Identification of Cytoplasmic Proteins Interacting with the Mammary Cell Transforming Domain of Ese-1
Annual rept. 29 Mar 2007-29 Mar 2008
COLORADO UNIV HEALTH SCIENCES CENTER AURORA CO
Pagination or Media Count:
ETS factors comprise a large transcription factor family known to play a significant role in cellular development, differentiation, and transformation. Emerging evidence reveals that increased mRNA expression of the human Ets factor-1, ESE-1, is associated with breast cancer. Stable expression of ESE-1 transforms MCF-12A immortalized human mammary epithelial cells. However, little is known about ESE-1 protein expression and its role in maintaining the transformed phenotype in human breast cancer cell lines. Here, we used an anti- ESE-1 mouse monoclonal antibody in Western blot and immunofluorescent cell analyses to show that ESE-1 is expressed as a nuclear protein in MCF-7, T47D and ZR-75 transformed, tumorigenic mammary epithelial cell lines, and that it is not expressed in transformed MDAMB- 231 and nontransformed MCF-10A and MCF-12A cells. In addition, specific knockdown of endogenous ESE-1 in the human breast carcinoma ZR-75 and MCF-7 cell lines decreased colony formation and anchorage independent growth. Mechanistically, ESE-1 knockdown decreased cellular proliferation, but had no effect on apoptosis. Finally, serum withdrawal resulted in a time-dependent, 90 reduction of ESE-1 protein production in MCF-7 cells. These results establish that ESE-1 plays a key role in maintaining the transformed phenotype in breast cancer, thus providing a novel single-point target for breast cancer therapy.
- Medicine and Medical Research