Differential effect of 9β-chloro-16,16-dimethyl prostaglandin E2 (Nocloprost) on the radiation response of human normal fibroblasts and colon adenocarcinoma cells

The possible influence of 9β-chloro-16, 16-dimethyl prostaglandin E2 (nocloprost) on the effect of137 Cs γ irradiation was investigated comparatively in human normal fibroblasts and colon adenocarcinoma cells. By itself, the compound did not influence the proliferation of cells of either cell type or the clonogenic capacity of carcinoma cells. Moreover, nocloprost did not induce any DNA strand breakage, as evaluated by neutral elution, in cells of either cell type. A 2-h incubation with nocloprost before irradiation induced an enhancement of fibroblast survival after an exposure of 10 Gy. This protective effect was not observed in adenocarcinoma cells under the same treatment conditions. The amount of double-strand breaks induced by 50 Gy was reduced in normal cells but not in tumor cells exposed to the prostaglandin analog before irradiation. Moreover, incubation with nocloprost for 2 h after irradiation remarkably enhanced the rate of rejoining of DNA breaks in fibroblasts but not in adenocarcinoma cell...