Plant Estrogens: Effects on Cell Cycle Progression in Breast Cancer Cells
Abstract
We investigated the cellular uptake of genistein by p53-deficient T47 cells and the effects of genistein on redox status and cell cycle progression as well as signaling pathways. Cell-associated levels of genistein and metabolite in T47D breast cancer cells at 2 and 24 hours were increased. In comparison with other dietary flavanoids, cell-associated levels of genistein were relatively higher in breast cancer cells treated with genistein (5-50 mM). This metabolite was also present in the medium at both 2 and 24 hours, thus suggesting that genistein is taken up into the cells where it is metabolized and extruded into the media. Genistein treatment resulted in an 80% decrease in intracellular GSH levels. Changes in redox cellular status can influence signaling pathways. Indeed, redox-sensitive protein STAT3, which controls the cell cycle inhibitor, p21, was upregulated in response to genistein treatment. Furthermore, there was an inhibition of cell proliferation and G2 cell cycle arrest, which was further supported by a downregulation of cdc-2 expression and cdc2 kinase activity. Genistein modulated mitochondrial-linked apoptotic protein. This included the upregulation Bcl-2 and Bcl-x, Apaf-1 (apoptotic protease activating factor), caspase 9, and procaspase 3, which resulted in DNA fragmentation. These results suggest that genistein is taken up into cells where it causes STAT3 and p21 upregulation, G2 cell cycle arrest, with subsequent inhibition of cell proliferation and induction of apoptosis. Collectively, these data show that genistein can elicit an antiproliferative effect via a p53-independent mechanism.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2002
- Accession Number
- ADA406272
Entities
People
- Enrique Cadenas
Organizations
- University of Southern California