N6-methyladenosine modification is essential for prostate cancer cells

N6-methyladenosine (m6A) modification of messenger RNAs (mRNAs) is a pivotal mechanism controlling mRNA fate in cells. RNA m6A modification is regulated by the functional balance between methyltransferases and demethylases. Here we demonstrated that FTO-IT1 enhancer RNA (eRNA), a long non-coding RNA (lncRNA) transcribed from the last intron of FTO gene is significantly upregulated in CRPC and aggressive tumors compared to primary tumors. FTO-IT1 knockout by CRISPR/Cas9 almost completely blocks growth and G1-S cell cycle transition of both androgen-sensitive and castration-resistant prostate cancer cells. Meanwhile, the mRNA m6A was dramatically increased in FTO-IT knockout PCa cells and we identified FTO-IT1 as a binding partner of FTO. From m6A-seq, we unexpectedly found hypermethylated m6A associated with upregulated levels of the mRNAs for p53 signaling pathway genes in 22Rv1 prostate cancer cells. Mechanistic study showed that FTO-IT1 recruits FTO to the P53 target mRNA to promote their m6A demethylation, which leads to their degradation. Overall design: MeRIP-seq was performed on both wild-type and FTO KO prostate cancer cells