The action of caffeine on X-irradiated HeLa cells. X. Depressed recovery from potentially lethal damage in cells containing 5-bromodeoxyuridine.
HeLa S3 cells were sensitized to the lethal action of 220-kV X rays by partially replacing the thymidine in their DNA with 5-bromodeoxyuridine (BrdU). To examine the expression of and recovery from potentially lethal radiation damage (PLD), both BrdU-grown and control cells were treated with 4 mM caffeine for increasing times up to 2 days, either immediately after irradiation or after increasing delays up to 28 h. When the same dose of X rays (3 Gy) was applied to BrdU-grown and control cells, the difference in survival that is found in the absence of caffeine disappeared after about 30 h of incubation in its presence; when isosurvival doses were applied (BrdU-grown cells, 2.5 Gy; control cells, 4 Gy), the control cells suffered more killing. When treatment with caffeine was delayed for progressively longer times after both groups of cells received 3 Gy, the control cells achieved a higher level of survival. These results indicate that the increased radiation sensitivity of cells containing BrdU derives from a decreased ability to repair PLD.
Labanowska
J
J
Department of Radiology, Washington University School of Medicine, St. Louis, Missouri 63108.
Beetham
K L
KL
Tolmach
L J
LJ
D001973:Bromodeoxyuridine / Q000494:pharmacology*; D002110:Caffeine / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects* / Q000528:radiation effects; D006367:HeLa Cells; D006801:Humans; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*
D011838:Radiation-Sensitizing Agents; D002110:Caffeine; D001973:Bromodeoxyuridine