Induction of DNA double-strand breaks by ionizing radiation at the c-myc locus compared with the whole genome: a study using pulsed-field gel electrophoresis and gene probing.
Ionizing radiation-induced double-strand breaks (dsb) in a human colon carcinoma-derived cell line COLO320HSR were determined from the fragment size distribution of non-specifically labelled DNA and Sfi I restriction enzyme-digested DNA uniformly labelled with a c-myc probe. The dose-effect relation for the induction of DNA dsb was linear with no significant difference between slopes for the curves in the whole genome (7.2 +/- 0.3 x 10(-9) dsb/bp/Gy) and in the 130 kbp restriction fragments containing c-myc (6.5 +/- 0.5 x 10(-9) dsb/bp/Gy). The size distribution of the c-myc fragments showed deviations from the random-breakage model, indicating heterogeneity of dsb induction at this locus.
Sak
A
A
Department of Radiotherapy, University of Essen, Germany.
Stuschke
M
M
Stapper
N
N
Streffer
C
C
D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage / Q000528:radiation effects*; D016521:Electrophoresis, Gel, Pulsed-Field; D016259:Genes, myc; D006801:Humans; D011839:Radiation, Ionizing; D014407:Tumor Cells, Cultured
D004247:DNA