title: Dexamethasone suppresses DU145 cell proliferation and cell cycle through inhibition of the extracellular signal-regulated kinase 1/2 pathway and cyclin D1 expression.
abstract: OBJECTIVE
  To determine the mechanisms of glucocorticoids in inhibiting advanced prostate cancer growth.
  
  
  METHODS
  The cell proliferation and cell cycle of prostate cancer DU145 cells following dexamethasone treatment were determined by proliferation assay and fluorescence-activated cell sorter. Western blot analysis was carried out to evaluate the effects of dexamethasone on phosphorylation of extracellular signal-regulated kinase (ERK)1/2 and expression of cyclin D1 in DU145 cells with or without glucocorticoid receptor (GR) antagonist RU486. Reverse transcription-polymerase chain reaction verified the expression of GR mRNA in DU145 cells.
  
  
  RESULTS
  Dexamethasone significantly inhibited DU145 cell proliferation at the G(0)/G(1) phase. Western blot analysis showed a dramatic reduction of ERK1/2 activity and cyclin D1 expression in dexamethasone-treated cells. The decreased phosphorylation of ERK1/2 in dexamethasone-treated cells was attenuated by GR blockade. Additionally, the effects of dexamethasone in inhibiting cyclin D1 expression were altered by GR blockade.
  
  
  CONCLUSIONS
  Dexamethasone suppresses DU145 cell proliferation and cell cycle, and the underlying mechanisms are through the inhibition of phosphorylation of ERK1/2 and cyclin D1 expression. The inhibition of ERK1/2 phosphorylation and cyclin D1 expression is attenuated by GR blockade, suggesting that GR regulates ERK1/2 and cyclin D1 pathways. These observations suggest that dexamethasone has a potential clinical application in prostate cancer therapy.
authors: Friendship Nephrology Center and Blood Purification Center, Jinan City Central Hospital, Shandong University School of Medicine, Jinan, China.
authors: Qing-Zhen
authors: QZ
authors: Gao
authors: Jia-Ju
authors: JJ
authors: Lu
authors: Zi-Dong
authors: ZD
authors: Liu
authors: Hui
authors: H
authors: Zhang
authors: Shao-Mei
authors: SM
authors: Wang
authors: He
authors: H
authors: Xu
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D019938:Cyclin D1 / Q000187:drug effects / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D018931:Antineoplastic Agents, Hormonal; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D019938:Cyclin D1; D003907:Dexamethasone; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3