Estrogen and aryl hydrocarbon receptor expression and crosstalk in human Ishikawa endometrial cancer cells.
Ishikawa endometrial cancer cells express the estrogen receptor (ER), and this study investigates aryl hydrocarbon receptor (AhR) expression and inhibitory AhR-ER crosstalk in this cell line. Treatment of Ishikawa cells with the AhR agonist [3H]2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) gave a radiolabeled nuclear complex that sedimented at 6.0 S in sucrose density gradients, and Western blot analysis confirmed that Ishikawa cells expressed human AhR and AhR nuclear translocator (Arnt) proteins. Treatment of Ishikawa cells with 10 nM TCDD induced a 9.7-fold increase in CYP1A1-dependent ethoxyresorufin O-deethylase (EROD) activity and a 10.5-fold increase in chloramphenicol acetyltransferase (CAT) activity in cells transfected with pRNH11c containing an Ah-responsive human CYP1A1 gene promoter insert (-1142 to +2434). Inhibitory AhR-ER crosstalk was investigated in Ishikawa cells using E2-induced cell proliferation and transcriptional activation assays in cells transfected with E2-responsive constructs containing promoter inserts from the progesterone receptor and vitellogenin A2 genes. AhR agonists including TCDD, benzo[a]pyrene (BaP) and 6-methyl-1,3,8-trichlorodibenzofuran, inhibited 32-47% of the E2-induced responses. In contrast, neither estrogen nor progesterone inhibited EROD activity induced by TCDD in Ishikawa cells, whereas inhibitory ER-AhR crosstalk was observed in ECC-1 endometrial cells suggesting that these interactions were cell context-dependent.
Wormke
M
M
Department of Veterinary Physiology and Pharmacology, Texas A & M University, TX 77843-4466, College Station, USA.
Castro-Rivera
E
E
Chen
I
I
Safe
S
S
D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D001564:Benzo(a)pyrene / Q000494:pharmacology; D001572:Benzofurans / Q000494:pharmacology; D015500:Chloramphenicol O-Acetyltransferase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D019363:Cytochrome P-450 CYP1A1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D016889:Endometrial Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006801:Humans; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000187:drug effects / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
C497396:ARNT protein, human; D001572:Benzofurans; D004268:DNA-Binding Proteins; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D014157:Transcription Factors; C054923:6-methyl-1,3,8-trichlorodibenzofuran; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D001564:Benzo(a)pyrene; D004958:Estradiol; D019363:Cytochrome P-450 CYP1A1; D015500:Chloramphenicol O-Acetyltransferase