Cell Cycle Regulatory Roles of ER-Alpha in Breast Cancer
Abstract
The roles of estrogen and estrogen receptor (ER) in normal mammary gland development and in transformation to a tumor phenotype have been extensively studied. However, although the cumulative data suggests an important role for ER in breast cancer, the function of ER in regulating cell proliferation in normal and tumor tissue remains unclear. This study investigates the role of ER-alpha on the progression of the cells through different phases of the cell cycle in the presence and absence of its ligand, estradiol. The cellular localization of ER-alpha is also examined during cell cycle transition in MCF-7 cells. Experimental Design: The ER negative MDA-MB 231 and ER positive MCF-7 cell lines were used for study. Cells were synchronized in G1 phase of the cell cycle with lovastatin for 36 hours in estrogen free media and subsequently released from arrest with mevalonate. Transient transfection of MDA MB 231 cells with ER-alpha as well as addition of 17- estradiol to the cells were performed at the time of release from cell cycle arrest. Cells were harvested at different time intervals (0-68 hrs) after the release and subjected to western blot and flow cytometry analysis. For immunofluorescent detection of ER-alpha MCF-7 cells cultured on coverslips, synchronized with lovastatin and stained with anti-ER alpha antibody. Cells stained to look at ER-alpha in the cell. Results: Synchronization of MCF-7 cells revealed that the endogenous ER is subject to cell cycle regulation with its levels peaking at the S/G2 phase of the cell cycle. Similarly, MDA-MB231 cells transiently transfected with ER-alpha demonstrate tight cell cycle periodicity similar to that seen with cyclin B. Specifically, ER-alpha is up-regulated during late S phase and early G2 phase, and is down regulated during late G2 and M phases. In contrast, in non-synchronized MDA-MB 231 cells, exogenously transfected,
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2007
- Accession Number
- ADA471166
Entities
People
- Sonia Kamrani
Organizations
- The University of Texas MD Anderson Cancer Center