Advances in nucleoside analogues as methyltransferase inhibitors

As the second largest cofactor after ATP in body, S-adenosyl-L-methionine (SAM) is responsible for methyl donor in SAM-dependent methyltransferases (MTases). The methylation of essential ingredients (e.g., DNA, RNA, protein) plays a critical role in epigenetic regulation, cellular signal transduction and metabolic cycles, which is closely related to different kinds of diseases. Therefore, SAM-dependent methyltransferases are considered as promising drug targets. Currently, a growing number of nucleoside analogues have been developed as SAM-competitive inhibitors, blocking the downstream signaling pathways to cure diseases. In the review, we outline the design strategy and optimization process of methyltransferase inhibitors, analyze the shortcomings and solutions of developing nucleoside derivatives as MTase inhibitors, to provide guidance and broad direction to the development of nucleoside MTase inhibitors.