DNA damage in Panc-1 cells.

<p>(A) Pan-nuclear γH2AX signals of Panc-1 cells normalized to values of mock treated cells at time points 1 h and 12 h after treatments as surrogates for DNA double strand breaks (n = 3). SFN-treated cells were incubated with either 20 μM or 40 μM SFN for 24 h and afterwards if indicated irradiated with 4 Gy at time point 0 h. (B+C) Western blot of NHEJ pathway proteins after treatment of Panc-1 cells with SFN for 24 h and statistics of their band densities normalized to the loading control. For statistics data of Students t-test are shown (* p<0.05, ** p<0.01, *** p<0.001).</p

Sensitizer enhancement ratios (SER).

<p>SERs for an estimated 50%, 10% and 1% surviving fraction for every cell line and each for low and high concentrations of SFN.</p

Cell cycle distribution in Panc-1 cell.

<p>Cell cycle distribution at different time points: -2 h is the start of 40 μM SFN exposure, 0 h the time point of RT with 4 Gy and the other time points mark 12 h and 24 h after treatment. (A) Example of stacked ModFit curves of Panc-1 cell cycle raw data at the different time points and for the different treatments with G1 and G2 peaks. (B) Relative cell cycle distribution of G1, S and G2/M phase for Panc-1 cells including results of Students t-test of G2/M proportions between control and treatments (* p<0.05, ** p<0.01). (C) Ratios of G2/M and G1 proportion including results of Students t-test in comparison to the respective control (* p<0.05, ** p<0.01).</p

Statistics of G2/M population over time.

<p>Means of relative G2/M population in % (± SEM) with statistics (n = 3; t-test).</p

Clonogenic survival results.

<p>Results of clonogenic survival experiments (n = 3) for each pancreatic cancer cell line after exposure to SFN in a low (2 μM, for MIA PaCa-2 only 1 μM) or high dose (10 μM, for MIA PaCa-2 only 5 μM) for 24 h followed by RT in a low (2 Gy) or high dose (6 Gy), and combination of both. (A) Survival grouped by treatments including Students t-test statistics (* p<0.05, ** p<0.01, *** p<0.001, **** p<0.0001). (B) Logarithmic survival as function of dose for radiation and co-treatments as well as calculated artificial theoretical control curves of assumed isoeffective radiation doses for low (dotted) and high dose SFN (dashed), respectively. Co-treatments with a surviving fraction below the respective theoretical control curve can be considered as supra-additive (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0180940#sec006" target="_blank">materials and methods</a> section).</p