Wormke M, Castro-Rivera E, Chen I, Safe S
Department of Veterinary Physiology and Pharmacology, Texas A & M University, TX 77843-4466, College Station, USA.
J Steroid Biochem Mol Biol. 2000 Apr;72(5):197-207. doi: 10.1016/s0960-0760(00)00030-3.
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.
石川子宫内膜癌细胞表达雌激素受体（ER），本研究调查了该细胞系中芳烃受体（AhR）的表达以及AhR与ER之间的抑制性相互作用。用AhR激动剂[3H]2,3,7,8-四氯二苯并对二恶英（TCDD）处理石川细胞，得到一种在蔗糖密度梯度中沉降系数为6.0 S的放射性标记核复合物，蛋白质印迹分析证实石川细胞表达人AhR和AhR核转运蛋白（Arnt）。用10 nM TCDD处理石川细胞，在转染了含有Ah反应性人CYP1A1基因启动子插入片段（-1142至+2434）的pRNH11c的细胞中，CYP1A1依赖性乙氧基异吩恶唑酮O-脱乙基酶（EROD）活性增加了9.7倍，氯霉素乙酰转移酶（CAT）活性增加了10.5倍。在石川细胞中，使用雌激素（E2）诱导的细胞增殖和转录激活试验，对转染了含有孕激素受体和卵黄蛋白原A2基因启动子插入片段的E2反应性构建体的细胞进行抑制性AhR-ER相互作用研究。包括TCDD、苯并[a]芘（BaP）和6-甲基-1,3,8-三氯二苯并呋喃在内的AhR激动剂抑制了32%-47%的E2诱导反应。相比之下，雌激素和孕激素均未抑制TCDD在石川细胞中诱导的EROD活性，而在ECC-1子宫内膜细胞中观察到抑制性ER-AhR相互作用，这表明这些相互作用依赖于细胞环境。
