The antagonistic effect of FTO on METTL14 promotes AKT3 m(6)A demethylation and the progression of esophageal cancer.

As the most abundant modification in eukaryotic messenger RNAs (mRNAs), N6-methyladenosine (m6A) plays vital roles in many biological processes. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and transcriptomic RNA sequencing (RNA-seq) were used to screen for m6A targets in esophageal cancer cells and patients. The role of m6A RNA methylase in esophageal cancer was also analyzed using bioinformatics. In vitro and in vivo experiments were used to analyze gene expression and function. CCK-8, colony formation, cell apoptosis and immunofluorescence staining assays were performed to evaluate the proliferation, migration and invasion of esophageal cancer cells, respectively. Western blot analysis, RNA stability, RIP and luciferase reporter assays were performed to elucidate the underlying mechanism involved. We found that the m6A demethylase FTO was significantly upregulated in esophageal cancer cell lines and patient tissues. In vivo and in vitro assays demonstrated that FTO was involved in the proliferation and apoptosis of esophageal cancer cells. Moreover, we found that the m6A methyltransferase METTL14 negatively regulates FTO function in esophageal cancer progression. FTO alone is not related to the prognosis of esophageal cancer, and its function is antagonized by METTL14. By using transcriptome-wide m6A-seq and RNA-seq assays, we revealed that AKT3 is a downstream target of FTO and acts in concert to regulate the tumorigenesis and metastasis of esophageal cancer. Taken together, these findings provide insight into m6A-mediated tumorigenesis in esophageal cancer and could lead to the design of new therapeutic strategies.

Wei R ，Zhao F ，Kong L ，Pu Y ，Li Y ，Zang C ... -  《-》

FTO mediated ERBB2 demethylation promotes tumor progression in esophageal squamous cell carcinoma cells.

N6-methyladenosine (m6A) is the most prevalent and internal modification that occurs in the messenger RNAs of eukaryotes. However, knowledge of the impact of these modifications on gene expression regulation remains limited. By using the in vitro MeRIP-seq and RNA-seq assays, we discovered that the mRNA demethylase FTO was significantly up-regulated in esophageal squamous cell carcinoma (ESCC) tissues and cells. Knockdown of FTO drastically suppressed the proliferation, migration, and invasion of ESCC cells. Furthermore, by using transcriptome-wide m6A-seq and RNA-seq assays, we identified ERBB2 is the target of FTO, which acts in concert in ESCC tumorigenesis and metastasis. Moreover, loss and gain functional studies suggested that the m6A reader YTHDF1 stabilizes ERBB2 mRNA via decoding the m6A modification. All these results uncovered a new signaling cascade, including FTO, YTHDF1, and ERBB2, which finely regulates the ESCC progression.

Zhao F ，Ge F ，Xie M ，Li Z ，Zang C ，Kong L ，Pu Y ，Zheng X ，Tan Y ... -  《-》

FTO facilitates cancer metastasis by modifying the m(6)A level of FAP to induce integrin/FAK signaling in non-small cell lung cancer.

Emerging evidence suggests the critical roles of N6-methyladenosine (m6A) RNA modification in tumorigenesis and tumor progression. However, the role of m6A in non-small cell lung cancer (NSCLC) is still unclear. This study aimed to explore the role of the m6A demethylase fat mass and obesity-associated protein (FTO) in the tumor metastasis of NSCLC. A human m6A epitranscriptomic microarray analysis was used to identify downstream targets of FTO. Quantitative real-time PCR (qRT‒PCR) and western blotting were employed to evaluate the expression levels of FTO and FAP in NSCLC cell lines and tissues. Gain-of-function and loss-of-function assays were conducted in vivo and in vitro to assess the effects of FTO and FAP on NSCLC metastasis. M6A-RNA immunoprecipitation (MeRIP), RNA immunoprecipitation (RIP), luciferase reporter assays, and RNA stability assays were used to explore the mechanism of FTO action. Co-immunoprecipitation (co-IP) assays were used to determine the mechanism of FAP in NSCLC metastasis. FTO was upregulated and predicted poor prognosis in patients with NSCLC. FTO promoted cell migration and invasion in NSCLC, and the FAK inhibitor defactinib (VS6063) suppressed NSCLC metastasis induced by overexpression of FTO. Mechanistically, FTO facilitated NSCLC metastasis by modifying the m6A level of FAP in a YTHDF2-dependent manner. Moreover, FTO-mediated metastasis formation depended on the interactions between FAP and integrin family members, which further activated the FAK signaling. Our current findings provided valuable insights into the role of FTO-mediated m6A demethylation modification in NSCLC metastasis. FTO was identified as a contributor to NSCLC metastasis through the activation of the FAP/integrin/FAK signaling, which may be a potential therapeutic target for NSCLC. Video Abstract.

Gao L ，Wang A ，Chen Y ，Cai X ，Li Y ，Zhao J ，Zhang Y ，Zhang W ，Zhu J ，Zeng Y ，Liu Z ，Huang JA ... -  《Cell Communication and Signaling》

FTO suppresses glycolysis and growth of papillary thyroid cancer via decreasing stability of APOE mRNA in an N6-methyladenosine-dependent manner.

N6-methyladenosine (m6A) modification is the most common chemical modification in mammalian mRNAs, and it plays important roles by regulating several cellular processes. Previous studies report that m6A is implicated in modulating tumorigenesis and progression. However, dysregulation of m6A modification and effect of m6A demethylase fat-mass and obesity-associated protein (FTO) on glucose metabolism has not been fully elucidated in papillary thyroid cancer (PTC). Quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry were performed to explore the expression profile of FTO in PTC tissues and adjacent non-cancerous thyroid tissues. Effects of FTO on PTC glycolysis and growth were investigated through in vitro and in vivo experiments. Mechanism of FTO-mediated m6A modification was explored through transcriptome-sequencing (RNA-seq), methylated RNA immunoprecipitation sequencing (MeRIP-seq), MeRIP-qPCR, luciferase reporter assays, RNA stability assay and RNA immunoprecipitation assay. FTO expression was significantly downregulated in PTC tissues. Functional analysis showed that FTO inhibited PTC glycolysis and growth. Further analyses were conducted to explore FTO-mediated m6A modification profile in PTC cells and Apolipoprotein E (APOE) was identified as the target gene for FTO-mediated m6A modification using RNA-seq and MeRIP-seq. FTO knockdown significantly increased APOE mRNA m6A modification and upregulated its expression. FTO-mediated m6A modification of APOE mRNA was recognized and stabilized by the m6A reader IGF2BP2. The findings showed that APOE also promoted tumor growth through glycolysis in PTC. Analysis showed that FTO/APOE axis inhibits PTC glycolysis by modulating IL-6/JAK2/STAT3 signaling pathway. FTO acts as a tumor suppressor to inhibit tumor glycolysis in PTC. The findings of the current study showed that FTO inhibited expression of APOE through IGF2BP2-mediated m6A modification and may inhibit glycolytic metabolism in PTC by modulating IL-6/JAK2/STAT3 signaling pathway, thus abrogating tumor growth.

Huang J ，Sun W ，Wang Z ，Lv C ，Zhang T ，Zhang D ，Dong W ，Shao L ，He L ，Ji X ，Zhang P ，Zhang H ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

RNA N6-methyladenosine demethylase FTO promotes breast tumor progression through inhibiting BNIP3.

Niu Y ，Lin Z ，Wan A ，Chen H ，Liang H ，Sun L ，Wang Y ，Li X ，Xiong XF ，Wei B ，Wu X ，Wan G ... -  《Molecular Cancer》