title: Differential effects of estrogen and estrogen receptor antagonist, ICI 182 780, on the expression of calbindin-D9k in rat pituitary prolactinoma GH₃ cells.
abstract: OBJECTIVE
  To detect the effects of 17β-estradiol (E2) on the expression of calbindin-D9k (CaBP-9k) in pituitary GH3 cells, and to determine the antagonistic effect of a selective estrogen receptor (ER) antagonist (ICI 182 780) on CaBP-9k expression.
  
  
  METHODS
  A rat pituitary prolactinoma cell line (GH3 cells) was used in an in vitro model. The localization of CaBP-9k in GH3 cells was observed by immunofluorescence. GH3 cells were cultured with the addition of E2 medium for 24 hours. The levels of CaBP-9k mRNA and protein expression in different groups were analyzed by RT-PCR and Western blot analysis. The ER antagonist, ICI 182 780, was added to GH3 cells before E2 (10(-8) M) at a concentration of 10(-6) M to investigate the regulation of an ER-mediated pathway on CaBP-9k expression.
  
  
  RESULTS
  E2 had a stimulatory effect on CaBP-9k expression of GH3 cells in a dose-dependent manner; the level of CaBP-9k expression was higher when treated with a higher concentration of E2. ICI 182 780 suppressed the stimulatory effect of E2 on CaBP-9k expression in GH3 cells. The level of CaBP-9k expression was significantly reduced by co-administration of E2 with ICI 182 780 in GH3 cells. The immunoprecipitation results confirmed that CaBP-9k interacts directly with ERα, and E2 increases the interaction between CaBP-9k and ERα.
  
  
  CONCLUSIONS
  Estrogen induces CaBP-9k expression via an ERα-mediated pathway and CaBP-9k directly combines with ERα, suggesting that CaBP-9k is involved in the biological effects mediated by an ER pathway in GH3 cells.
authors: Department of Breast Surgery, China-Japan Union Hospital, Jilin University 126 Xiantai Blvd, Changchun 130033, P.R. China.
authors: Wan
authors: W
authors: Wang
authors: Department of Neurosurgery, Medical University of Vienna Waehringer Guertel 18-20, Vienna 1090, Austria.
authors: Engelbert
authors: E
authors: Knosp
authors: Department of Immunology, College of Basic Medical Science, Jilin University 126 Xinmin Street, Changchun 130021, P.R. China.
authors: Guixiang
authors: G
authors: Tai
authors: Department of Neurosurgery, China-Japan Union Hospital, Jilin University 126 Xiantai Blvd, Changchun 130033, P.R. China.
authors: Yuanzheng
authors: Y
authors: Zhao
authors: Department of Neurosurgery, China-Japan Union Hospital, Jilin University 126 Xiantai Blvd, Changchun 130033, P.R. China.
authors: Qianlei
authors: Q
authors: Liang
authors: Department of Neurosurgery, China-Japan Union Hospital, Jilin University 126 Xiantai Blvd, Changchun 130033, P.R. China.
authors: Yongchuan
authors: Y
authors: Guo
mesh_terms: D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D065171:Estrogen Receptor Antagonists / Q000494:pharmacology*; D005455:Fluorescent Antibody Technique; D000077267:Fulvestrant; D047468:Immunoprecipitation; D010911:Pituitary Neoplasms / Q000378:metabolism*; D015175:Prolactinoma / Q000378:metabolism*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D064030:S100 Calcium Binding Protein G / Q000096:biosynthesis*
chemical_list: D065171:Estrogen Receptor Antagonists; D064030:S100 Calcium Binding Protein G; D000077267:Fulvestrant; D004958:Estradiol
keywords: CaBP-9k; GH3 cells; ICI 182 780; estrogen; estrogen receptor