Osteopontin and Its Receptor αvβ3 Integrin Are Coexpressed in the Human Endometrium during the Menstrual Cycle But Regulated Differentially

Osteopontin is an arginine-glycine-aspartic acid-containing acidic glycoprotein component of the extracellular matrix that is postulated to bind to integrin receptors at the cell surface to mediate cellular adhesion and migration during embryo implantation. The primary aim of this study was to examine the uterine expression of osteopontin throughout the menstrual cycle in normal fertile controls sampled prospectively based on urinary LH surge detection. Expression of osteopontin was documented using Northern blot analysis, in situ hybridization, and immunohistochemistry. Furthermore, the temporal pattern of osteopontin expression was compared with that of its receptor, the αvβ3 integrin. Using Ishikawa cells, a well differentiated endometrial adenocarcinoma cell line, the in vitro regulation of osteopontin and its receptor αvβ3 integrin was studied. By Northern blot analysis, osteopontin mRNA appears during the early secretory phase, with maximal expression occurring in mid to late secretory-phase endomet...