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@ARTICLE{Dahmen:808536,
author = {Dahmen, Volker and Pomplun, Ekkehard and Kriehuber, Ralf},
title = {{I}odine-125-labeled {DNA}-{T}riplex-forming
oligonucleotides reveal increased cyto- and genotoxic
effectiveness compared to {P}hosphorus-32},
journal = {International journal of radiation biology},
volume = {92},
number = {11},
issn = {0955-3002},
address = {London},
publisher = {Taylor $\&$ Francis},
reportid = {FZJ-2016-02274},
pages = {679-685},
year = {2016},
abstract = {PURPOSE: The efficacy of DNA-targeting radionuclide
therapies might be strongly enhanced by employing short
range particle-emitters. However, the gain of effectiveness
is not yet well substantiated. We compared the Auger
electron emitter I-125 to the ß--emitter P-32 in terms of
biological effectiveness per decay and radiation dose when
located in the close proximity to DNA using DNA
Triplex-forming oligonucleotides (TFO). The clonogenicity
and the induction of DNA double-strand breaks (DSB) were
investigated in SCL-II cells after exposure to P-32- or
I-125-labeled TFO targeting the glyceraldehyde 3-phosphate
dehydrogenase (GAPDH) gene and after external homogeneous
exposure to gamma-rays as reference radiation.MATERIALS AND
METHODS: TFO were labeled with P-32 or I-125 using the
primer extension method. Cell survival was analyzed by
colony-forming assay and DNA damage was assessed by
microscopic quantification of protein 53 binding protein 1
(53BP1) foci in SCL-II cells.RESULTS: I-125-TFO induced a
pronounced decrease of cell survival (D37 at ∼360
accumulated decays per cell, equivalent to 1.22 Gy cell
nucleus dose) and a significant increase of 53BP1 foci with
increasing decays. The P-32-labeled TFO induced neither a
strong decrease of cell survival nor an increase of 53BP1
foci up to ∼4000 accumulated decays per cell, equivalent
to ∼1 Gy cell nucleus dose. The RBE for I-125-TFO was in
the range of 3-4 for both biological endpoints.CONCLUSIONS:
I-125-TFO proved to be much more radiotoxic than P-32-TFO
per decay and per unit dose although targeting the same
sequence in the GAPDH gene. This might be well explained by
the high number of low energy Auger electrons emitted by
I-125 per decay, leading to a high ionization density in the
immediate vicinity of the decay site, probably producing
highly complex DNA lesions overcharging DNA repair
mechanisms.},
cin = {S-US},
ddc = {570},
cid = {I:(DE-Juel1)S-US-20090406},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000388629800010},
doi = {10.3109/09553002.2016.1160157},
url = {https://juser.fz-juelich.de/record/808536},
}