Activation of bone morphogenetic protein-6 gene transcription in MCF-7 cells by estrogen
- Author:
Ming ZHANG
1
;
Ji-Dong YAN
;
Lei HANG
;
Qing WANG
;
Shu-Jun L(U)
;
Jie ZHANG
;
Tian-Hui ZHU
Author Information
1. 南开大学
- Keywords:
bone morphogenetic protein-6;
estrogen;
chromatin immunoprecipitation;
site-directed mutagenesis
- From:
Chinese Medical Journal
2005;(19):1629-1636
- CountryChina
- Language:Chinese
-
Abstract:
Background Bone morphogenetic protein-6 (BMP-6) is closely correlated with tumor differentiation and skeletal metastasis. Estrogen is considered as a stimulant for the initiation and promotion of breast cancer. Previous studies demonstrated that 17β-estadiol (E2) can selectively increase the expression of BMP-6. This experiment is designed to detect the molecular mechanism of estrogen activating BMP-6 gene transcription in human estrogen receptor positive (ER+) breast cancer cell line MCF-7. Methods After the treatment of MCF-7 cells with E2 at different concentrations (10-11 mol/L, 10-9 mol/L, 10-7 mol/L), the BMP-6 expression level was examined through real-time polymerase chain reaction. Through restriction enzyme digestion, human BMP-6 1.2 kb long promoter, BMP-6 0.7 kb long promoter was cloned into pGL-3 basic vector; after the treatment with 10-7 mol/L E2, luciferase activities of the two promoters were detected. Site-directed mutagenesis was performed to obtain the mutant forms of estrogen response element half-site (1/2 ERE) element and Sp1 sites in the BMP-6 promoter, the activities of these mutant form promoters were detected following the methods mentioned above. Chromatin immunoprecipitation (ChIP) assay was also used to confirm the binding of estrogen receptor α (Erα) on BMP-6 promoter in the presence of E2. Results E2 dose dependently increased BMP-6 mRNA expression in human ER+ breast cancer cell line MCF-7. At a dose of 10-7 mol/L E2, human BMP-6 1.2 kb promoter activity was increased by 90% compared with the control group treated with ethanol (P<0.05). Both the 1/2 ERE response element mutant form and the Sp1 site mutant form of the BMP-6 promoter abolished the activation of the BMP-6 promoter's response to E2. Through ChIP assay, the binding of Erα on 1/2 ERE response element in BMP-6 promoter was further validated. Conclusion Estrogen induces BMP-6 expression in human ER+ breast cancer cell line MCF-7 through its receptor Erα binding on 1/2 ERE element in the BMP-6 promoter.
