Relationship between radiation induced adaptive response in human fibroblasts and changes in chromatin conformation.
Chromatin conformation changes in the normal human fibroblasts VH-10 were studied by the method of anomalous viscosity time dependence (AVTD). Gamma-irradiation of cells in a dose range of 0.1-3 Gy caused an increase in maximal viscosity of cell lysates. Conversely, irradiation of cells with low doses of 0.5 or 2 cGy resulted in a decrease in the AVTD peaks with a maximum effect approximately 40 min after irradiation. The same exposure conditions were used to study a possible adaptive effect of low doses, measured by changes in cell survival. A primary dose of 2 cGy caused significant modification of cell response to a challenge dose. Approximately 20% protection to challenge doses of 0.5 Gy (p < 0.003), 2 Gy (p < 0.02) and 2.5 Gy (p < 0.002) was observed. However, the direction of this effect (adaptation or synergism) was found to be dependent on a challenge dose. The combined effect of 2 cGy and 1 Gy was significantly synergistic, while no modification was observed for 1.5 Gy and 3 Gy. A partial correlation was found between the AVTD changes and cell survival when the combined effect of a primary dose of 2 cGy and challenge dose was examined. The dose of 2 cGy alone increased survival by 16% (p < 0.0003). These results suggest that the low-dose induced effects on survival may be related to chromatin reorganization.
Belyaev IYa
Department of Radiation Physics, Biophysics and Ecology, Moscow Engineering Physics Institute, Russia. belyaev@indep.mepi.msk.su
Spivak
I M
IM
Kolman
A
A
Harms-Ringdahl
M
M
D000222:Adaptation, Physiological / Q000528:radiation effects*; D016923:Cell Death / Q000528:radiation effects; D002478:Cells, Cultured; D002843:Chromatin / Q000737:chemistry / Q000528:radiation effects*; D003114:Colony-Forming Units Assay; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000166:cytology / Q000528:radiation effects*; D005720:Gamma Rays; D006801:Humans; D011487:Protein Conformation; D013997:Time Factors; D014783:Viscosity / Q000528:radiation effects
D002843:Chromatin