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Updated: Jun 27, 2026

An Ex vivo Model to Study Hormone Action in the Human Breast
Published on: January 8, 2015
Progesterone and breast cancer
1University of Minnesota, Cancer Center, Department of Medicine (Hematology, Oncology & Transplantation), 420 Delaware Street SE, MMC 806, MN 55455, USA. lange047@umn.edu
Abstract:
Progesterone is an ovarian steroid hormone that is essential for normal breast development during puberty and in preparation for lactation and breastfeeding. The actions of progesterone are primarily mediated by its high-affinity receptors, which include the classical progesterone receptor (PR)-A and -B isoforms, located in diverse tissues, including the brain, where progesterone controls reproductive behavior, and the breast and reproductive organs. Progestins are frequently prescribed for contraception or during postmenopausal hormone replacement therapy, in which progestins are combined with estrogen as a means to block estrogen-induced endometrial growth. The role of estrogen as a potent breast mitogen is undisputed, and inhibitors of the estrogen receptor and estrogen-producing enzymes (aromatases) are effective first-line cancer therapies. However, PR action in breast cancer is grossly understudied and remains controversial. Herein, we review existing evidence and discuss the challenges to defining a role for progesterone in breast cancer.
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