Mesenchymal epithelial transformation is involved in the formation of cysts in endometriosis rats

Objective To investigate the role of stromal epithelial transformation and Snail in ectopic cyst formation in endometriosis (EMS) rats. Methods The model of EMS rats was established by autologous transplantation. EMS rats were successfully divided into 2-7 weeks after modeling. The normal rats were taken as the normal control group. Immunohistochemical method was used to study the localization and expression of epithelial marker (E-cadherin, cytokeratin 8), mesenchymal marker (vimentin) and Snail in ectopic endometrial cysts. Western blotting was performed to detect the expression of E-cadherin and vimentin in endometriotic cyst. TUNEL method was used to detect the apoptosis of exfoliated cells in ectopic cyst. Results Immunohistochemistry showed that the EMS rat model of endometriotic cyst cavity epithelial E-cadherin, cytokeratin 8 and vimentin in the model after 2-7 weeks in the process, relative to the cyst wall stroma are at a high level, but compared with the normal endometrial epithelium, also at a higher level. In addition, 2-7 weeks ectopic cyst epithelial cell shedding, positive expression of E-cadherin, cytokeratin 8 and vimentin, and 4-5 weeks after modeling, the positive signal was the strongest. Compared with normal rat endometrial tissue, Snail positive expression signal was enhanced in the ectopic endometrium cyst cavity epithelium 3-5 weeks after modeling. The Western blotting result showed that the content of E-cadherin and vimentin in the ectopic endometrium after 2-7 weeks was significantly higher than that in the normal endometrium, and the difference was statistically significant (P<0.05). TUNEL assay showed no apoptosis in the exfoliated cells of ectopic cysts. Conclusions The epithelial cells in ectopic cystic cavity of EMS model rats may be formed by the transformation of mesenchymal cells, suggesting that the mesenchymal epithelial transformation is involved in the formation of ectopic cysts, Snail regulates MET development, and epithelial cells in the ectopic endometrium cyst cavity are detached. The formation of a cavity constitutes an ectopic endometrial cyst of an EMS model rat, and epithelial cells shedding to form a cyst without involvement of apoptosis. Key words: Endometriosis (EMS); Rats; Autologous transplantation models; Stromal epithelial transformation; Cysts