While the current epigenetic drug development is still largely restricted to target DNA methylome, emerging evidence indicates that histone methylome is indeed another major epigenetic determinant for gene expression and frequently deregulated in acute myeloid leukaemia (AML). The recent advances in dissecting the molecular regulation and targeting histone methylome in AML together with the success in developing lead compounds specific to key histone methylation-modifying enzymes have revealed new opportunities for effective leukaemia treatment. In this article, we will review the emerging functions of histone methyltransferases and histone demethylases in AML, especially MLL-rearranged leukaemia. We will also examine recent preclinical and clinical studies that show significant promises of targeting these histone methylation-modifying enzymes for AML treatment.

While β-catenin has been demonstrated as an essential molecule and therapeutic target for various cancer stem cells (CSCs) including those driven by MLL fusions, here we show that transcriptional memory from cells of origin predicts AML patient survival and allows β-catenin-independent transformation in MLL-CSCs derived from hematopoietic stem cell (HSC)-enriched LSK population but not myeloid-granulocyte progenitors. Mechanistically, β-catenin regulates expression of downstream targets of a key transcriptional memory gene, that is highly enriched in LSK-derived MLL-CSCs and helps sustain leukemic self-renewal. Suppression of sensitizes LSK-derived MLL-CSCs to β-catenin inhibition resulting in abolishment of CSC transcriptional program and transformation ability. In addition, further molecular and functional analyses identified Prmt1 as a key common downstream mediator for β-catenin/ functions in LSK-derived MLL-CSCs. Together, these findings not only uncover an unexpectedly important role of cells of origin transcriptional memory in regulating CSC self-renewal, but also reveal a novel molecular network mediated by β-catenin/Hoxa9/Prmt1 in governing leukemic self-renewal.