title: Enhancement of radiation killing of cultured mammalian cells by cordycepin.
abstract: Asynchronous populations of rat hepatoma cells (H4) in log-phase growth survived a 3-hour exposure to cordycepin (3'-deoxyadenosine), and RNA antimetabolite, in a simple exponential fashion with a 'DO' of 43.8 microM/l. When cordycepin-treated cells were exposed to X-irradiation, the resultant survival levels were much lower than one would expect were the agents simply additive. Patterns of X-ray survival of cells treated with cordycepin were dependent on drug concentration, the predominant effect being to decrease the DO of the X-ray survival curve. The increased sensitivity of cells exposed to cordycepin to subsequent X-ray treatment persists for longer than 4 hours after drug administration. Although immediate cordycepin post-treatment of X-irradiated cells is less effective than pre-treatment, the interaction is still significant. Cordycepin treatment did not appear to reduce split-dose recovery or to inhibit the rejoining of single-strand breaks as measured by DNA sedimentation in alkaline-sucrose gradients.
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured / Q000528:radiation effects*; D004260:DNA Repair / Q000187:drug effects; D004273:DNA, Neoplasm / Q000378:metabolism / Q000528:radiation effects; D003609:Dactinomycin / Q000633:toxicity; D003839:Deoxyadenosines / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D008113:Liver Neoplasms; D011838:Radiation-Sensitizing Agents; D051381:Rats; D013997:Time Factors; D014965:X-Rays
chemical_list: D004273:DNA, Neoplasm; D003839:Deoxyadenosines; D011838:Radiation-Sensitizing Agents; D003609:Dactinomycin