Fig. 3
DKK3 status does not significantly modulate intrinsic radiosensitivity but may contribute to radiation-induced senescence. N/TERT 1 keratinocytes were irradiated 24 h after siRNA-mediated DKK3 knockdown (DKK3 siRNA), nontargeting (NT) siRNA, doxycycline-free medium (control) or doxycycline-mediated overexpression of DKK3 (DKK3 ↑ ). a Relative DKK3 mRNA expression levels at 24 h after DKK3 modulation. b Flow cytometric evaluation of apoptosis-associated caspase-3 activation at 24 h and 72 h after irradiation with 4 Gy (n = 3). c Clonogenic survival at different radiation doses (n = 3). d Flow cytometric evaluation of cell cycle arrest in the G2 phase at 24 h and 72 h after irradiation with 4 Gy (n = 3) (see also supplementary Fig. 10b). e Microscopic evaluation of senescence-associated β-galactosidase (SA-β-gal) activity (n = 15 images from 3 replicates). Representative images of stained samples and automated quantification of SA-β-gal-positive cells (%). Scale bars: 50 μm. The data are presented as the means ± SEMs. Statistical analysis was performed via Student’s t test with Holm‒Šidák’s multiple comparison test (a, b, d, e) or one-way ANOVA with Tukey’s multiple comparisons test (c), *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 compared with 0 Gy in the same treatment group or as indicated
