Fig. 6

qRT-PCR for mRNA expression analysis. (A) Relative quantification of LIG4 mRNA compared to DMSO control in different HPV-negative and HPV-positive HNSCC cell lines after treatment. Cells were treated with 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). (B) LIG4 baseline expression in the different cell lines: relative quantification of DMSO controls compared to Cal33. (C) Regulation of different cell cycle control and DNA repair genes in the different cell lines after treatment (according to A, from left to right: 2 Gy, 30 µM SCR130, 30 µM SCR130 + 2 Gy) relative to DMSO control (white). Upregulation is represented by increasing intensity of blue color, downregulation by green color. Boxes with “x” (ABCB1, ABCG2) represent undetectable low expression. Statistically significant differences were calculated between 2 Gy and 30 µM SCR130 + 2 Gy (log transformed data of relative gene expression) by one-tailed Mann-Whitney test to evaluate the radiosensitizing effect of SCR130. Each value represents mean ± SD (n = 4), applies for A, B, and C. *p = 0.014.