Abstract
The aim of this work was to study radiation-induced bystander
effects for early cytogenetic end points in various cell
lines using the medium transfer technique after exposure to
high- and low-LET radiation. Cells were exposed to 20 MeV/
nucleon nitrogen ions, 968 MeV/nucleon iron ions, or 575
MeV/nucleon iron ions followed by transfer of the conditioned
medium from the irradiated cells to unirradiated test cells.
The effects studied included DNA double-strand break induction,
-H2AX focus formation, induction of chromatid breaks
in prematurely condensed chromosomes, and micronucleus
formation using DNA repair-proficient and -deficient hamster
and human cell lines (xrs6, V79, SW48, MO59K and MO59J).
Cell survival was also measured in SW48 bystander cells using
X rays. Although it was occasionally possible to detect an increase
in chromatid break levels using nitrogen ions and to
see a higher number of -H2AX foci using nitrogen and iron
ions in xrs6 bystander cells in single experiments, the results
were not reproducible. After we pooled all the data, we could
not verify a significant bystander effect for any of these end
points. Also, we did not detect a significant bystander effect
for DSB induction or micronucleus formation in these cell
lines or for clonogenic survival in SW48 cells. The data suggest
that DNA damage and cytogenetic changes are not induced
in bystander cells. In contrast, data in the literature
show pronounced bystander effects in a variety of cell lines,
including clonogenic survival in SW48 cells and induction of
chromatid breaks and micronuclei in hamster cells. To reconcile
these conflicting data, it is possible that the epigenetic
status of the specific cell line or the precise culture conditions
and medium supplements, such as serum, may be critical for
inducing bystander effects.
Original language | English |
---|---|
Journal | Radiation Research |
Volume | 170 |
Pages (from-to) | 794–802 |
ISSN | 0033-7587 |
DOIs | |
Publication status | Published - 2008 |
Externally published | Yes |