Figure 5

Survival of PC-3 cells after 24 h pretreatment with genistein 10 μM (left) and with estradiol 10 μM (right), followed by irradiation with single doses between 0.5 and 4 Gy, followed by immediate-plating. Survival was expressed relative to sham-irradiated controls. Error bars represent standard errors. A polynominal equation was used to fit the low-dose hyper-radiosensitivity region of the control curves while the genistein and estradiol curves followed a linear-quadratic equation. Incubation with genistein and estradiol abolished the HRS to low irradiation doses seen in the controls (genistein 10 μM vs. controls: 0.4 Gy: p < 0.01; 0.6 Gy: p = 0.027; estradiol 10 μM vs. controls: 0.4 Gy: p < 0.001; 0.6 Gy: p < 0.001). At and above 2 Gy there were no significant differences between the surviving clones after hormonal incubation and controls.