Effects of 12-O-tetradecanoylphorbol-13-acetate on estrogen receptor activity in MCF-7 cells.
Effects of 12-O-tetradecanoylphorbol-13-acetate on estrogen receptor activity in MCF-7 cells.
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12-O-tetradecanoylphorbol-13-acetate 对 MCF-7 细胞中雌激素受体活性的影响。
DOI：
10.1074/jbc.270.42.25244
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Saceda,M
中科院分区：
文献类型：
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作者：
Martin,MB;Garcia-Morales,P;Stoica,A;Solomon,HB;Pierce,M;Katz,D;Zhang,S;Danielsen,M;Saceda,M
研究了12-O-十四酰佛波醇-13-乙酸酯(TPA)长期作用对人乳腺癌细胞株MCF-7雌激素受体(ER)表达的影响。这项研究表明，佛波酯处理细胞阻断了雌激素受体的活性。100 nM TPA处理细胞后，ER蛋白水平下降80%，ER mRNA和结合量同时下降。从培养液中去除TPA后，ER蛋白和mRNA水平恢复到对照水平；然而，受体不能与雌二醇结合。这些细胞也不能诱导孕激素受体对雌二醇的反应。此外，TPA处理在瞬时转染法中阻止了雌激素反应元件的转录，并在DNA迁移率改变分析中抑制了ER与其反应元件的结合。处理细胞中的雌激素受体可被两种抗ER的单抗识别，并且与对照细胞中的ER在数量上没有差别。核糖核酸酶保护分析未能检测到ER mRNA转录本的任何质变。混合实验表明，TPA诱导/激活了一种与ER相互作用的因子，以阻断雌二醇的结合。TPA对ER水平和结合容量的影响呈浓度依赖性。低浓度的TPA抑制雌激素结合而不降低蛋白质水平，而较高浓度的TPA则需要降低ER蛋白质水平。TPA的作用似乎是通过激活蛋白激酶C来实现的，因为蛋白激酶C抑制剂H-7和Bryostatin可以阻断TPA对雌二醇孕酮受体的诱导作用。TPA治疗对糖皮质激素受体的水平或结合能力没有影响，表明这种作用对类固醇受体并不普遍。这些数据表明，蛋白激酶C信号转导通路的激活调节雌激素受体通路。蛋白激酶C激活的长期效应是通过诱导/激活一种与雌激素受体相互作用的因子来抑制雌激素受体的功能。
The effects of long term treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) on estrogen receptor (ER) expression in the human breast cancer cell line, MCF-7, were studied. This study demonstrates that treatment of cells with the phorbol ester blocked estrogen receptor activity. Treatment of cells with 100 nM TPA resulted in an 80% decrease in the level of ER protein and a parallel decrease in ER mRNA and binding capacity. Following removal of TPA from the medium, the level of ER protein and mRNA returned to control values; however, the receptor failed to bind estradiol. These cells also failed to induce progesterone receptor in response to estradiol. In addition, TPA treatment blocked transcription from an estrogen response element in transient transfection assays and inhibited ER binding to its response element in a DNA mobility shift assay. The estrogen receptor in treated cells was recognized by two monoclonal anti-ER antibodies and was not quantitatively different from ER in control cells. RNase protection analysis failed to detect any qualitative changes in the ER mRNA transcript. Mixing experiments suggest that TPA induces/activates a factor which interacts with the ER to block binding of estradiol. The effects of TPA on ER levels and binding capacity were concentration-dependent. Low concentrations of TPA inhibited estradiol binding without a decrease in the level of protein, whereas higher concentrations were required to decrease the level of ER protein. The effects of TPA appear to be mediated by activation of protein kinase C since the protein kinase C inhibitors, H-7 and bryostatin, block the effects of TPA on estradiol induction of progesterone receptor. TPA treatment had no effect on the level or binding capacity of the glucocorticoid receptor, indicating that the effects are not universal for steroid receptors. These data demonstrate that activation of the protein kinase C signal transduction pathway modulates the estrogen receptor pathway. The long term effect of protein kinase C activation is to inhibit estrogen receptor function through induction/activation of a factor which interacts with the receptor.