Acute myeloid leukemia requires Hhex to enable PRC2-mediated epigenetic repression of Cdkn2a

  1. Matthew P. McCormack1,2
  1. 1Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia;
  2. 2Department of Medical Biology, University of Melbourne, Parkville, Victoria 3050, Australia;
  3. 3Bioinformatics Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia;
  4. 4Computing and Information Systems, University of Melbourne, Parkville, Victoria 3050, Australia;
  5. 5Lowy Cancer Research Centre and the Prince of Wales Clinical School, University of New South Wales, Sydney, New South Wales 2052, Australia;
  6. 6Yale University School of Medicine, New Haven, Connecticut 06510, USA;
  7. 7Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3050, Australia
  1. Corresponding author: mccormack{at}wehi.edu.au

Abstract

Unlike clustered HOX genes, the role of nonclustered homeobox gene family members in hematopoiesis and leukemogenesis has not been extensively studied. Here we found that the hematopoietically expressed homeobox gene Hhex is overexpressed in acute myeloid leukemia (AML) and is essential for the initiation and propagation of MLL-ENL-induced AML but dispensable for normal myelopoiesis, indicating a specific requirement for Hhex for leukemic growth. Loss of Hhex leads to expression of the Cdkn2a-encoded tumor suppressors p16INK4a and p19ARF, which are required for growth arrest and myeloid differentiation following Hhex deletion. Mechanistically, we show that Hhex binds to the Cdkn2a locus and directly interacts with the Polycomb-repressive complex 2 (PRC2) to enable H3K27me3-mediated epigenetic repression. Thus, Hhex is a potential therapeutic target that is specifically required for AML stem cells to repress tumor suppressor pathways and enable continued self-renewal.

Keywords

Footnotes

  • Received July 8, 2015.
  • Accepted November 23, 2015.

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