N6-Methyladenosine Demethylase Fto Promotes Growth and Metastasis of Gastric Cancer <i>via</i> M <sup>6</sup>A Modification of Caveolin-1 and Metabolic Regulation of Mitochondrial Dynamics

Abstract

Background: Gastric cancer (GC) is the fifth most common tumor and the third most deadly cancer worldwide. N6-methyladenosine (m6A) modification has been reported to play a regulatory role in human cancers. However, the exact role of m6A in GC remains largely unknown, and the dysregulation of m6A on mitochondrial metabolism has never been studied. Method: The expression level of FTO in the GC tissue was analyzed by real-time quantitative PCR, Western blotting, IF and IHC. Colorimetric m6A RNA methylation assay kit and Dot blotting were used to evaluate the level of m6A methylated RNA. In vitro assays, including cell viability, colony formation assay, wound healing assay and invasion assay were performed to detect the effects of FTO and caveolin-1 manipulation on the biological functions of GC cells. Xenografts models were constructed to evaluate the effects of FTO and caveolin-1 manipulation on the biological function of GC cell in vivo. HiSeq RNA-Seq was used to screen the potential targets of FTO. Real-time integrated cellular oxygen consumption rate (OCR) was measured using the Seahorse XF24 Extracellular Flux Analyzer. Finding: We demonstrated that FTO, a key demethylase for RNA m6A modification, was up-regulated in GC tissues, especially in tissues with liver metastasis. Functionally, FTO acted as a promoter for the proliferation and metastasis in GC. Moreover, FTO enhanced the degradation of caveolin-1 mRNA via its demethylation, which regulated the mitochondrial fission/fusion and metabolism. Interpretation: Our current findings provided some valuable insights into FTO-mediated m6A demethylation modification and could be used as a new strategy for more careful surveillance and aggressive therapeutic intervention. Funding: This project was supported by grants from the National Key R&D Plan (2018YFC1313400), National Natural Science Foundation of China (31701111), Young Talent Development Plan of Changzhou Health Commission (CZQM2020008, CZQM2020018) and Youth Talent Science and Technology Project of Changzhou Health Commission (QN202014). Declaration of Interest: None to declare. Ethical Approval: All animal experiments were approved by the Animal Care Committee of the Third Affiliated Hospital of Soochow University. All patients have provided written informed consent, and our study was preformed after formal approval by the Institutional Review Board of the Third Affiliated Hospital of Soochow University.