RNA N6-methyladenosine modification in cancers: current status and perspectives

N 6 -methyladenosine (m 6 A), the most abundant internal modification in eukaryotic messenger RNAs (mRNAs), has been shown to play critical roles in various normal bioprocesses such as tissue development, stem cell self-renewal and differentiation, heat shock or DNA damage response, and maternal-to-zygotic transition. The m 6 A modification is deposited by the m 6 A methyltransferase complex (MTC; i.e., writer) composed of METTL3, METTL14 and WTAP, and probably also VIRMA and RBM15, and can be removed by m 6 A demethylases (i.e., erasers) such as FTO and ALKBH5. The fates of m 6 A-modified mRNAs rely on the functions of distinct proteins that recognize them (i.e., readers), which may affect the stability, splicing, and/or translation of target mRNAs. Given the functional importance of the m 6 A modification machinery in normal bioprocesses, it is not surprising that evidence is emerging that dysregulation of m 6 A modification and the associated proteins also contributes to the initiation, progression, and drug response of cancers. In this review, we focus on recent advances in the study of biological functions and the underlying molecular mechanisms of dysregulated m 6 A modification and the associated machinery in the pathogenesis and drug response of various types of cancers. In addition, we also discuss possible therapeutic interventions against the dysregulated m 6 A machinery to treat cancers.