MECHANISM OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN (TCDD)-MEDIATED DECREASE OF THE NUCLEAR ESTROGEN-RECEPTOR IN MCF-7 HUMAN BREAST-CANCER CELLS

被引:74
作者
WANG, X [1 ]
PORTER, W [1 ]
KRISHNAN, V [1 ]
NARASIMHAN, TR [1 ]
SAFE, S [1 ]
机构
[1] TEXAS A&M UNIV SYST,DEPT VET PHYSIOL & PHARMACOL,COLL STN,TX 77843
关键词
TCDD; ARYL HYDROCARBON RECEPTOR; ER DOWN-REGULATION; MECHANISM;
D O I
10.1016/0303-7207(93)90106-T
中图分类号
Q2 [细胞生物学];
学科分类号
071009 ; 090102 ;
摘要
Treatment of MCF-7 cells with 1 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 1 nM [H-3]17beta-estradiol resulted in decreased radiolabeled nuclear estrogen receptor (ER) levels as determined by velocity sedimentation analysis. In parallel studies, nuclear extracts from TCDD-treated cells also exhibited decreased binding to a consensus P-32-genomic estrogen responsive element (ERE) as determined in a gel mobility shift assay. Time-course studies showed that the decreases in nuclear ER and ER-ERE binding in TCDD-treated cells were observed within 1 to 3 h after treatment, respectively, and persisted for up to 24 h. Cycloheximide (10 muM) did not affect the TCDD-mediated response, whereas 1 muM alpha-naphthoflavone, an aryl hydrocarbon (Ah) receptor antagonist, partially blocked downregulation of nuclear ER binding by TCDD. TCDD did not significantly affect steady state ER mRNA levels as determined by Northern analysis or the rate of ER gene transcription in a nuclear run-on assay. These results suggest that the TCDD-mediated decrease in nuclear ER levels is an Ah receptor-mediated response which occurs at the translational or post-translational level.
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页码:159 / 166
页数:8
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