Prostaglandin E2 receptor EP1 in healthy and diseased human endometrium.

Prostaglandin E2 (PGE2) is well described to be associated with both endometrial functions and disorders. The primary aim of this study was to explore the underlying mechanisms that affect the growth and function of endometrial epithelium and stroma by assessing the staining intensity of PGE2 receptors (EP) in healthy endometrium across the menstrual cycle and in pathological endometrium, such as ovarian endometriosis and endometrial cancer. We retrospectively analyzed the EPs staining intensity in human nonpregnant endometrium throughout the menstrual cycle by immunohistochemistry and further focused on EP1 (n = 42). The variation of EP1 was compared among healthy endometrium, ovarian endometriosis (n = 14), and endometrial cancer (n = 140) crosswise. EP1 presented cyclical changes with increased intensity in both epithelium and stroma during the proliferative phase. EP1 staining in the epithelium was increased in endometriotic tissue compared to healthy endometrium and tumor tissue, while in the stroma, the staining in the tumor was lower than that in both normal tissue and endometriosis. No significant differences in EP1 intensity were detected for histological, stage, grading, metastatic and recurrent subtypes in endometrial cancer. EP1 was also correlated with neither progression-free survival nor overall survival of patients with cancer. EP1 staining in progesterone receptor B (PRB)-positive tumor was stronger compared to PRB-negative tumor. EP1 may play a role in human endometrial physiology and pathology. Further studies on the effect of EP1 on human endometrium are needed.

The relationship between prostaglandin E receptor 1 and cyclooxygenase I expression in guinea pig bladder interstitial cells: proposition of a signal propagation system.

PURPOSE: We explored the structural relationship between enzymes producing prostaglandin (cyclooxygenase I) and 1 of the receptor families that respond to prostaglandin (prostaglandin E receptor 1) in the bladder muscle. MATERIALS AND METHODS: Nine male guinea pigs were sacrificed by cervical dislocation. Bladders were removed and fixed in 4% paraformaldehyde in phosphate buffered saline. Frozen sections (10 µm) were cut and stained with antibodies to prostaglandin E receptor type 1, cyclooxygenase I and vimentin. RESULTS: Prostaglandin E receptors 1 was identified on smooth muscle cells, and vimentin positive surface muscle and intramuscular interstitial cells. Muscle staining was less intense than on interstitial cells and had a punctuate appearance. Prostaglandin E receptor 1 expression on interstitial cells was highly localized. Discrete regions of intense staining were noted on interstitial cell processes. Cyclooxygenase I was also expressed in muscle interstitial cells. Cyclooxygenase I positive interstitial cells were more prevalent in the muscle bundles of the inner muscle than in the outer muscle layers. Cyclooxygenase I staining was noted on discrete regions of the cell or cell processes. Double staining with prostaglandin E receptor 1 and cyclooxygenase I suggested that cell regions expressing the former are different from those expressing the latter. CONCLUSIONS: The discovered arrangement of prostaglandin E receptor 1 and cyclooxygenase I may have the potential to facilitate the propagation of signals in the interstitial cell network. Such a signaling system may have a role in coordinating events, as in bladder pathology, facilitating the global coordinated changes associated with bladder wall remodeling.