WTAP-mediated m 6 A modification of circSMOC1 accelerates the tumorigenesis of non-small cell lung cancer by regulating miR-612/CCL28 axis

Abstract

Abstract Background: Accumulating evidence reveals that deregulated N6-methyladenosine (m6A) RNA methylation and circular RNAs (circRNAs) are required for the tumorigenesis of non-small cell lung cancer (NSCLC). We aimed to uncover the role and underlying mechanism by which WTAP-mediated m6A modification of circRNA contributes to NSCLC. Methods: The differentially-expressed circRNAs were identified by a circRNA profiling microarray. The association of circSMOC1 with clinicopathological features and prognosis in patients with NSCLC was estimated by fluorescence in situ hybridization (FISH). WTAP-mediated m6A modification of circRNA was validated by methylated RNA immunoprecipitation (Me-RIP) and RIP assays. The role of circSMOC1 in NSCLC was estimated by in vitro functional experiments and in vivo tumorigenesis models. CircSMOC1-specific binding with miR-612 was verified by RIP, luciferase gene report and RT-qPCR assays. The effect of circSMOC1 and (or) miR-612 on CCL28 expression was detected by Western blotting analysis. Results: We found that the expression levels of circSMOC1 were elevated in NSCLC and associated with TNM stage and poor survival. Knockdown of circSMOC1 impaired the tumorigenesis of NSCLC in vitro and in vivo, whereas restored expression of circSMOC1 displayed the opposite effect. Furthermore, WTAP was upregulated in NSCLC and mediated m6A modification of circSMOC1; Knockdown of WTAP repressed cell growth and invasion and abolished circSMOC1-caused tumor-promoting effects. Then, circSMOC1 acted as a sponge of miR-612 to upregulate CCL28, and miR-612 inhibitor abrogated circSMOC1 knockdown-caused anti-proliferation effects and CCL28 downregulation in NSCLC cells. Conclusion: Our findings unveil that WTAP-mediated m6A modification of circSMOC1 accelerates the tumorigenesis of NSCLC by regulating miR-612/CCL28 axis.