Purpose: We have Shown that, ionizing radiation increases recombination, as
manifested by increased Stable transduction of both plasmid and adenoviral
vectors. This paper reports the duration of increased recombination after
Materials and methods: A549 or NIH/3T3 cells were transfected at various ti
mes after irradiation. Cells were also irradiated with several fractionatio
n schemes and then transfected.
Results: Enhanced integration (El) is a very long-lived process, lasting at
least 2-3 days after single radiation fractions. The duration of EI activa
tion is radiation dose-dependent. The efficiency of EI is dependent on radi
ation close and independent of fractionation, such that low close-rate, fra
ctionated and single radiation doses result in similar levels of EI when co
rrected for differences in cytotoxicity.
Conclusions: Radiation, given with fraction sizes and dose-rates used in cl
inical radiation therapy, induces a Ion-lived hyper-recombination state, Si
nce radiotherapy is already a component of treatment for many malignancies
and is integrated into radiation-gene therapy trials, an understanding of r
ecombination events that. improve gene delivery is important and timely.