METTL14 Promotes Proliferation, Migration, and Invasion in Endometriotic Stromal Cell Growth by Activating the ZEB1/MEK/ERK Pathway.

Objective: The aim of this study was to explore the mechanism of methyltransferase-like 14 (METTL14) on human endometriotic stromal cell (ESC; HEM15A) proliferation, migration, and invasion to provide novel therapy for endometriosis (EMs).

Design: Normal human endometrial stromal cells (HESCs) and HEM15A cells were selected. Corresponding controlled experiments were performed to analyze whether overexpression of METTL14, N6-methyladenosine (m6A) methylated ZEB1 mRNA, upregulation of ZEB1, and activating the mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) can affect the proliferation, migration, and invasion of HEM15A cells. Materials, Setting, and Methods: HEM15A and HESCs were cultured in vitro. HEM15A cells were treated with oe-METTL14 and oe-zinc finger E-box-binding protein 1 (ZEB1) plasmids, 3-deazaadenosine (3-DAA) and the MEK/ERK pathway inhibitor isoprenaline (ISO). After identifying HEM15A and HESCs, METTL14, ZEB1, p-ERK1/2/ERK1/2, and p-MEK/MEK levels, and cell proliferation, migration, and invasion were assessed. The modification sites of ZEB1 and m6A were predicted using SRAMP database, with an m6A modification level assessed by MeRIP. The binding of YT521-B homology domain 2 (YTHDF2) to ZEB1 messenger RNA (mRNA), and ZEB1 stability and mRNA level were tested.

Results: Compared with HESCs, METTL14 level in HEM15A was significantly reduced. METTL14 overexpression in HEM15A prominently increased its proliferation, migration, and invasion. METTL14 overexpression notably elevated m6A-methylated ZEB1 mRNA level and reduced the stability and expression of ZEB1 mRNA. Further m6A modification inhibition increased ZEB1 mRNA stability and mRNA and protein levels and decreased ZEB1 m6A modification level. ZEB1 upregulation partially reversed METTL14 overexpression-inhibited HEM15A proliferation, migration, and invasion. METTL14 inhibited the MEK/ERK signaling activation by regulating ZEB1, and the MEK/ERK signaling activation partly averted METTL14-suppressed proliferation, migration, and invasion.

Limitations: The effects of METTL14 on other growth aspects of HEM15A cells and the relation between ZEB1 and m6A require further investigation.

Conclusions: METTL14 lowered ZEB1 expression by regulating ZEB1 m6A modification levels, thereby inhibiting the activation of the MEK/ERK pathway and ESC proliferation, migration, and invasion.