Abstract
BackgroundAs one of the most frequent chemical modifications in eukaryotic mRNAs, N6-methyladenosine (m6A) modification exerts important effects on mRNA stability, splicing, and translation. Recently, the regulatory role of m6A in tumorigenesis has been increasingly recognized. However, dysregulation of m6A and its functions in tumor epithelial-mesenchymal transition (EMT) and metastasis remain obscure.MethodsqRT-PCR and immunohistochemistry were used to evaluate the expression of methyltransferase-like 3 (METTL3) in gastric cancer (GC). The effects of METTL3 on GC metastasis were investigated through in vitro and in vivo assays. The mechanism of METTL3 action was explored through transcriptome-sequencing, m6A-sequencing, m6A methylated RNA immunoprecipitation quantitative reverse transcription polymerase chain reaction (MeRIP qRT-PCR), confocal immunofluorescent assay, luciferase reporter assay, co-immunoprecipitation, RNA immunoprecipitation and chromatin immunoprecipitation assay.ResultsHere, we show that METTL3, a major RNA N6-adenosine methyltransferase, was upregulated in GC. Clinically, elevated METTL3 level was predictive of poor prognosis. Functionally, we found that METTL3 was required for the EMT process in vitro and for metastasis in vivo. Mechanistically, we unveiled the METTL3-mediated m6A modification profile in GC cells for the first time and identified zinc finger MYM-type containing 1 (ZMYM1) as a bona fide m6A target of METTL3. The m6A modification of ZMYM1 mRNA by METTL3 enhanced its stability relying on the “reader” protein HuR (also known as ELAVL1) dependent pathway. In addition, ZMYM1 bound to and mediated the repression of E-cadherin promoter by recruiting the CtBP/LSD1/CoREST complex, thus facilitating the EMT program and metastasis.ConclusionsCollectively, our findings indicate the critical role of m6A modification in GC and uncover METTL3/ZMYM1/E-cadherin signaling as a potential therapeutic target in anti-metastatic strategy against GC.
Highlights
As one of the most frequent chemical modifications in eukaryotic mRNAs, N6-methyladenosine (m6A) modification exerts important effects on mRNA stability, splicing, and translation
methyltransferase-like 3 (METTL3) overexpression and its prognostic value in gastric cancer (GC) To explore the expression of the major m6A-modifying enzymes in GC, we first queried the published clinical data sets TCGA (The Cancer Genome Atlas) and GSE66229, and found that METTL3 mRNA expression was significantly elevated in GC tissues compared to that in normal tissues
METTL3 promoted GC cell invasion and metastasis in vitro and in vivo To assess whether METTL3-mediated epithelial-mesenchymal transition (EMT) was responsible for GC metastasis, we explored the effects of METTL3 on cell motility
Summary
As one of the most frequent chemical modifications in eukaryotic mRNAs, N6-methyladenosine (m6A) modification exerts important effects on mRNA stability, splicing, and translation. As the most prevalent internal chemical modification of RNAs in eukaryotes, N6-methyladenosine (m6A) modification is a reversible process which is mediated by the m6A methyltransferases methyltransferase-like 3 (METTL3), methyltransferase-like 14 (METTL14), and Wilms tumor 1 associated protein (WTAP) and eliminated by fat-mass and obesity-associated protein (FTO) or alkylation repair homolog protein 5 (ALKBH5) [8,9,10,11]. In mammals, this modification influences different aspects of RNA metabolism, resulting in mRNA stability and splicing [12, 13], translation efficiency [14], nuclear export [15], alternative polyadenylation [16], as well as microRNA processing [17]. The definite role of m6A in GC remains unclear, and dysregulation of m6A in the EMT process and metastasis has never been studied
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
