METTL3 stabilizes SERPINE2 via the m6A modification to drive the malignant progression of gastric signet ring cell carcinoma.

Background: Gastric signet ring cell carcinoma (GSRCC) is a highly lethal malignancy. Serpin family E member 2 (SERPINE2) is a pro-tumorigenic factor in cancer. Here, we sought to define the role of SERPINE2 in the pathogenesis of GSRCC.

Methods: Messenger RNA (mRNA) expression was analyzed by quantitative polymerase chain reaction (PCR). Protein expression was tested by immunohistochemistry (IHC) and immunoblot assays. Proliferation was assessed by 5-ethynyl-2'-deoxyuridine (EdU) assay, and invasion and migration were detected by transwell assay. Tube formation assay was used to test the influence on angiogenesis. Cell apoptosis and M2 macrophage polarization were evaluated by flow cytometry. The methyltransferase-like 3 (METTL3)-SERPINE2 relationship was analyzed by RNA immunoprecipitation (RIP), luciferase, and mRNA stabilization assays. Xenograft experiments were used for assessment of METTL3's influence on tumorigenicity of GSRCC cells.

Results: SERPINE2 and METTL3 levels were upregulated in human GSRCC. Functionally, SERPINE2 depletion enhanced apoptosis of GSRCC cells and diminished their proliferative, migratory and invasive capacities in vitro. Moreover, SERPINE2 depletion suppressed tube formation ability of human umbilical vein endothelial cells (HUVECs) and M2 polarization of THP-1-derived macrophages. Mechanistically, METTL3 induced SERPINE2 upregulation by enhancing SERPINE2 mRNA stabilization. Our rescue experiments indicated that the effects of METTL3 depletion on cell phenotypes were due to the reduction of SERPINE2 expression. Additionally, METTL3 deficiency inhibited GSRCC xenograft growth in vivo.

Conclusions: Our study defines the significant roles of the METTL3/SERPINE2 axis as an epigenetic mechanism in GSRCC progression. Our work may have diagnostic and/or therapeutic applications in GSRCC.