2,3,7,8-四氯二苯并对二恶英、12-O-十四酰佛波醇-13-乙酸酯和17β-雌二醇对MCF-7人乳腺癌细胞雌激素受体调节的影响。

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin, 12-O-tetradecanoylphorbol-13-acetate and 17 beta-estradiol on estrogen receptor regulation in MCF-7 human breast cancer cells.

作者信息

Gierthy J F, Spink B C, Figge H L, Pentecost B T, Spink D C

机构信息

Wadsworth Center, New York State Department of Health, Albany 12201-0509, USA.

出版信息

J Cell Biochem. 1996 Feb;60(2):173-84. doi: 10.1002/(sici)1097-4644(19960201)60:2<173::aid-jcb2>3.0.co;2-u.

DOI:10.1002/(sici)1097-4644(19960201)60:2<173::aid-jcb2>3.0.co;2-u

PMID:8655628

Abstract

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exhibits remarkably potent antiestrogenic activity. To further elucidate the role of estrogen receptor (ER) regulation in this response, we examined the effects of exposure to TCDD in MCF-7 human breast cancer cells on ER mRNA levels by using an RNase protection assay, on ER accumulation by using an ER immunocytochemical essay (ER-ICA), and on ER function by competitive binding assays under conditions of saturating 17 beta-estradiol (E2). Comparative studies were conducted with E2 and 12-O-tetradecanoylphorbol-13-acetate (TPA), as both compounds are known to suppress ER expression. Our results indicate that 1 nM E2 and 100 nM TPA both suppress ER mRNA levels as early as 4 h after exposure and to 33.6% and 16.5% of control levels, respectively, after 72 h. In contrast, no significant effect on ER mRNA levels was attributed to exposure to 10 nM TCDD. A greater than 50% reduction in positive staining was observed by ER-ICA after 72 h exposure to 1 nM E2 and to 100 nM TPA, while only an 11% reduction in positive staining was observed with 10 nM TCDD. Specific binding of [3H]E2 under saturating conditions (10 nM E2) in whole cells was reduced by 50% in cultures exposed to 100 nM TPA, although no effect on binding was observed with exposure to 10 nM TCDD. In contrast, specific binding using subsaturating 1 nM [3H]E2 was depressed by 49% in MCF-7 cells exposed to 10 nM TCDD for 72 h. This depression was inhibited by a 1-h treatment with 5 microM alpha-naphthoflavone, which inhibits TCDD-induced, P450-mediated, E2 metabolism, and subsequent E2 depletion. In conclusion, while TPA and E2 effectively down-regulate ER expression, TCDD, under antiestrogenic conditions, has little if any effect on total ER levels in MCF-7 cells, and thus ER modulation is probably not necessary for the suppression of estrogenic activity in MCF-7 cells by TCDD.

摘要

2,3,7,8-四氯二苯并-对-二恶英（TCDD）具有显著的抗雌激素活性。为了进一步阐明雌激素受体（ER）调节在此反应中的作用，我们通过核糖核酸酶保护试验检测了MCF-7人乳腺癌细胞暴露于TCDD对ER mRNA水平的影响，通过ER免疫细胞化学分析（ER-ICA）检测了对ER积累的影响，并在饱和17β-雌二醇（E2）条件下通过竞争性结合试验检测了对ER功能的影响。用E2和12-O-十四酰佛波醇-13-乙酸酯（TPA）进行了比较研究，因为已知这两种化合物都会抑制ER表达。我们的结果表明，1 nM E2和100 nM TPA在暴露后4小时就开始抑制ER mRNA水平，72小时后分别降至对照水平的33.6%和16.5%。相比之下，暴露于10 nM TCDD对ER mRNA水平没有显著影响。在暴露于1 nM E2和100 nM TPA 72小时后，通过ER-ICA观察到阳性染色减少了50%以上，而在10 nM TCDD处理下仅观察到阳性染色减少了11%。在饱和条件（10 nM E2）下，全细胞中[3H]E2的特异性结合在暴露于100 nM TPA的培养物中减少了50%，尽管暴露于10 nM TCDD时未观察到对结合的影响。相比之下，在暴露于10 nM TCDD 72小时的MCF-7细胞中，使用亚饱和1 nM [3H]E2的特异性结合降低了49%。用5 microM α-萘黄酮处理1小时可抑制这种降低，α-萘黄酮可抑制TCDD诱导的、细胞色素P450介导的E2代谢以及随后的E2耗竭。总之，虽然TPA和E2能有效下调ER表达，但在抗雌激素条件下，TCDD对MCF-7细胞中的总ER水平几乎没有影响，因此ER调节可能不是TCDD抑制MCF-7细胞雌激素活性所必需的。