Cooperative cell death induction of the combination treatment with TRAIL and Olaparib.

<p>A–D): U87 (A), U373 (B), LN229 (C) and MDA-MB-468 (D) cells were treated with suboptimal dosages of TRAIL (A: 100 ng/ml, B: 25 ng/ml, C: TRAIL 200 ng/ml, D: 10 ng/ml), Olaparib (A–C: 10 µM, D: 5 µM) or the combination of both reagents for 48 hours. Thereafter, MTT assays were performed to determine cellular viability. E–F) GBM neurosphere culture (GS9-6) was treated with suboptimal dosages of TRAIL, Olaparib or the combination of both reagents and assessed for neurosphere formation 2 weeks after plating. G–H): U251 and GS9-6 (GBM neurosphere culture) cells were treated with suboptimal dosages of TRAIL, Olaparib or the combination of both reagents and stained with Annexin-V (FITC-conjugated) and Propidium iodide 24 hours after treatment. Cells were analyzed by flow cytometry to determine the fraction of apoptotic cells. Values are given as mean ± SEM of representative experiments. The unpaired t-test was used to calculate the p-values. A p-value of less than 0.05 (0.01 to 0.05) is indicated by one star “*”, whereas a p-value of less than 0.01 (0.001 to 0.01) is highlighted by two stars “**”. A p-value less than 0.001 is indicated by a star triplet (***). CO – Control, TR – TRAIL, OL – Olaparib, TR+OL – TRAIL + Olaparib.