Roles of the insulinlike growth factor family in nonpregnant human endometrium and at the Decidual: Trophoblast interface

The insulinlike growth factor (IGF) family is believed to be important in e ndometrial development during the menstrual cycle and in the process of imp lantation. The mitogenic, differentiative, and antiapoptotic properties of the IGFs and their binding proteins, as well as their spatial and temporal expression in cycling endometrium, suggest that they may participate in end ometrial growth, differentiation, apoptosis, and perhaps angiogenesis. IGFB P proteases, which increase IGF bioavailability, have been localized to end ometrial stromal cells and to the human cytotrophoblast and likely play imp ortant roles in endometrial decidual, and trophoblast physiology. IGFBP-1 i s a major protein product of nonpregnant endometrium during the mid-late se cretory phase and occurs in abundance in decidua. Its roles as an IGF-bindi ng protein and as a trophoblast integrin ligand suggest that it may have mu ltiple roles in endometrial development and in interactions between the dec idua and the invading trophoblast. Recent evidence suggests that it may hav e a role in the process of shallow implantation in the clinical disorder of preclampsia. In contrast to knowledge about the roles of IGF peptides, IGF BP proteases, and IGFBPs in normal endometrial development and early human pregnancy, little information is available regarding this family in abnorma l endometrial development, in occult endometrial defects, and in uterine re ceptivity and nonreceptivity.