Figure 2. STF-118804 induces apoptosis without antecedent cell cycle arrest.

(A) Growth of MV411 cells in the absence or presence of STF-11804 (100 nM) or idarubicin (25 nM) was quantified by trypan blue exclusion. Errors bars represent standard error of the mean for three independent experiments.

(B) MV411 cells were treated with STF-118804 (100 nM) for the indicated times and assessed by flow cytometry for annexin V-FITC and propidium iodide staining. Double positive cells correspond to late stages of apoptosis. Data are representative of three independent experiments.

(C) Cell cycle status was assessed by propidium iodide staining of MV411 cells treated or untreated for the indicated times with STF-118804 (100 nM) or idarubicin (25 nM). STF-118804 induced accumulation of a sub-G₀ population at 48 hrs without antecedent reduction of the S/G2/M population, in contrast to idarubicin. Data are representative of three independent experiments.

(D) The presence of cleaved PARP (89 kD) was assessed by western blot analysis of lysates from MV411 or SEM leukemia cell lines treated with 100 nM STF-118804 for 24 (STF 24) or 36 (STF 36) hours, or 25 nM idarubicin for 24 hours (Ida 24). Data are representative of two independent experiments.

(E) Dose-response curve of MV411 cells treated with STF-118804 for 72 hours. Cell viability was measured by a resazurin-based assay (CellTiter-Blue) and a live cell protease-based assay (CellTiter-Fluor). Data represent three independent experiments performed in triplicate (± SEM). See also Figure S2.