Ree A H, Landmark B F, Eskild W, Levy F O, Lahooti H, Jahnsen T, Aakvaag A, Hansson V
Institute of Medical Biochemistry, University of Oslo, Norway.
Endocrinology. 1989 May;124(5):2577-83. doi: 10.1210/endo-124-5-2577.
In the present study we have examined the effects of estradiol on mRNA levels for estrogen (ER) and progesterone receptors (PR) in the estrogen-dependent mammary carcinoma MCF-7 cell line. The changes in ER immunoactivity and specific binding of [3H]R5020 were also assessed. Estradiol (10(-7) M) caused a transient and time-dependent reduction of the level of mRNA for ER, with a maximal effect (30-40% of control; n = 3) after 72 h. This was associated with a similar decrease in ER immunoactivity. Further treatment (96 and 120 h) revealed a return of ER mRNA to control values, whereas the ER immunoactivity remained depressed. The effect on the mRNA level for PR gave almost the inverse curve. Initially (24-72 h), we observed a pronounced increase in this mRNA, with a maximal effect (6-7 times the control value; n = 3) after 72 h. Treatment beyond 72 h was associated with a gradual return of mRNA for PR toward the control level. The variation in specific binding of [3H]R5020 revealed similar changes, except that changes in specific receptor binding were delayed 24 h compared to the levels of mRNA. Incubation with low concentrations (10(-11) and 10(-10) M) of estradiol for 72 h was associated with slightly elevated levels of mRNA for ER, whereas higher concentrations gave a dose-dependent decrease. The mRNA for PR was biphasically stimulated, with a maximal effect at 10(-10)-10(-8) M, where a 10- to 13-fold stimulation was observed. The highest concentration (10(-7) M) gave a lower response. Assessment of concentration-induced variations in protein receptor levels of ER and PR reflected the effects of estradiol on their mRNAs. Low concentrations of estradiol slightly enhanced the ER level, whereas high concentrations clearly reduced ER immunoactivity. The PR level was stimulated by all concentrations used, and 10(-8) M estradiol raised the PR level more than 11-fold. Our results indicate autologous regulation of estrogen receptor gene transcripts and proteins and a clear induction of PR mRNA and receptor proteins by estradiol.
在本研究中，我们检测了雌二醇对雌激素依赖性乳腺癌MCF - 7细胞系中雌激素受体（ER）和孕激素受体（PR）mRNA水平的影响。还评估了ER免疫活性和[3H]R5020特异性结合的变化。雌二醇（10(-7) M）导致ER mRNA水平出现短暂的、时间依赖性降低，72小时后达到最大效应（为对照的30 - 40%；n = 3）。这与ER免疫活性的类似降低相关。进一步处理（96和120小时）显示ER mRNA恢复到对照值，而ER免疫活性仍处于较低水平。对PR mRNA水平的影响几乎呈现相反的曲线。最初（24 - 72小时），我们观察到该mRNA显著增加，72小时后达到最大效应（为对照值的6 - 7倍；n = 3）。72小时后继续处理导致PR mRNA逐渐恢复到对照水平。[3H]R5020特异性结合的变化显示出类似变化，但特异性受体结合的变化比mRNA水平延迟24小时。用低浓度（10(-11)和10(-10) M）的雌二醇孵育72小时与ER mRNA水平略有升高相关，而较高浓度则导致剂量依赖性降低。PR mRNA受到双相刺激，在10(-10) - 10(-8) M时达到最大效应，观察到10至13倍的刺激。最高浓度（10(-7) M）产生较低的反应。对ER和PR蛋白受体水平浓度诱导变化的评估反映了雌二醇对其mRNA的影响。低浓度的雌二醇略微提高ER水平，而高浓度则明显降低ER免疫活性。所有使用的浓度均刺激PR水平，10(-8) M的雌二醇使PR水平提高超过11倍。我们的结果表明雌激素受体基因转录本和蛋白的自身调节以及雌二醇对PR mRNA和受体蛋白的明显诱导作用。
