人乳腺癌细胞系MCF-7细胞中糖皮质激素受体的表达及其调节

Regulation of glucocorticoid receptor expression by dexamethasone in a human breast cancer cell line MCF-7

目的研究地塞米松(Dex)在MCF-7细胞中是否具有糖皮质激素受体(GR)的表达,以及Dex对其受体表达的调节。方法采用氨基安替比林法测定GR拮抗剂(RU486)作用MCF-7细胞后能否阻断糖皮质激素的效应,采用放射配体结合分析法检测MCF-7细胞中GR的表达及Dex对其调节作用。结果 RU486可完全阻断Dex对MCF-7细胞活性的诱导作用;在细胞中存在高亲和力、低容量GR;Dex明显降低GR结合活性,且具有时间、剂量依赖性。结论在MCF-7细胞中存在GR,Dex调节MCF-7细胞增殖分化的作用通过 GR介导,Dex对MCF-7细胞GR的结合活性具有向下调节作用,且呈时间、剂量依赖性。

Objective To clarify the mechanism of action of dexamethasone on proliferation of human breast carcinoma cell line MCF-7; and the expression and the regulation of glucocorticoid receptor（GR） in MCF-7 cells by dexamethasone. Methods The expression and regulation of GR in MCF-7 cells was studied utilizing radioligand- binding assay. Results The induction of AKP activity by dexamethasone was blunted by RU486, a potent glu cocorticoid antagonist. There existed high affinity and low capacity of GR in MCF-7 cells, the GR binding activity could be down-regulated by dexamethasone in a time-and dose dependent manner. Conclusions The functional GR in MCF-7 cells and the cellular effect of dexamethasone on MCF-7 cells are mediated by GR while GR can be downregulated by dexamethasone.