Cotreatment with DZNep and PS exerts a greater antileukemia effect than either agent alone in primary AML cells. (A) Peripheral blood or bone marrow from 4 patients with AML, CD34⁺ cells enriched from 4 AML patients, and CD34⁺ cells from 2 normal donors were treated with the indicated concentrations of DZNep and/or PS for 48 hours. Then, the percentages of nonviable cells for each drug alone or drug combination were determined by trypan blue dye uptake in a hemocytometer. Columns represent the mean of the samples; bars represent SEM. *Values significantly greater (P < .05) than those after treatment with either agent alone at the indicated concentrations in the AML samples. †Values significantly less (P < .05) in normal CD34⁺ versus leukemia samples for the drug combinations. (B) Primary AML cells were treated with the indicated concentrations of DZNep and/or PS for 24 hours. After treatment, cell lysates were prepared and immunoblot analysis was performed for EZH2, SUZ12, EED, and DNMT1. The expression levels of β-actin in the lysates served as the loading control. (C) CD34⁺/CD38⁻/Lin⁻ cells enriched from the bone marrow of AML patients were treated with the indicated concentrations of DZNep and/or PS for 48 hours. The percentages of nonviable cells for each drug alone or drug combination were then determined by trypan blue dye uptake in a hemocytometer. Columns represent the mean of the samples; bars represent SEM. (D) Immunoblot analyses of CD34⁺ cells from a normal donor treated with the indicated concentrations of DZNep and/or PS for 24 hours. The expression levels of β-actin in the lysates served as the loading control.