Fig. 5

Irinotecan plus INK128 induces apoptotic cell death in human malignant peripheral nerve sheath tumor (MPNST) cell lines. a sNF96.2 cells were cultured with 500 nM of irinotecan, 20 nM of INK128, a combination of irinotecan and INK128, or dimethyl sulfoxide (DMSO), and their viability was measured. Values are mean ± SD fold changes relative to the measurement on day 0 in three independent biological experiments. b, c Experiment performed in panel a was repeated with ST8814 (b) or STS26T (c) cells. ST8814 cells were cultured with 350 nM of irinotecan, 120 nM of INK128 or a combination of irinotecan and INK128 or DMSO, while STS26T cells were cultured with 900 nM of irinotecan, 150 nM of INK128 or a combination of irinotecan and INK128 or DMSO. d Apoptotic sNF96.2, ST8814, or STS26T cells detected with Annexin V-FITC/propidium iodide (PI) staining, and analyzed by flow cytometry. Representative flow plots are shown (n = 3). Each cell line was cultured for 72 h (sNF96.2) or 48 h (ST8814 and STS26T) with the concentrations of irinotecan and INK128 shown in panel a, b or c. e–g Annexin-positive cells were counted in triplicate experiments with mean ± SD percentages of positive cells reported in the graphs. The Annexin V-positive and PI-negative cells were defined as early apoptotic cells, while the Annexin V- and PI double-positive cells were defined as late apoptotic cells. *p < 0.05, **p < 0.01 by Student’s t-test; n.s. = not significant