Epithelial cell protein milk fat globule epidermal growth factor 8 and human chorionic gonadotropin regulate stromal cell apoptosis in the human endometrium
Milk fat globule–epidermal growth factor 8, a multifunctional epithelial protein in the human endometrium, and hCG modulate apoptosis of stromal cells.
Ryan M. Riggs, M.D., Silvina Bocca, M.D., Ph.D., Sandra Anderson, B.S., Anahi Franchi, Ph.D., Bhaskara S. Rhavi, M.Sc., Sergio Oehninger, M.D., Ph.D.
Volume 98, Issue 6, Pages 1549-1556.e3, December 2012
To study the regulation of apoptosis in human endometrial cells. The specific aims were: 1) to determine if MFG-E8, a novel endometrial epithelial protein, modulates caspase activation and DNA fragmentation; and 2) to examine if hCG, an early embryonic product, regulates Bax and Bcl-2 equilibrium, as well as MFG-E8 expression.
Primary cultures of human endometrial epithelial (EEC) and stromal (ESC) cells.
Ovulatory women aged 21-30 years.
Treatment with MFG-E8 and hCG.
Main Outcome Measure(s):
Apoptotic activity was quantified using a luciferase assay. DNA fragmentation was detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-fluorescein nick-end labeling assay (TUNEL). Bax, Bcl-2 and MFG-E8 mRNA expression levels were determined by qRT-PCR. Immunocytochemistry was used to establish cell purity and presence of MFG-E8 and hCG-R (receptor) proteins.
EEC were cytokeratin+, vimentin-, MFG-E8+, and hCG-R+ whereas ESC were vimentin+, cytokeratin-, MFG-E8- and hCG-R+. MFG-E8 treatment of ESC resulted in a 13-fold increase in caspase activity and a 30-fold increase in TUNEL. On the other hand, hCG decreased mRNA expression of Bax in ESC.
Milk fat globule–epidermal growth factor 8 has proapoptotic activity, suggesting participation in endometrial remodeling via an epithelial–stromal cell paracrine effect. Conversely, pregnancy levels of hCG has opposite effects on stromal cells.