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@INPROCEEDINGS{Dahmen:837959,
author = {Dahmen, Volker and Reiter, Stefan and Pomplun, Ekkehard and
Kriehuber, Ralf},
title = {{E}nhanced cyto- and genotoxic effects of {A}uger electron
emitter-labeled {DNA}-{T}riplex-forming oligonucleotides in
vitro},
reportid = {FZJ-2017-06720},
year = {2014},
abstract = {The efficacy of DNA-targeting radionuclide therapies might
be strongly enhanced by employing short range
particleemitter.However, the therapeutic use of
radionuclides requests a thorough radiation dosimetry
especially whenshort-range particles are released. In this
study we compared the ß-emitter P-32 and the Auger electron
emitter I-125in terms of biological effectiveness per decay
and per unit dose when located in the close proximity to the
DNA byusing Triplex-forming oligonucleotides (TFO).TFO bind
to the DNA double helix in a sequence specific manner.
Therefore, TFO seem to be a suitable carrier
forradionuclides emitting short-range electrons to damage
exclusively targeted DNA sequences. We
investigatedclonogenicity (colony-forming assay; CFA) in the
human squamous carcinoma cell line II (SCL-II) and the
induction ofDNA double strand breaks (DSB; 53BP1 foci assay)
after exposure with P-32 or I-125 labeled TFO for
differentnumbers of accumulated decays. The employed TFO
targeted a specific DNA sequence located in the
glyceraldehyde3-phosphate dehydrogenase (GAPDH)
gene.Results: I-125-labeled TFO binding to single targets
were shown to induce a pronounced decrease in cell survival
andan increase of DSB with increasing numbers of accumulated
decays per cell. The reduction in cell survival asmeasured
in the CFA reached the D37 value at ~ 350 accumulated decays
per cell, equivalent to ~ 1.2 Gy cellnucleus dose. Using the
same TFO but labeled with P-32 revealed neither a
significant decrease of the survivalfraction nor an increase
of the DSB rate in SCL-II cells up to ~ 4,000 accumulated
decays per cell which is equivalentto ~ 1 Gy cell nucleus
dose.Summary $\&$ Conclusions: The reduction of cell
survival and the increase of DNA damage proved to be much
morepronounced in I-125-TFO transfected cells than observed
after exposure with the P-32-labeled TFO per decay and
perdose unit. This can be 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 very complex
DNAlesions, overcharging the cellular DNA-repair
mechanisms.},
month = {Oct},
date = {2014-10-18},
organization = {27th Annual Congress of the European
Association of Nuclear Medicine and 5th
International Symposium on Targeted
Radionuclide-therapy and Dosimetry,
Göteborg (Schweden), 18 Oct 2014 - 22
Oct 2014},
subtyp = {After Call},
cin = {S-US},
cid = {I:(DE-Juel1)S-US-20090406},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)6},
url = {https://juser.fz-juelich.de/record/837959},
}