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AGENCY USE ONLY (Leave blank)2. REPORT DATE January 2 001
REPORT TYPE AND DATES COVEREDFinal (15 Jul 96 -31 Dec 00)
TITLE AND SUBTITLE
Control of the Mammary Cell Cycle Clock by Estrogen and Progesterone
AUTHOR(S)Robert A. Weinberg, Ph.D. Both the growth and the development of the mammary gland are controlled by the female hormones estrogen, prolactin and progesterone, and by interactions between the epithelial and stromal compartments of the breast. Changes in the regulation of any of these processes may lead to breast cancer. We have investigated the role of progesterone in the process of sidebranching and alveologenesis in the mammary gland using mice lacking the progesterone receptor which are defective in these processes. By reconstituting murine mammary glands in vivo, we have shown that the progesterone receptor is required only in epithelial cells for proper sidebranching and alveologenesis to occur. Our studies indicate that progesterone acts in a paracrine manner and suggest that Wnt-4 is a mediator of the paracrine signals released from progesterone receptor-positive cells. In addition, we have characterized the role of the estrogen receptor (ER) in regulating the proliferation of breast cancer cells. We postulate that the ability of ER to control cyclin Dl expression and proliferation of breast cancer cells may be acquired during breast cancer progression. This is indicated by the fact that ectopic expression of the estrogen receptor in human epithelial cells does not, on its own, enable signaling between the ER and the cyclin Dl gene. Moreover, others have demonstrated that the ER-positive cells in the mammary epithelium are distinguishable from those that are actively mitotic. Finally, our work indicates that the effects of deletion of the prolactin receptor (PrlR) from mammary epithelial cells closely phenocopy the consequences of deleting cyclin Dl from these cells. We suggest that activation of the PrlR by its ligand results in the production of jnsuliJl-like growth factor-2 which in turn induces cyclin Dl synthesis in these cells^ ; - Conclusions 8
FUNDING NUMBERS
DAMD17-96-1-6285
PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Whitehead
SUBJECT TERMS
Breast CancerReferences 9Appendices 10Final Report Laboratory of Robert A. Weinberg Ph.D.DAMD 17-96-1-6285Our research performed under the auspices of the Army Breast Cancer grant has focused on the ab...