In: Progesterone9 Feb 2013
The second important function of estrogen in vivo may be to stimulate the production of growth factors whose synthesis is not required when they are added to the culture system. We have shown that proliferating stromal cells in culture express a single form of fibroblast growth factor receptor-1, demonstrating the potential of these cells to respond to added bFGF. Addition of suramin to stromal cell cultures containing bFGF and progesterone significantly inhibited proliferation, indicating that exogenous bFGF was able to activate its receptor. In the ovariectomized rat uterus, bFGF steady-state mRNA levels increase in response to estrogen and progesterone. Stromal cells in culture do not proliferate in response to progesterone alone, suggesting either that an insufficient amount of bFGF is produced in these cells or that the mechanisms for exporting bFGF in cultured stromal cells are altered. buy flovent inhaler
Steroid hormones act as transcription factors; thus it is likely that cell cycle genes are one of the targets for progesterone action. Estrogen and progesterone stimulate the expression of c-fos, c-jun, and c-myc in breast cancer cells, and the magnitude of the response is similar to that obtained when transcription of these genes is stimulated by growth factors. In breast cancer cell lines, cyclin D1 is responsive to both estrogen and progesterone. However, the response to progesterone is of greater magnitude. Preliminary results in our laboratory indicate that cyclin D1 mRNA is one target for progesterone receptor in quiescent uterine stromal cells stimulated to proliferate with progesterone and bFGF (unpublished results).
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