PGRMC1 promotes progestin-dependent proliferation of breast cancer cells by binding prohibitins resulting in activation of ERα signaling

Combined menopausal hormone therapy is associated with increased breast cancer risk in postmenopausal women. In our previous studies, progesterone receptor membrane component 1 (PGRMC1) was shown to play a role in progestins’ mode of action, resulting in enhanced proliferation of breast cancer cells. Here we describe a potential mechanism by which PGRMC1 contributes to breast cancer progression via interaction with prohibitins, inhibiting their function as transcription factor repressors, thereby facilitating estrogen receptor alpha (ERα) transcriptional activity and enhancing oncogenic signaling upon treatment with certain progestins, such as norethisterone and dydrogesterone.