A lncRNA from the FTO locus acts as an inhibitor of mRNA m6A methylation and p53 tumor suppression

The FTO gene locus has been linked to cancer and obesity through encoded N6-methyladenosine (m6A) demethylase FTO or inherited genomic variants (e.g. intronic single-nucleotide polymorphisms). Here we demonstrate that FTO-IT1, a long noncoding RNA (lncRNA) transcribed from a FTO gene intron, is upregulated during prostate cancer (PCa) progression and positively correlated with poor survival of patients with tumors only expressing wild-type p53. We show that RBM15, a mRNA/substrate binding subunit of the m6A methyltransferase complex binds and increases mRNA m6A methylation and stability of p53 transcriptional target genes; however, FTO-IT1 overexpression abolishes these effects by blocking RBM15 binding of p53 target gene mRNAs. Therapeutic targeting of FTO-IT1 restores mRNA m6A level and p53 signaling and inhibits PCa tumor growth in mice. Our study identifies FTO-IT1 lncRNA as a bono fide inhibitor of m6A methylation and p53 tumor suppression and nominates FTO-IT1 as a potential biomarker and therapeutic target of cancer. Overall design: [Dataset 1] 4 samples. Duplicates for CLIP-Seq samples with an antibody against RBM15 in 22Rv1 (CRL-2505) human prostate carcinoma cell line