Fig. 3

Response of SAMHD1^KO cells to olaparib in monotherapy and combined with bendamustine/ ibrutinib. (A) Cell viability studies by MTT assay in response to increasing doses of olaparib (0.625–20 µM) for 72 h. Percentage of live cells is expressed relative to DMSO control. Differences between PGA-1 SAMHD1^WT and SAMHD1^KO clones are summarized by asterisks. Data are summarized as the mean ± SD of three independent experiments. (B) Drug response to olaparib (20 µM), bendamustine (20 µM) and combination of both drugs (ratio 1:1) in PGA-1 SAMHD1^WT and SAMHD1^KO by measuring cell viability with MTT assay after 72 h Data are summarized as the mean ± SD of three independent experiments. (C) Dose–response curve of viable cells (%, relativized to untreated cells) after treatment with olaparib, ibrutinib and their combination at a 1:1 ratio. Data are presented as the mean ± SD of three independent experiments. Combination index (CI) was calculated using Calcusyn. (D) Determination of cytotoxicity after 48-h treatment with olaparib (7.5 µM), ibrutinib (7.5 µM) and the combination of these drugs (1:1) in PGA-1 cells by measuring the percentage of apoptotic cells (annexin V + / PI +) with annexin V/PI staining. Data are presented as the mean ± SD of three independent experiments. (E) Western blot analyses reflecting PARP cleavage as an apoptosis marker after treatment with olaparib, ibrutinib and their combination (ratio 1:1).