LAUSR

OBJECTIVE As the main component of traditional Chinese medicine realgar, arsenic disulfide (As2S2) is widely used in treating myelodysplastic syndromes (MDS). The goal of the current study is to assess the effects of As2S2 on bone marrow mononuclear cells (BMMNC) of MDS. METHODS BMMNCs were obtained from 10 lower risk MDS patients, 5 higher risk MDS patients, and 3 healthy controls. Then, the cells were treated with As2S2 for 48h, using vorinostat (also known as SAHA) as control. Cell proliferation and apoptosis were detected. mRNA and protein levels of histone deacetylase-1 (HDAC1), Toll-like receptor 2 (TLR2), and erythroid transcription factor (GATA-1) were detected by quantitative real-time PCR and western blot analysis. RESULTS After As2S2 treatment in concentrations ranging from 3.125 to 100μmol/L, cell proliferation was inhibited in both lower risk and higher risk MDS. Fifty percent inhibitory concentrations were 24.4μmol/L and 23.6μmol/L, respectively, for lower and higher risk MDS. Apoptotic cells significantly increased in both types of MDS. mRNA and protein levels of HDAC1 and TLR2 were reduced, whereas GATA-1 was increased in both types of MDS. CONCLUSIONS As2S2 could inhibit cell proliferation and induce apoptosis through histone acetylation modulation in MDS. Similar to SAHA, As2S2 could reduce TLR2 activation and increase GATA-1 expression. Current data suggest epigenetic and immunological alternations are involved in therapeutic mechanisms of realgar in the treatment of MDS.