METTL3-mediated m(6)A modification of lncRNA SNHG3 accelerates gastric cancer progression by modulating miR-186-5p/cyclinD2 axis

OBJECTIVES: METTL3 as an m(6)A methyltransferase acts in diverse malignancies including gastric cancer (GC). We aimed to reveal the underlying mechanisms by which METTL3 contributes to gastric carcinogenesis. METHODS: The association of METTL3 and SNHG3 with GC was analyzed by qRT-PCR, Western blot, and TCGA cohort. The functional experiments were implemented to uncover the role of METTL3 in GC. m(6)A dot blot and MeRIP were used to determine METTL3-mediated m(6)A modification of lncRNA SNHG3. The effect of METTL3 on SNHG3-mediated miR-186-5p/cyclinD2 axis was evaluated by luciferase gene report, RT-qPCR, and Western blot assays. RESULTS: We found that METTL3 was remarkably elevated in GC tissues and correlated with poor survival in patients with GC. Silencing of METTL3 impaired GC cell growth and invasion, whereas restored METTL3 expression promoted these effects. Mechanistically, reduced expression of METTL3 decreased SNHG3 m(6)A level and caused a decrease in SNHG3 expression, which could further act as a sponge of miR-186-5p to upregulate cyclinD2. Overexpression of SNHG3 attenuated METTL3 knockdown-induced anti-proliferating and miR-186-5p upregulation and cyclinD2 downregulation. CONCLUSION: We find that METTL3-mediated m(6)A modification of lncRNA SNHG3 accelerates GC progression by modulating miR-186-5p/cyclinD2 axis.