Non-genomic actions of progesterone in the normal and neoplastic mammalian ovary

This review summarizes recent findings on the non-genomic or membrane-initiated actions of progesterone that regulate the function of the normal and neoplastic mammalian ovary. This review focuses on three receptors: the classic progesterone receptor, the membrane progesterone receptors (MPR alpha, beta, and gamma) that were initially cloned from seatrout ovaries, and a progesterone binding protein referred to as progesterone receptor membrane component-1 (PGRMC1). Specifically, the structure of each of these receptors is compared and related to their capacity to activate various signal transduction pathways. Then the biological effects of P4 on the function of granulosa cells, luteal cells, ovarian surface epithelial cells, and ovarian cancers that are derived from the ovarian surface epithelial cells are discussed in relationship to the expression of each of these receptors. Whenever possible, studies involving human cells and tissues are presented, although data from other mammalian species are used to supplement the human studies to provide a more complete picture of this complex and rapidly developing area of membrane-initiated actions of progesterone.