Effects of daunomycin and radiation on cell-survival and repair of DNA single-strand breaks.
The combined action of Daunomycin and irradiation was investigated using mouse L-929 cells in culture. Survival of cells was measured with the colony assay. Sedimentation in alkaline sucrose gradients was used to study repair of DNA single-strand breaks (SSB) in the presence of various concentrations of Daunomycin. A small increase in radio-sensitivity, as measured by decreasing Do, was obtained for doses of Daunomycin that are considerably toxic to the cells (0.1 microgram/ml). However, the Dq values remained constant even at high concentrations indicating that Daunomycin does not interfere with recovery processes. The rate of rejoining of SSB remained constant up to 1.0 microgram/ml, whereas concentrations of Daunomycin as high as 10 microgram/ml reduced the velocity of repair by a factor of 13. Our data show that concentrations of Daunomycin similar to those required for other DNA-binding drugs are required to inhibit SSB repair. For clinical purposes, no increase in tumour-killing efficiency may be expected from a combined treatment with Daunomycin and radiation.
D000818:Animals; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003470:Culture Media; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D004277:DNA, Single-Stranded; D003630:Daunorubicin / Q000494:pharmacology*; D003864:Depression, Chemical; D066298:In Vitro Techniques; D007739:L Cells / Q000187:drug effects / Q000473:pathology* / Q000528:radiation effects; D051379:Mice; D008938:Mitosis / Q000187:drug effects; D011832:Radiation Injuries / Q000473:pathology
D003470:Culture Media; D004277:DNA, Single-Stranded; D003630:Daunorubicin