Abstract
The risk of a large-scale event leading to acute radiation
exposure necessitates the development of high-throughput
methods for providing rapid individual dose estimates. Our
work addresses three goals, which align with the directive of
the European Union’s Realizing the European Network of
Biodosimetry project (EU-RENB): 1. To examine the
suitability of different gene expression platforms for biodosimetry
purposes; 2. To perform this examination using
blood samples collected from prostate cancer patients (in
vivo) and from healthy donors (in vitro); and 3. To compare
radiation-induced gene expression changes of the in vivo with
in vitro blood samples. For the in vitro part of this study,
EDTA-treated whole blood was irradiated immediately after
venipuncture using single X-ray doses (1 Gy/min1 dose rate,
100 keV). Blood samples used to generate calibration curves
as well as 10 coded (blinded) samples (0–4 Gy dose range)
were incubated for 24 h in vitro, lysed and shipped on wet ice.
For the in vivo part of the study PAXgene tubes were used
and peripheral blood (2.5 ml) was collected from prostate
cancer patients before and 24 h after the first fractionated 2
Gy dose of localized radiotherapy to the pelvis [linear
accelerator (LINAC), 580 MU/min, exposure 1–1.5 min].
Assays were run in each laboratory according to locally
established protocols using either microarray platforms (2 laboratories) or qRT-PCR (2 laboratories). Report times on
dose estimates were documented. The mean absolute difference
of estimated doses relative to the true doses (Gy) were
calculated. Doses were also merged into binary categories
reflecting aspects of clinical/diagnostic relevance. For the in
vitro part of the study, the earliest report time on dose
estimates was 7 h for qRT-PCR and 35 h for microarrays.
Methodological variance of gene expression measurements
(CV 10% for technical replicates) and interindividual
variance (twofold for all genes) were low. Dose estimates
based on one gene, ferredoxin reductase (FDXR), using qRTPCR
were as precise as dose estimates based on multiple
genes using microarrays, but the precision decreased at doses
2 Gy. Binary dose categories comprising, for example,
unexposed compared with exposed samples, could be
completely discriminated with most of our methods. Exposed
prostate cancer blood samples (n ¼ 4) could be completely
discriminated from unexposed blood samples (n ¼ 4, P ,
0.03, two-sided Fisher’s exact test) without individual
controls. This could be performed by introducing an in
vitro-to-in vivo correction factor of FDXR, which varied
among the laboratories. After that the in vitro-constructed
calibration curves could be used for dose estimation of the in
vivo exposed prostate cancer blood samples within an
accuracy window of 60.5 Gy in both contributing qRTPCR
laboratories. In conclusion, early and precise dose
estimates can be performed, in particular at doses 2 Gy in
vitro. Blood samples of prostate cancer patients exposed to
0.09–0.017 Gy could be completely discriminated from preexposure
blood samples with the doses successfully estimated
using adjusted in vitro-constructed calibration curves.
Details
Original language | English |
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Pages (from-to) | 109-123 |
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Journal | Radiation Research |
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Volume | 185 |
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Issue number | 2 |
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DOIs | |
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Publication status | Published - 1 Feb 2016 |
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