雌激素通过其受体α上调LRP16 mRNA表达并促进MCF-7细胞增殖

Estrogen stimulates human breast cancer MCF-7 cell proliferation by up-regulation of LRP16 mRNA via activation of estrogen receptor-α

目的 探讨雌激素对人乳腺癌MCF 7细胞LRP16mRNA表达的调控作用以及过表达LRP16对MCF 7细胞生长特性的影响。方法 ( 1)用Northern印迹方法检测 17β 雌二醇 ( 17β E2 )对LRP16mRNA表达水平的作用 ;( 2 )构建LRP16启动子 ( -2 .6kb)调控的荧光素酶报告子 ( pGL3 S0 ) ,并与各种核受体包括雌激素受体α和 β(ERα和ERβ)、糖皮质激素受体α(GRα)、雄激素受体 (AR)和过氧化物酶体增殖物激活的受体γ和α(PPARγ和PPARα)表达载体共转染COS 7细胞 ,测定荧光素酶活性 ;( 3 )将LRP16表达载体转染MCF 7细胞 ,测定过表达LRP16对细胞的生长特性和细胞周期的影响 ,并用Western印迹方法测定周期素E、p5 3和 p2 1WAF1/CIP1蛋白的变化。结果 ( 1) 17β E2 使MCF 7细胞的LRP16mRNA表达水平增加 5～ 8倍 ,增加幅度未显示出 β E2 培养时间和剂量的依赖性 ;( 2 ) pGL3 S0 与ERα或AR共转染细胞的相对荧光素酶活性较单独转染 pGL3 S0 细胞 (对照组 )分别升高 11和 7.8倍 ;( 3 )LRP16过表达促进MCF 7细胞的生长且伴有周期素E显著升高 ,S期细胞的数量较对照组增加约 10 %。结论 ( 1)雌激素通过激活ERα增加MCF 7细胞LRP16mRNA的表达 ;( 2 )过表达LRP16可能通过上调周期素E促进MCF 7细胞生长。

Objective To investigate the effect of estrogen on the expression of LRP16 mRNA in human breast cancer MCF-7 cells and the effects of overexpression of LRP16 on MCF-7 cell proliferation and differentiation. Methods (1) The expression level of LRP16 mRNA induced by 17β-estradiol (17β-E 2) was determined by Northern blot. (2) LRP16 promoter-controlled luciferase expression vector (pGL3-S 0) was constructed and was co-transfected with various nuclear receptors, including estrogen receptor α and β (ERα and ERβ), glucocorticoid receptor α (GRα), androgen receptor (AR) and peroxisome-proliferator activated receptor γ and α (PPARγ and PPARα), into COS-7 cells, then the relative luciferase activity was measured with Dual-Luciferase Report Assay 1000 Systems. (3) After LRP16 expression vector was transfected into MCF-7 cells, the effect of overexpression of LRP16 on MCF-7 proliferation was examined by trypan blue exclusion method, and the cell cycle was analyzed by flow cytometry. The expression levels of cyclin E, p53 and p21 WAF1/CIP1proteins were determined by Western blot. Results (1) 17β-E 2 induced 5- to 8-fold increase of LRP16 mRNA in MCF-7 cells, and this effect did not show time- and dose-dependence; (2) The relative luciferase activities in the COS-7 cells co-transfected by pGL3-S 0 and ERα or AR were 11-fold and 7.8-fold, respectively, of the control cells transfected by pGL3-S 0 alone and (3) Overexpression of LRP16 stimulated MCF-7 cell proliferation with increased cyclin E and the cell number in S-phase increased about 10% as compared with the control. Conclusion Estrogen up-regulates the expression level of LRP16 mRNA through activation of ERα; overexpression of LRP16 stimulates MCF-7 cell proliferation via increment of cyclin E.