DNA Methylation in Cancer and Development: An Evolving Paradigm

DNA methylation is an epigenetic mark which, in mammals, occurs primarily on position 5 of cytosines, especially at those found in the context of CpG dinucleotides. This CpG methylation is known to play a major role in gene regulation. Cytosine methylation is regulated by the DNA methyltransferases, responsible for adding the methyl group to unmethylated CpGs, and the TET dioxygenases, involved in the DNA demethylation pathway. Initially, DNA methylation was believed to be important mainly for gene silencing through promoter DNA methylation, especially at CpG-rich promoters containing CpG islands. However, our understanding of the role that DNA methylation plays in gene regulation during normal development and how this process becomes deregulated in cancer, has evolved in recent years. Moreover, the discovery of frequent mutations in DNMT3A and TET2 both in clonal hematopoiesis of indeterminate significance as well as in many hematological malignancies has brought new interest into understanding what role DNA methylation plays in normal HSC function as well as how it contributes to malignant transformation. In this session, we will review the current understanding in the field of DNA methylation and gene regulation, and present data on DNA methylation in normal HSCs as well as the role that this epigenetic mark plays during leukemic transformation in acute myeloid leukemia.