONCLUSIONS
  Overexpression of c-Jun induced by quercetin had inhibitory effect on the function of AR protein, and increased CBP expression did not reverse the inhibition by quercetin. Together, quercetin-mediated inhibition on the AR function might be not by competition with limited amount of CBP in the cell, but through a direct association of c-Jun and the AR.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Medicine, Shandong University, Jinan 250012, China.
authors.forename: Hui-qing
authors.initials: HQ
authors.lastname: Yuan
authors.forename: Huai-fang
authors.initials: HF
authors.lastname: Guo
authors.forename: Mei-lan
authors.initials: ML
authors.lastname: He
authors.forename: Feng
authors.initials: F
authors.lastname: Kong
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Hu
authors.forename: An-li
authors.initials: AL
authors.lastname: Jiang
authors.forename: Xia
authors.initials: X
authors.lastname: Xu
authors.forename: Jian-ye
authors.initials: JY
authors.lastname: Zhang
authors.forename: Y F Young
authors.initials: YF
authors.lastname: Charles
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D050882:CREB-Binding Protein / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D045744:Cell Line, Tumor; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology; D011485:Protein Binding / Q000187:drug effects; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D011794:Quercetin / Q000494:pharmacology*; D011944:Receptors, Androgen / Q000235:genetics / Q000502:physiology; D014162:Transfection
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D016755:Proto-Oncogene Proteins c-jun; D011944:Receptors, Androgen; D011794:Quercetin; D050882:CREB-Binding Protein