Chromatin- and temperature-dependent modulation of radiation-induced double-strand breaks

• Purpose: To investigate the influence of chromatin organization and scavenging capacity in relation to irradiation temperature on the induction of double-strand breaks (DSB) in structures derived from human diploid fibroblasts. Materials and methods: Agarose plugs with different chromatin structures (intact cells±wortmannin, permeabilized cells with condensed chromatin, nucleoids and DNA) were prepared and irradiated with X-rays at 2 or 37°C and lysed using two different lysis protocols (new ice-cold lysis or standard lysis at 37°C). Induction of DSB was determined by constant-field gel electrophoresis. Results: The dose-modifying factor (DMFtemp) for irradiation at 37 compared with 2°C was 0.92 in intact cells (i.e. more DSB induced at 2°C), but gradually increased to 1.5 in permeabilized cells, 2.2 in nucleoids and 2.6 in naked DNA, suggesting a role of chromatin organization for temperature modulation of DNA damage. In addition, DMFtemp was influenced by the presence of 0.1 M DMSO or 30 mM glutathione, but not by post-irradiation temperature. Conclusion: The protective effect of low temperature was correlated to the indirect effects of ionizing radiation and was not dependent on post-irradiation temperature. Reasons for a dose modifying factor <1 in intact cells are discussed.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

Nyckelord

dimethyl sulfoxide

glutathione

naked DNA

wortmannin

article

chromatin

controlled study

correlation analysis

diploidy

DNA damage

DNA strand breakage

fibroblast

gel electrophoresis

human

human cell

lysis

priority journal

radiation exposure

regulatory mechanism

temperature dependence

X ray

Androstadienes

Cell Line

Cryopreservation

DNA

Dose-Response Relationship

Radiation

Fibroblasts

Humans

Radiation Dosage

Radiation Protection

Relative Biological Effectiveness

Temperature

Androstadienes/pharmacology

Cell Line

Chromatin/*radiation effects

Cryopreservation/methods

DNA/drug effects/*radiation effects

*DNA Damage

*Dose-Response Relationship

Radiation

Fibroblasts/*radiation effects

Humans

Radiation Dosage

Radiation Protection/methods

Relative Biological Effectiveness

*Temperature

MEDICINE

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)