title: Bisbibenzyls, novel proteasome inhibitors, suppress androgen receptor transcriptional activity and expression accompanied by activation of autophagy in prostate cancer LNCaP cells.
abstract: BACKGROUND
  Bisbibenzyl compounds have gained our interests for their potential antitumor activity in malignant cell-types.
  
  
  OBJECTIVE
  The objective of this study is to investigate the effect of bisbibenzyl compounds riccardin C (RC), marchantin M (MM), and riccardin D (RD) on androgen receptor (AR) in prostate cancer (PCa) cells.
  
  
  METHODS
  After exposure to 10 μM of the compounds for 24 h, cell cycle and cell survival analyses were performed using FACS and MTT assay to confirm the effect of these bisbibenzyls on PCa LNCaP cells. Changes in the AR expression and function, as the result of exposure to the compounds, were investigated using real-time PCR, ELISA, transient transfection, western blotting (WB), immunoprecipitation, and immunofluorescence staining (IF). Chemical-induced autophagy was examined by WB, IF, and RNAi.
  
  
  RESULTS
  RC, MM, and RD reduced the viability of LNCaP cells accompanied with arrested cell cycle in the G0/G1 phase and induction of apoptosis. Further investigation revealed that these compounds significantly inhibited AR expression at mRNA and protein levels, leading to the suppression of AR transcriptional activity. Moreover, inhibition of proteasome activity by bisbibenzyls, which in turn caused the induction of autophagy, as noted by induction of LC3B expression, conversion, and accumulation of punctate dots in treated cells. Co-localization of AR/LC3B and AR/Ub suggested that autophagy contributed to the degradation of polyubiquitinated-AR when proteasome activity was suppressed by the bisbibenzyls.
  
  
  CONCLUSIONS
  Suppression of proteasome activity and induction of autophagy were involved in bisbibenzyl-mediated modulation of AR activities and apoptosis, suggesting their potential in treating PCa.
authors.affiliation: a Department of Biochemistry and Molecular Biology , Shandong University School of Medicine , Jinan , China .
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Hu
authors.affiliation: a Department of Biochemistry and Molecular Biology , Shandong University School of Medicine , Jinan , China .
authors.forename: Denglu
authors.initials: D
authors.lastname: Zhang
authors.affiliation: a Department of Biochemistry and Molecular Biology , Shandong University School of Medicine , Jinan , China .
authors.forename: Dawei
authors.initials: D
authors.lastname: Wang
authors.affiliation: b Department of Natural Product Chemistry , Shandong University School of Pharmaceutical Sciences , Jinan , China , and.
authors.forename: Bin
authors.initials: B
authors.lastname: Sun
authors.affiliation: a Department of Biochemistry and Molecular Biology , Shandong University School of Medicine , Jinan , China .
authors.forename: Ayesha
authors.initials: A
authors.lastname: Safoor
authors.affiliation: c Department of Urology , Mayo Clinic College of Medicine, Mayo Clinic , Rochester , MN , USA.
authors.forename: Charles Y F
authors.initials: CY
authors.lastname: Young
authors.affiliation: b Department of Natural Product Chemistry , Shandong University School of Pharmaceutical Sciences , Jinan , China , and.
authors.forename: Hongxiang
authors.initials: H
authors.lastname: Lou
authors.affiliation: a Department of Biochemistry and Molecular Biology , Shandong University School of Medicine , Jinan , China .
authors.forename: Huiqing
authors.initials: H
authors.lastname: Yuan
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000302:isolation & purification / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D001632:Bibenzyls / Q000302:isolation & purification / Q000494:pharmacology*; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004988:Ethers, Cyclic / Q000302:isolation & purification / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D035926:Hepatophyta / Q000737:chemistry; D006801:Humans; D008297:Male; D010647:Phenyl Ethers / Q000302:isolation & purification / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology; D061988:Proteasome Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D021381:Protein Transport / Q000187:drug effects; D011944:Receptors, Androgen / Q000235:genetics* / Q000378:metabolism; D013267:Stilbenes / Q000302:isolation & purification / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D001632:Bibenzyls; D004988:Ethers, Cyclic; D010647:Phenyl Ethers; D061988:Proteasome Inhibitors; D011944:Receptors, Androgen; D013267:Stilbenes; C584935:marchantin M; C505660:riccardin C; C547185:riccardin D
keywords: Androgen receptor; bisbibenzyls; prostate cancer; proteasome