RETRACTED ARTICLE: RNA m6A methylation regulates the epithelial mesenchymal transition of cancer cells and translation of Snail

Abstract

N6 -Methyladenosine (m 6 A) modification has been implicated in the progression of several cancers. We reveal that during epithelial-mesenchymal transition (EMT), one important step for cancer cell metastasis, m 6 A modification of mRNAs increases in cancer cells. Deletion of methyltransferase-like 3 (METTL3) down-regulates m 6 A, impairs the migration, invasion and EMT of cancer cells both in vitro and in vivo. m 6 A-sequencing and functional studies confirm that Snail, a key transcription factor of EMT, is involved in m 6 A-regulated EMT. m 6 A in Snail CDS, but not 3’UTR, triggers polysome-mediated translation of Snail mRNA in cancer cells. Loss and gain functional studies confirm that YTHDF1 mediates m 6 A-increased translation of Snail mRNA. Moreover, the upregulation of METTL3 and YTHDF1 act as adverse prognosis factors for overall survival (OS) rate of liver cancer patients. Our study highlights the critical roles of m 6 A on regulation of EMT in cancer cells and translation of Snail during this process.

Targeted mRNA demethylation using an engineered dCas13b-ALKBH5 fusion protein

“…To test the utility of dCas13b-ALKBH5 for targeted m 6 A methylation, we selected potential candidate transcripts according to the following rules: 1) The RFKM of transcript is greater than 300 in m 6 A-seq according to our previous study; and 2) Only one m 6 A peak site was identified for one transcript. For those transcripts bearing m 6 A variated in cells undergoing EMT (in our previous study) 31 , they are preferentially selected due to the more dynamic variation of m 6 A. Finally, the transcript of CYB5A was chosen to investigate the effects of dCas13b mediated demethylation system (Figure 2 A and Figure S2A).…”

N6-Methyladenosine Regulates the Expression and Secretion of TGFβ1 to Affect the Epithelial–Mesenchymal Transition of Cancer Cells

“…RNA extraction with Trizol (Invitrogen) and real time PCR were performed according to the protocol used in our previous study [21].…”

“…Considering that METTL3 is critical to mRNA m 6 A methylation, we questioned whether the m 6 A of TGFβ1 mRNA regulated its expression. Firstly, we assumed from the m 6 A sequencing results from our previous study (Accession code GSE112795) [21] that TGFB1 mRNA contained two m 6 A modification peaks in 5 UTR and exon 1, respectively (Figure 2a). We performed m 6 A RNA-immunoprecipitation (RIP) qPCR and confirmed that m 6 A levels of TGFB1 mRNA reduced significantly in Mettl3 Mut/− cells (Figure 2b).…”

“…We further tested the potential effects of the METTL3/TGFβ1/Snail axis on the in vivo progression of cancer. We established high lung metastasis potential cancer cell models in our previous studies [21,34] and named them MDA-MB-231 LMF3 or BT-549 LMF3 cells. Both qRT-PCR and Western blot analysis showed that the expression of TGFβ1 and METTL3 increased in high lung metastasis potential cancer cells compared with that in the parental cells (Figure 7a,b).…”

“…For instance, METTL3 is necessary for the development and maintenance of mouse and human myeloid leukemia [20]. Our recent study indicated that METTL3 regulated the epithelial-mesenchymal transition (EMT) of cancer cells via Snail translation [21]. Although associations between m 6 A methylation and tumorigenesis, especially EMT process, have arisen for the last decade, the detailed mechanisms remained to be elucidated.EMT of cancer can be induced by a plethora of signaling pathways, and transforming growth factor β (TGFβ) is the prominent EMT inducer in cancer cells [22].…”