title: Just when you thought it was safe to go into the membrane: the growing complexities of extra-nuclear progesterone signaling.
abstract: The diversity of membrane-initiated progesterone actions has made characterization and establishment of its biological importance a complicated endeavor. A new study by Zuo and colleagues shows that progesterone via endogenous membrane progesterone receptor-alpha acts as a negative regulator of proliferation and epithelial to mesenchymal transition in a breast cancer cell line. These progesterone-mediated actions appear to be regulated through epidermal growth factor receptor and phosphatidylinositol 3-kinase signaling localized in caveolae. Moreover, the study shows expression of membrane progesterone receptor-alpha in benign and malignant breast cancer tissues. These data bring forth novel concepts with regard to progesterone actions in the breast; however, further work is warranted to fully characterize the physiologic actions of extra-nuclear progesterone signaling in the breast.
authors.forename: Aritro
authors.initials: A
authors.lastname: Sen
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Hammes
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D008648:Mesoderm / Q000378:metabolism* / Q000473:pathology; D011374:Progesterone / Q000502:physiology*; D011372:Progestins / Q000502:physiology; D011980:Receptors, Progesterone / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D011372:Progestins; D011980:Receptors, Progesterone; D011374:Progesterone