title: Selective induction of apoptosis by histone deacetylase inhibitor SAHA in cutaneous T-cell lymphoma cells: relevance to mechanism of therapeutic action.
abstract: 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.
authors.affiliation: Department of Dermatology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA. czhang@mdanderson.org
authors.forename: Chunlei
authors.initials: C
authors.lastname: Zhang
authors.forename: Victoria
authors.initials: V
authors.lastname: Richon
authors.forename: Xiao
authors.initials: X
authors.lastname: Ni
authors.forename: Rakhshandra
authors.initials: R
authors.lastname: Talpur
authors.forename: Madeleine
authors.initials: M
authors.lastname: Duvic
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000032:analysis / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000032:analysis / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology / Q000627:therapeutic use*; D016410:Lymphoma, T-Cell, Cutaneous / Q000737:chemistry / Q000188:drug therapy* / Q000201:enzymology; D050800:STAT6 Transcription Factor / Q000032:analysis / Q000378:metabolism; D000077337:Vorinostat
chemical_list: D000970:Antineoplastic Agents; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D000077337:Vorinostat; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases