METTL3 is aberrantly expressed in endometriosis and suppresses proliferation, invasion, and migration of endometrial stromal cells.

Endometriosis (EM) is one of the leading gynecological disorders, and associated with excessive functioning of endometrial stromal cells (ESCs). The current study was conducted to determine the expression and role of methyltransferase-like 3 (METTL3) in the proliferation, invasion, and migration of ESCs in EM. The documented expression levels of METTL3, microRNA (miR)-21-5p, and WNT inhibitory factor 1 (WIF1) in eutopic (Eut) and ectopic (Ect) endometrial tissues and ESCs were determined by a combination of real-time quantitative polymerase chain reaction and Western blot assay. After transfection with pcDNA3.1-METTL3, miR-21-5p mimic, and WIF1 small interfering RNA, cell counting kit-8, colony formation, and Transwell assays were performed in the Ect ESCs (Ect-ESCs). Subsequently, the binding of miR-21-5p to METTL3 was analyzed, along with quantification of the N6-methyladenosine (m6A) level, the enrichments of METTL3 and m6A on WIF1, and the mRNA stability of WIF1. In our findings, METTL3 was downregulated in the EM tissues and cells. METTL3 overexpression intrinsically reduced the proliferation, invasion, and migration of Ect-ESCs. miR-21-5p inhibited the METTL3 expression while METTL3 enhanced the mRNA stability and expression of WIF1 via m6A modification. Additionally, a negative correlation of METTL3 was identified with miR-21-5p along with a positive correlation with the WIF1 mRNA in EM tissues. The miR-21-5p overexpression or WIF1 downregulation enhanced the proliferation, invasion, and migration of Ect-ESCs. Collectively, miR-21-5p inhibited the METTL3-mediated m6A modification and mRNA stability of WIF1, thereby facilitating the proliferation, invasion, and migration of Ect-ESCs.