Progesterone is critical to regulation of the menstrual cycle, is involved in the physiology of many organs such as bone, mammary glands, and nervous system, and has been implicated in the etiology of breast cancer (Kolatorova et al. Int J Mol Sci, 2022). This 21-carbon steroid hormone is synthesized primarily in the ovaries and in the placenta during pregnancy, with lower levels produced in other tissues such as the adrenal cortex and testes (Sundström-Poromaa et al. Front Neuroendocrinol, 2020). Progesterone binds to progesterone receptors (PR) A and B, through which it impacts gene regulation and signaling pathway activation.

Progesterone has been used for:

MAINTENANCE AND SELF-RENEWAL
· Induce expansion of mouse mammary stem cells (Asselin-Labat et al. Nature, 2010; Joshi et al. Nature, 2010).
DIFFERENTIATION
· Induce expression of Elf5 transcription factor resulting in well-developed ductal side-branching (Lee et al. Development, 2013).
CANCER RESEARCH
· Induce high grade serous carcinoma with metastatic potential in a mouse model (Kim et al. Proc Natl Acad Sci U S A, 2020).
· Promote cell growth of triple-negative breast cancer (TNBC) cells and increase tumor size in a TNBC mouse model (An et al. Proc Natl Acad Sci U S A, 2022).
· Inhibit cell migration and invasion of human breast cancer cell lines (Godbole et al. Cell Oncol, 2017).