FIG. 5.

Survival of HMEC (panel a) and SA-NH cells (panel b) transfected with SOD2 siRNA and exposed to 2 Gy of 250 kVp X rays 24 h after treatment with 40 μM WR1065, sham-transfected cells treated with 40 μM WR1065 and irradiated 24 h later, and cells irradiated in the absence of thiol treatment. Each bar represents the mean ± SEM of three separate experiments. Panel a: Compared to the radiation-only group, HMEC protection factors (PF) of 0.94, P = 0.94, and 1.34, P < 0.001, were calculated for the SOD2 siRNA + 40 μM WR1065 and the 40 μM WR1065 treatment conditions, respectively. HMEC not exposed to WR1065, exposed to 40 μM and assayed 24 h later, and transfected with SOD2 siRNA, exposed to 40 μM WR1065 and assayed 24 h later exhibited SOD2 activities of 0.048, 0.282 and 0.046 U/10⁶ cells, respectively. Panel b: Compared to the radiation-only group, SA-NH cell protection factors of 0.75, P < 0.001, and 1.35, P < 0.001, were calculated for the SOD2 siRNA + 40 μM WR1065 and the 40 μM WR1065 treatment conditions, respectively. SA-NH cells not exposed to WR1065, exposed to 40 μM WR1065 and assayed 24 h later, and transfected with SOD2 siRNA, exposed to 40 μM WR1065 and assayed 24 h later exhibited SOD2 activities of 0.018, 0.117 and 0.012 U/10⁶ cells, respectively. P values were calculated using a two-tailed t test.