[Cellular damage in vitro].
OBJECTIVE
The cellular damage of ionising radiation depends on dose, physical radiation quality (e. g. LET) and intracellular radionuclide uptake. The influence of two beta emitters (188Re and 131I) on the thyroid cell line PCCl3 was studied. Furthermore, we analysed the effect of intracellular accumulation.


METHODS
The thyroid cell line PCCl3 was irradiated with 188Re-perrhenate or 131I-sodium iodide in presence or absence of perchlorate. The initial DNA-damage was measured in the comet assay as olive tail moment (OTM). The colony forming assay detects the clonogenic cell survival as surviving fraction. Additional the intracellular radionuclide uptake was quantified.


RESULTS
Dose response curves were established for irradiation with 188Re-perrhenate or 131I-iodine under various extra- and intracellular activity distribution conditions. In the presence of perchlorate DNA-damage and clonogenic cell survival for both radionuclides were comparable. In the absence of perchlorate radionuclide uptake of 1.39% (131I) and 4.14% (188Re) were measured causing twofold higher radiotoxicity. Although 131I uptake was lower than 188Re uptake the OTM values were higher und surviving fractions were lower.


CONCLUSIONS
131I, compared to 188Re, has lower mean beta energy and a higher LET, and therefore, it induced a higher DNA-damage even at lower intracellular uptake. An additional explanation for the higher radiotoxicity of 131I could be the higher dose exposition caused by cross-fire through neighborhood cells.
Wendisch
M
M
Klinik und Poliklinik für Nuklearmedizin, Universitätsklinikum Dresden, Fetscherstr. 74, 01307 Dresden, Germany. maria.wendisch@uniklinikum-dresden.de
Drechsel
J
J
Freudenberg
R
R
Runge
R
R
Wunderlich
G
G
Kotzerke
J
J
D000818:Animals; D002460:Cell Line; D002477:Cells / Q000473:pathology* / Q000528:radiation effects; D003114:Colony-Forming Units Assay; D020552:Comet Assay; D004247:DNA / Q000528:radiation effects; D004249:DNA Damage; D006801:Humans; D007457:Iodine Radioisotopes / Q000009:adverse effects* / Q000493:pharmacokinetics; D011868:Radioisotopes / Q000009:adverse effects* / Q000493:pharmacokinetics; D051381:Rats; D012211:Rhenium / Q000009:adverse effects* / Q000493:pharmacokinetics; D013961:Thyroid Gland / Q000528:radiation effects*
D007457:Iodine Radioisotopes; D011868:Radioisotopes; D012211:Rhenium; D004247:DNA