Fig. 7From: The SMAC mimetic BV6 sensitizes colorectal cancer cells to ionizing radiation by interfering with DNA repair processes and enhancing apoptosiscIAP1 and XIAP knockdown radiosensitizes colorectal cancer cells. Single cells from knockdown cell cultures were plated in a 3D extracellular matrix and irradiated with 0, 2, 4 or 6 Gy (single doses) 24 h thereafter. Colonies with more than 50 cells were counted microscopically 6–7 days after plating. a Typical 3D colony formation of non-irradiated (0 Gy) or irradiated (2 Gy) mock-treated (mock) or cIAP1/XIAP depleted (cIAP1+X si) cell cultures 6–7 days after plating (bar, 200 μm). b Plating efficiency of 3D grown mock, control siRNA (co), cIAP1 siRNA (cIAP1), XIAP siRNA (X) and cIAP1/XIAP (cIAP1+X) siRNA transfected cells was determined and normalized to control siRNA (co) treated cells. (means ± SD; n ≥3). c For measurement of 3D radiation survival, indicated knockdown cell cultures 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 control (co) siRNA treatment)Back to article page