1. ¹Institute of Biomedical Research, University of Birmingham Medical School, Birmingham B15 2TT, UK
2. ²School of Biosciences, University of Birmingham, Birmingham B15 2TH, UK
3. ³CRUK Institute of Cancer Research, University of Birmingham Medical School, Birmingham B15 2TT, UK

Correspondence: Professor BM Turner, Institute of Biomedical Research, Division of Immunity and Infection, University of Birmingham Medical School, Birmingham B15 2TT, UK. Fax: +44 121 414 3599; E-mail: b.m.turner@bham.ac.uk

⁴CAB and FLK contributed equally to this work

Received 21 April 2005; Accepted 28 June 2005; Published online 25 August 2005.

Abstract

Histone deacetylase inhibitors (HDIs) are a new class of drugs with significant antileukemic activity. To explore mechanisms of disease-specific HDI activity in acute myeloid leukaemia (AML), we have characterised expression of all 18 members of the histone deacetylase family in primary AML blasts and in four control cell types, namely CD34+ progenitors from umbilical cord, either quiescent or cycling (post-culture), cycling CD34+ progenitors from GCSF-stimulated adult donors and peripheral blood mononuclear cells. Only SIRT1 was consistently overexpressed (>2 fold) in AML samples compared with all controls, while HDAC6 was overexpressed relative to adult, but not neo-natal cells. HDAC5 and SIRT4 were consistently underexpressed. AML blasts and cell lines, exposed to HDIs in culture, showed both histone hyperacetylation and, unexpectedly, specific hypermethylation of H3 lysine 4. Such treatment also modulated the pattern of HDAC expression, with strong induction of HDAC11 in all myeloid cells tested and with all inhibitors (valproate, butyrate, TSA, SAHA), and lesser, more selective, induction of HDAC9 and SIRT4. The distinct pattern of HDAC expression in AML and its response to HDIs is of relevance to the development of HDI-based therapeutic strategies and may contribute to observed patterns of clinical response and development of drug resistance.