Fig. 4From: The SMAC mimetic BV6 sensitizes colorectal cancer cells to ionizing radiation by interfering with DNA repair processes and enhancing apoptosisBV6 treatment decreases basal clonogenic survival and substantially radiosensitizes colorectal cancer cells. Single cells were plated in a 3D extracellular matrix and 24 h thereafter, cells were treated either with DMSO or increasing concentrations of BV6 (0.1, 0.25, 1, 1.5 μM) or were left untreated (mock). At 4 h after BV6 treatment, cells were irradiated with 0, 2, 4 or 6 Gy (single doses) and ≥6 days after plating colonies >50 cells were microscopically counted. a Typical colony formation of DMSO- or BV6-treated colorectal cancer cell lines ≥6 days after plating (bar, 200 μm). b Survival curves of indicated colorectal cancer cell lines after BV6 treatment were calculated and normalized to DMSO-treated cells (means ± SD; n ≥3; *P <0.05; **P <0.01; Student’s t-test). c To evaluate 3D radiation survival, single cells were pretreated for 4 h with DMSO or increasing concentrations of BV6 or left untreated (mock). Subsequently, cells were irradiated (0–6 Gy, single dose) and survival fractions relative to non-irradiated controls were calculated. Curves were fitted according to the linear quadratic model (means ± SD; n ≥3; *P <0.05; **P <0.01; Student’s t-test in comparison to DMSO-treated controls)Back to article page