Figure 4
Irradiation reversed the resistance of H-157 cells to gefitinib. (A) Clonogenic survival curves for gefitinib and/or radiation treatments in H-157 cells. Cells attached to the flasks were treated with 100 nmol/L gefitinib, meanwhile, irradiated with graded doses of x-rays, rinsed after 48-hour incubation in drug-containing medium, and allowed to form colonies in drug-free medium. Surviving fractions for radiation + gefitinib were normalized by dividing by the surviving fraction for gefitinib only. Each test was performed 3 times. The radiation-enhancing (t = 7.65, P < 0.01) effect of gefitinib was comparable with that of gefitinib alone in H-157 cells. (B) Effects of gefitinib on H-157 cell growth after irradiation. There was no significant difference (t = 1.13, P > 0.05) in the growth rates between H-157 cells and gefitinib-treated cells as determined by cell counting, but the proliferative ability of the gefitinib and radiation treated cells was dramatically suppressed(t = 5.01, P < 0.05)in contrast with radiation-treated only.