The m6A methyltransferase METTL3 aggravates the progression of nasopharyngeal carcinoma through inducing EMT by m6A-modified Snail mRNA.

ABSTRACT

BACKGROUND: This study aims to elucidate the role of METTL3 in aggravating the progression of NPC through m6A modification on Snail and thus the stimulated epithelial-mesenchymal transition (EMT). METHODS: Differential expressions of METTL3 in 48 paired NPC tissues and paracancerous tissues were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Its level in NPC patients with different clinical stages and metastatic states was examined. Prognostic potential of METTL3 in NPC patients was assessed by Kaplan-Meier method. After knockdown of METTL3, expression changes of Snail and EMT-related genes, as well as invasive and migratory abilities in SUNE-1 cells were detected. The interaction between Snail with METTL3 and IGF2BP2 was verified by RIP (RNA-Binding Protein Immunoprecipitation) assay. At last, the roles of METTL3/Snail regulatory loop in influencing EMT and metastasis of NPC were clarified. RESULTS: METTL3 was upregulated in NPC tissues than that of paracancerous ones. NPC patients with advanced stage or lymphatic metastasis expressed higher level of METTL3. Kaplan-Meier curves revealed that NPC patients expressing high level of METTL3 suffered worse prognosis. Knockdown of METTL3 downregulated protein levels of Snail and N-cadherin, while E-cadherin was upregulated in SUNE-1 cells. Meanwhile, knockdown of METTL3 inhibited invasive and migratory abilities in NPC cells. RIP assay confirmed the interaction between Snail and METTL3. Besides, knockdown of METTL3 decreased the enrichment abundance of Snail in anti-IGF2BP2. Overexpression of Snail partially reversed the regulatory effects of METTL3 on EMT-related gene expressions and metastatic abilities in NPC. CONCLUSIONS: METTL3 is upregulated in NPC, which regulates EMT and metastasis in NPC cells through m6A-modified Snail mRNA.