AF10 Regulates Progressive H3K79 Methylation and HOX Gene Expression in Diverse AML Subtypes

Abstract

SUMMARY Homeotic (HOX) genes are dysregulated in multiple malignancies including several AML subtypes. We demonstrate that H3K79 dimethylation (H3K79me2) is converted to mono-methylation (H3K79me1) at HOX loci as hematopoietic cells mature thus coinciding with a decrease in HOX gene expression. We show that H3K79 methyltransferase activity as well as H3K79me1 to H3K79me2 conversion is regulated by the DOT1L co-factor AF10. AF10 inactivation reverses leukemia-associated epigenetic profiles, precludes abnormal HOXA gene expression and impairs the transforming ability of MLL-AF9, MLL-AF6 or NUP98-NSD1 fusions – mechanistically distinct HOX-activating oncogenes. Furthermore, NUP98-NSD1 transformed cells are sensitive to small-molecule inhibition of DOT1L. Our findings demonstrate that pharmacological inhibition of the DOT1L/AF10 complex may provide therapeutic benefit in an array of malignancies with abnormal HOXA gene expression.

MLL1 and DOT1L cooperate with meningioma-1 to induce acute myeloid leukemia

“…HOXA9 is overexpressed in about 50% of AML (36), and most recent data has suggested that normal as well as malignant later HOXA cluster expression may require DOT1L independent of the expression of a leukemogenic fusion protein that could mediate direct recruitment (23,37,38). We find that functional DOT1L is not universally required for high HOXA9 expression.…”

A Role for Monomethylation of Histone H3-K27 in Gene Activity inDrosophila

“…Besides the H3-K27 states tracked here, prior studies also associate H3-K9 monomethylation with active genes whereas K9me2 and K9me3 are highly correlated with repressed chromatin (BARSKI et al 2007;WANG et al 2008). Another intriguing example is H3-K79, where conversion of the active marks K79me2/3 to K79me1 accompanies Hox gene down-regulation in hematopoietic cells and leukemic transformation is associated with abnormally high K79me2/3 levels via dysfunction of the K79 methyltransferase DOT1 (DESHPANDE et al 2014). These examples suggest that methyl group addition/subtraction underlies key switches in gene activity and highlight the potential of chemotherapeutic strategies that interconvert target lysine methylations.…”

H3K36 Methyltransferases as Cancer Drug Targets: Rationale and Perspectives for Inhibitor Development

“…NUP98-NSD1 induces AML in vivo, sustains selfrenewal of myeloid stem cells in vitro and enforces expression of the HOXA7, HOXA9, HOXA10 and MEIS1 proto-oncogenes [8]. Expression of the HOXA and MEIS1 oncogenes appears to be responsible for the transforming activity of NUP98-NSD1, as inhibition of the DOT1L-AF10 complex in NUP98-NSD1 leukemia decreases HOXA gene expression and triggers d ifferentiation and apoptosis [49].…”

“…NUP98-NSD1 induces AML in vivo, sustains selfrenewal of myeloid stem cells in vitro and enforces expression of the HOXA7, HOXA9, HOXA10 and MEIS1 proto-oncogenes [8]. Expression of the HOXA and MEIS1 oncogenes appears to be responsible for the transforming activity of NUP98-NSD1, as inhibition of the DOT1L-AF10 complex in NUP98-NSD1 leukemia decreases HOXA gene expression and triggers d ifferentiation and apoptosis [49].NSD1 has also been reported to methylate nonhistone proteins, including the p65 subunit of NF-κB at Lys218 and Lys221. In response to cytokines such as IL-1β and TNF-α, NSD1-mediated methylation enhances NF-κB's transcriptional activation and DNA-binding activities [50], which are active in most cancer cells and regulate genes that control proliferation, resistance to apoptosis, angiogenesis, invasion and metastasis [51].…”