Effects of resveratrol (RSV) and ionizing radiation (IR) on survival of prostate cancer (PrCa) cells. A. Cells were incubated with increasing doses of RSV (0-10 μM) and allowed to form colonies. Colonies (> 50 cells) were counted. Results are expressed as the surviving fraction compared to untreated control (see Methods). '*' p < 0.05 compared to untreated PC3 cells, '#' p < 0.05 compared to untreated 22RV1 cells, '+' p < 0.05 compared to untreated PNT1A cells. B. Cells were pre-treated with RSV (0-10 μM) followed by treatment with a single fraction of IR (2 Gy) and allowed to grow and form colonies. Treatment values were normalized to untreated controls and surviving fractions are presented as percent of control. Shown is the mean of 4-5 independent experiments ± standard error (SE). '*' p < 0.05 compared to 2 Gy treated PC3 cells, '#' p < 0.05 compared to 2 Gy treated 22RV1 cells, '+' p < 0.05 compared to 2 Gy treated PNT1A cells. C. Projected proportion of tumour survival after treatment with 0 - 80 Gy was estimated using the Surviving Fraction at 2 Gy (SF2) values for control and RSV (5 μM) treated PNT1A, PC3 and 22RV1 cells. SF2n was determined as the tumour proportion surviving after "n" 2 Gy fractions, assuming iso-effectiveness of each fraction. Values were plotted up to a scale of 1 × 10-11 to reflect elimination of tumour of 50 - 100 gr expected to contain 5 - 10 × 1010 cells.