YTHDF2 is a novel diagnostic marker of endometrial adenocarcinoma and endometrial atypical hyperplasia/ intraepithelial neoplasia.

Numerous studies show that some biomarkers are aberrantly expressed in endometrial endometrioid adenocarcinoma (EMAC) and endometrial atypical hyperplasia/endometrioid intraepithelial neoplasia (EAH/EIN) compared to endometrial benign lesions. Because of low sensitivity and/or specificity, the utility of these markers to distinguish EMAC and EAH/EIN from benign endometrial lesions is limited. YTH domain family 2 (YTHDF2) is a functional N6-methyladenosine (m6A)-specific reader protein that mainly regulates mRNA stability. Aberrant YTHDF2 expression has been reported in many cancers and plays important functions in tumorigenesis and cancer progression. However, its expression in endometrial benign and malignant lesions has not been investigated. We evaluated YTHDF2 mRNA and protein expression in EMAC and normal endometrium using the UALCAN database and validated the bioinformatic results in EMAC cells using qRT-PCR, Western blot, and immunohistochemical (IHC) staining. We found that YTHDF2 was weakly expressed in normal endometrium, benign endometrial lesions, endometrial hyperplasia without atypia, and adenomyosis. In contrast, YTHDF2 was upregulated in EAH/EIN and EMAC. These results indicate that YTHDF2 immunostaining may be a useful tool to distinguish EAH/EIN from EHWA. Finally, YTHDF2 expression can accurately assess the depth of myometrial invasion (DMI) in EMAC when EMAC coexists with adenomyosis.