Differential effects of estrogen and estrogen receptor antagonist, ⅡCI 182780 on the expression of Calbindin-D9k in rat pituitary prolactinoma GH3 cells / 中华内分泌外科杂志

ABSTRACT

Objective To detect the effects of 17 β-estradiol(E2)on the expression of Calbindin-D9k (CaBP-9k) in pituitary GH3 cells,and to investigate the antagonistic effect of a selective estrogen receptor antagonist,ⅡCI 182780 on CaBP-9k expression.Methods A rat pituitary prolactinoma cell line,GH3 cell was used as the in vitro model.The localization of CaBP-9k in GH3 cells was observed by immunofluorescence.GH3 cells were cultured with exogenous E2-added medium for 24 hours,and the concentrations of E2 were 10-8,10-9,10-10M,respectively.mRNA and protein expression levels of CaBP-9k in different groups were analyzed by RT-PCR and Western blot analysis.The estrogen receptor antagonist,and ⅡCI 182780 was added to GH3 cells before E2 administration (10-8M)with the concentration of 10-6M,in order to investigate the regulation of ER-mediated pathway on the expression of CaBP-9k.Immunoprecipitation was used to detect the interaction between CaBP-9k and ERα.Results E2 had significant stimulatory effect on the CaBP-9k expression of GH3 cells in a dose dependent manner,and the expression level of CaBP-9k was higher when treated with a higher concentration of E2.ⅡCI 182780 could suppress the stimulatory effect of E2 on the CaBP-9k expression of GH3 cells.The expression level of CaBP-9k was significantly reduced by coadministration of E2 with ⅡCI 182780 in GH3 cells,which meant the CaBP-9k expression was mediated through ERα pathway.The immunoprecipitation results further illustrated the fact that CaBP-9k could directly interact with ERα,and E2 could increase the interaction between CaBP-9k and ERα.Conclusion Estrogen might induce CaBP-9k expression via ERα mediated pathway and CaBP-9k could directly combine with ERα,suggesting that CaBP-9k might be involved in the biological effects mediated by ER pathway in GH3 cells.