Fig 5.

(S)-2 triggers apoptosis in different cultured and primary AML cells. (A) Different AML cell lines were treated for 2 days without/with increasing (S)-2 concentrations and then submitted to the Annexinn V/PI assay to determine the amount of apoptotic cells within the population. IC₅₀ values represent the drug concentration (μM) needed for inducing 50% of cell population toward apoptosis relative to control; values were the means ± SD of three separate experiments. (B) Pro-apoptotic effects of (S)-2 in NB4 cells developed through the drug-mediated generation of ROS. Activation of apoptosis was revealed at 15 hrs, by the cleavage of PARP and phosphorylation of H2AX protein; and these events were efficiently contrasted by 15 mM N-Acetyl Cysteine (NAC) applied 2 hrs before drug addition; α-tubulin was used as the reference protein. (C) Ex vivo experiments on human different primary AML cells. May-Grünwald/Giemsa stained cytosmears of blasts (magnification: ×200) from peripheral blood of four newly diag nosed AML patients with M1, M2, M3 and M4 subtypes after 48 hrs of treatment without/with 1 and 2 μM drug. Peripheral blood mononuclear cells (PBMCs) from normal donors have also been isolated and treated as above after a 12-hr stimulation with PHA (125 μg/ml) and IL-2 (1 ng/ml).