摘要
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 μ M) 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 μ M 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 μ M for 48 h also induced more apoptosis of patients’ PBL than healthy donors’ (15% - 32% versus6% - 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, p21WAF1, bax, Stat6, and caspase-3 may underlie the therapeutic action of SAHA in CTCL patients.
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 μM） 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 μM 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 μM for 48 h also induced more apoptosis of patients＇ PBL than healthy donors＇ （15% - 32% versus6% - 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,
