N6-methyladenosine Methyltransferase METTL3 Promotes Colorectal Cancer Cell Proliferation Through Enhancing MYC Expression

Background: N6-methyladenosine(m6A)modification is the most common chemical modification in eukaryotic mRNA,which plays a crucial role in reg?lating mRNA stability,splicing,and translation.METTL3(methyltransferase like 3),a major RNA N6-adenosine methyltransferase,has been reported to participate in the progression of many cancers.However,the role and mechanism of METTL3 in colorectal cancer(CRC)remain unclear.Methods: Quantitative real-time PCR(qRT-PCR),western blotting and immunohistochemical(IHC)were performed to explore differential expression of METTL3 in CRC tissues.The GraphPad Prism 5 was used to analyze the relationship between METTL3 expression and the clinicopathological characteristics of patients.Lentivirus expression vectors were used to construct shRNA interference plasmid and PCDH overexpression plasmid and to establish stable cell line.CCK-8 assay,colony formation assay,Flow cytometry,transwell assay and tumorxenografts experiment were used to investigate the effect of METTL3 on CRC cell function in vitro and in vivo.The qRT-PCR and western blotting were used to screen downstream targets of METTL3.The m6 A ELISA assays and RNA immunoprecipitation(RIP)were performed to explore the underlying mechanisms of METTL3 regulating the expression of downstream targets.Results: In this study,we found that METTL3 was significantly upreg?lated in CRC and upreg?lation of METTL3 was associated with clinicopathological features.Functionally,knockdown of METTL3 suppressed CRC cell proliferation both in vitro and in vivo.In contrast,overexpression of METTL3 promoted the proliferation of CRC cell.Mechanistically,METTL3 exerted its oncogenic function thro?gh enhancing MYC expression,at least partially via an m6A-IGF2BP1-dependent manner.Conclusions: our study demonstrated that METTL3 was frequently upreg?lated in human CRC and promoted CRC cell proliferation tho?gh enhancing MYC expression,at least partially via an m6A-IGF2BP1-dependent manner.This provided new insights into the molec?lar mechanisms underlying the development of colorectal cancer.