Cell killing induced by decay of 125I during the cell cycle: comparison of 125I-antipyrine with 125I-bovine serum albumin.
The lethal effects induced by the decay of 125I in synchronized L5178Y cells were studied by suicide experiments. We used 125I-antipyrine, which is freely diffusible in cells, and 125I-bovine serum albumin (BSA), which remains outside the cells. Synchronized cells mixed with either 125I-antipyrine or 125I-BSA were frozen and stored at -196 degrees C for various periods to accumulate 125I decays. A clonogenic assay was used to measure the killing of these stored cells. Cells in G1-S and G2-M phases were more sensitive than those in late S phase for both 125I treatments. The ratio of survival in late S to that in G1-S (late S/G1-S) obtained by the decay of 125I-antipyrine, however, was much smaller than that obtained by the decay of 125I-BSA in the dose range examined. These results suggest that Auger electrons emitted from 125I-antipyrine cause a high-LET-type effect. The reason for the high-LET effect must be the intracellular localization of 125I-antipyrine and its closer contact with DNA.
Miyazaki
N
N
Department of Radioisotope, Tokyo Institute of Psychiatry, Japan.
Shinohara
K
K
D000818:Animals; D000983:Antipyrine / Q000493:pharmacokinetics*; D002453:Cell Cycle / Q000502:physiology*; D016923:Cell Death; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects*; D007457:Iodine Radioisotopes; D007940:Leukemia L5178 / Q000473:pathology; D012710:Serum Albumin, Bovine / Q000493:pharmacokinetics*
D007457:Iodine Radioisotopes; D012710:Serum Albumin, Bovine; D000983:Antipyrine