Fig. 3
Flow cytometry analysis of cell cycle distribution. (A) Gating strategy: Exemplary flow cytometry results of UM-SCC-47 treated with vehicle control (DMSO) or combined treatment (30 µM SCR130 + 2 Gy). At first, doublets and cell debris (I) were excluded. Afterwards, the amount of cells in the different cell cycle phases was determined according to their DNA content (II). (B) Cell cycle analysis: Cells in G0/G1 phase (filled) and G2/M phase (dashed) divided in unirradiated (0 Gy, blue) and irradiated (2 Gy, green) samples in different HPV-negative and HPV-positive HNSCC cell lines and healthy fibroblasts after treatment. Cells were treated with 15 or 30 µM SCR130; half of the samples additionally received 2 Gy IR 3 h afterwards. Vehicle control was treated with the same volume DMSO as used for 30 µM SCR130 (0 Gy). Statistically significant differences were calculated between 2 Gy and 30 µM SCR130 + 2 Gy (for G0/G1 and G2/M) by two-tailed Mann-Whitney test to evaluate the radiosensitizing effect of SCR130. Each value represents mean ± SD (n ≥ 4). *p = 0.028, **p = 0.004, except UD-SCC-2 G0/G1 **p = 0.008.
