M. Kruszewski et al., DNA STRAND BREAKAGE, CYTOTOXICITY AND MUTAGENICITY OF HYDROGEN-PEROXIDE TREATMENT AT 4-DEGREES-C AND 37-DEGREES-C IN L5178Y SUBLINES, MUTATION RESEARCH, 308(2), 1994, pp. 233-241
Cells from the L5178Y murine lymphoma subline LY-R are twofold more re
sistant to killing by ionizing radiation than the subline LY-S. In con
trast, LY-R cells are more sensitive to killing by hydrogen peroxide.
Cells of the two sublines in logarithmic growth phase were treated wit
h hydrogen peroxide in phosphate-buffered saline for 1 h at 4 degrees
C or 37 degrees C. From the comparison of D-o values it followed that
at 37 degrees C LY-R were 3.6 times more sensitive to the killing effe
ct of H2O2 than LY-S cells; at 4 degrees C they were 11 times more sen
sitive. Treatment with hydrogen peroxide at 4 degrees C gave a conside
rable sparing effect, which was substantially greater for the LY-S sub
line; for LY-S cells D, was 5.7 times lower at 37 degrees C than at 4
degrees C, for LY-R cells only 1.9 times. The mutation frequency (HGPR
T) in LY-R cells was increased in proportion to H2O2 concentration and
was the same at both treatment temperatures. In contrast, mutation fr
equencies initially increased, then decreased with increasing H2O2 con
centration in LY-S cells treated at 4 or 37 degrees C. The concentrati
on at which the decline was initiated was higher at 4 than at 37 degre
es C. DNA damage after H2O2 treatment (both temperatures, 5 min) was e
stimated from the 'comet' assay (single-cell gel electrophoresis). The
initial damage, but not the residual damage, differed significantly i
n LY sublines. A period of slower repair (between 3 and 10 min) was fo
und in LY-R cells.