FOXL2 Knockdown Inhibits the Progression of Endometriosis

PROBLEM: Endometriosis (EM) is known as a common estrogen-dependent chronic inflammatory disease. Elevated levels of Forkhead box L2 (FOXL2) have been observed in uterine diseases, including EM. However, the molecular mechanism of FOXL2 in EM needs to be further illustrated. This study aimed to investigate the regulatory role of FOXL2 in EM rats and isolated ectopic endometrial stromal cells (EC-ESCs). METHOD OF STUDY: FOXL2 knockdown were designed to evaluate the effects of FOXL2 in EM model rats and EC-ESCs. Hematoxylin-eosin (HE) staining was used to evaluate the pathological morphology of ectopic endometrium. Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) analysis and immunohistochemistry (IHC) were applied to detect the expression of FOXL2, EM-related genes, and epithelial to mesenchymal transition-related proteins. The proliferation, migration, invasion, and apoptosis of EC-ESCs were determined by 5-ethynyl-2'-deoxyuridine (EDU) assay, Transwell assay, and flow cytometry. RESULTS: The FOXL2 level was remarkably higher in the ectopic endometrial tissue than that in the normal endometrial tissue. Knockdown of FOXL2 notably improved the pathological morphology of EM in rats, and decreased expression levels of ER-α, ER-ß, and Cyp19a. Additionally, down-regulation of FOXL2 suppressed cells proliferation, migration and invasion, and stimulated more apoptotic cells in EC-ESCs. Besides, FOXL2-small interfering RNA (FOXL2-siRNA) treatment resulted in enhanced cleaved-Caspase3 protein expression and cleaved-Caspase3/Caspase3 ratio in EC-ESCs. CONCLUSION: FOXL2 participates in the occurrence and development of EM through promoting epithelial-mesenchymal transition procession and enhancing the migration and invasion of EC-ESCs, suggesting that FOXL2 may be a new therapeutic target for the EM therapy.