Breast cancer cells can recognize and respond to different levels of progestins to achieve different phenotypic outputs [RNA-seq]

The steroid hormone progesterone, acting through its nuclear progesterone receptor (PR), has complex physiologic activities with different levels of hormones manifesting distinct and sometimes opposing phenotypic responses in target tissues. However, most of what is currently known about the transcriptional activity of PR comes from studies performed using progestins at levels that are in the high physiologic range (>10nM), relevant only in the luteal phase of the reproductive cycle and pregnancy in humans. These studies do not consider the non-linearity of responses to progestins that exist in physiology and are not informative as to the mechanisms by which low levels of progestins, as occurs during menopause (0.1-0.3nM), exert their biological activities. Thus, we undertook to define the mechanisms which enable cells to recognize and respond to different levels of progestins.