N6-Methyladenosine RNA Modification in the Tumor Immune Microenvironment: Novel Implications for Immunotherapy

N6-methyladenosine (m(6)A) methylation is one of the most common modifications of RNA in eukaryotic cells, and is mainly regulated by m(6)A methyltransferases (writers), m(6)A demethylases (erasers), and m(6)A binding proteins (readers). Recently, accumulating evidence has shown that m(6)A methylation plays crucial roles in the regulation of the tumor immune microenvironment, greatly impacting the initiation, progression, and metastasis processes of various cancers. In this review we first briefly summarizes the m(6)A-related concepts and detection methods, and then describes in detail the associations of m(6)A methylation modification with various tumor immune components especially immune cells (e.g., regulatory T cells, dendritic cells, macrophages, and myeloid-derived suppressor cells) in a variety of cancers. We discuss the relationship between m(6)A methylation and cancer occurrence and development with the involvement of tumor immunity highlighted, suggesting novel markers and potential targets for molecular pathological diagnosis and immunotherapy of various cancers.