Erschienen in:
Radiation Research, 108 (1986) 1, Seite 43-51
Sprache:
Englisch
ISSN:
0033-7587;
1938-5404
Entstehung:
Anmerkungen:
Beschreibung:
Iodine-125, in the form of$5\text{-}[{}^{125}{\rm I}]\text{iododeoxyuridine}\ ({\rm I}\text{-}{\rm UdR})$, was incorporated into the DNA of SV40 transformed Chinese hamster embryo cells. Disintegration of the125I led to increased cell killing with increasing dose as measured by the colony-forming ability of single cells. The$D_{37}$(the dose at which 37% of the cells survive) amounts to 95 decays per cell, corresponding to 0.66 Gy. Variations in the copy number of specific DNA sequences was measured by using dispersed cell blotting with sensitive DNA hybridizations. A 13-fold amplification of the viral DNA sequences (SV40) and a twofold amplification of two cellular oncogenes of the ras-family (Ki-ras and Ha-ras) were found. Other cellular genes, like the α-actin gene, were not amplified, and no variation in gene copy number was detected after incubation of cells with cold I-UdR. We suggest the observed gene amplifications are induced by the densely ionizing radiation emitted by the decay of the incorporated125I atoms.