Selective induction of apoptosis by histone deacetylase inhibitor SAHA in cutaneous T-cell lymphoma cells: relevance to mechanism of therapeutic action

J Invest Dermatol. 2005 Nov;125(5):1045-52. doi: 10.1111/j.0022-202X.2005.23925.x.


Suberoylanilide hydroxamic acid (SAHA), an orally administered inhibitor of histone deacetylases, is currently in phase II clinical trials for cutaneous T cell lymphomas (CTCL), but the mechanism of SAHA action is unknown. In this study, we investigated the anti-tumor effects of SAHA in CTCL cell lines and freshly isolated peripheral blood lymphocytes (PBL) from CTCL patients with high percentage of circulating malignant T cells. Three cell lines (MJ, Hut78, and HH) and PBL from 11 patients and three healthy donors were treated with SAHA (1, 2.5, and 5 microM) for 24 and/or 48 h. Apoptosis was determined by flow cytometry analysis of sub-G1 hypodiploid nuclei and/or annexin V binding populations. Acetylated histones and apoptosis-associated proteins were detected by Western blotting. SAHA at 1-5 microM for 24 and 48 h induced apoptosis in a concentration- and time-dependent manner in three cell lines: MJ (0%-7% and 1%-32%), Hut78 (4%-36% and 5%-54%), and HH (4%-67% and 8%-81%). SAHA at 1-5 muM for 48 h also induced more apoptosis of patients' PBL than healthy donors' (15%-32%versus 6%-13%, p < 0.05). SAHA treatment caused an accumulation of acetylated histones (H2B, H3, and H4), an increase of p21(WAF1) and bax proteins, a decrease of Stat6 and phospho-Stat6 proteins, and activation of caspase-3 in CTCL cells. Our data suggest that selective induction of malignant T cell apoptosis and modulation of acetylated histones, p21(WAF1), bax, Stat6, and caspase-3 may underlie the therapeutic action of SAHA in CTCL patients.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation / drug effects
  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use*
  • Apoptosis*
  • Caspase 3
  • Caspases / metabolism
  • Cell Line, Tumor
  • Cyclin-Dependent Kinase Inhibitor p21 / analysis
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • Enzyme Inhibitors / therapeutic use*
  • Histone Deacetylase Inhibitors*
  • Histones / analysis
  • Histones / metabolism
  • Humans
  • Hydroxamic Acids / pharmacology
  • Hydroxamic Acids / therapeutic use*
  • Lymphoma, T-Cell, Cutaneous / chemistry
  • Lymphoma, T-Cell, Cutaneous / drug therapy*
  • Lymphoma, T-Cell, Cutaneous / enzymology
  • STAT6 Transcription Factor / analysis
  • STAT6 Transcription Factor / metabolism
  • Vorinostat


  • Antineoplastic Agents
  • CDKN1A protein, human
  • Cyclin-Dependent Kinase Inhibitor p21
  • Enzyme Inhibitors
  • Histone Deacetylase Inhibitors
  • Histones
  • Hydroxamic Acids
  • STAT6 Transcription Factor
  • STAT6 protein, human
  • Vorinostat
  • CASP3 protein, human
  • Caspase 3
  • Caspases