METTL3/YTHDF2 m6A axis promotes the malignant progression of bladder cancer by epigenetically suppressing RRAS.

The present study aimed to explore the potential roles of the methyltransferase­like 3 (METTL3)­mediated methylation of RAS related (RRAS) mRNA in the tumorigenesis and development of bladder cancer (BCa). For this purpose, the relative expression levels of METTL3 in BCa specimens and cell lines were measured using reverse transcription­quantitative PCR (RT­qPCR) and western blot analysis. The association between the METTL3 expression level and the clinical characteristics of patients with BCa was analyzed using The Cancer Genome Atlas (TCGA) and Gene Expression Profiling Interactive Analysis databases. Cellular experiments were performed to confirm the effects of METTL3 on the proliferative, migratory and invasive capacities of BCa cells. RT­qPCR, western blot analysis, methylated RNA immunoprecipitation (MeRIP)­qPCR and dual­luciferase report assays were utilized to verify the METTL3/RRAS/YTH N6­methyladenosine (m6A) RNA binding protein 2 (YTHDF2) regulatory axis in BCa. The results revealed that METTL3 expression was markedly increased in BCa specimens and cell lines, and was associated with poor clinical characteristics of patients with BCa. In vitro and in vivo assays demonstrated that the silencing of METTL3 markedly suppressed the proliferative, migratory and invasive capacities of BCa cells. MeRIP­PCR and dual­luciferase report assays indicated that METTL3 could bind to the m6A sites of RRAS mRNA and suppress the transcriptional activity of RRAS. YTHDF2 could recognize the m6A sites of RRAS and mediate RRAS degradation. On the whole, the findings of the present study reveal the pivotal role of METTL3­catalyzed m6A modification in BCa tumorigenesis and development. The change could facilitate BCa tumor growth and metastasis by suppressing RRAS expression in an m6A YTHDF2­dependent manner. Targeting the METTL3/RRAS/YTHDF2 regulatory axis may thus prove to be a promising strategy for the diagnosis and therapy of BCa.