Cell-free DNA in the urine of rats exposed to ionizing radiation

Abstract

Investigation of cell-free DNA (cf-DNA) in body fluids, as a potential biomarker for assessing the effect of ionizing radiation on the organism, is of considerable interest. We investigated changes in the contents of cell-free mitochondrial DNA (cf-mtDNA) and cell-free nuclear DNA (cf-nDNA) in the urine of X-ray-exposed rats. Assays of cf-mtDNA and cf-nDNA were performed by a real-time PCR in rat urine collected before and after irradiation of animals with doses of 3 and 5 Gy. We also determined the presence of mutations in urine cf-mtDNA, as recognized by Surveyor nuclease. A sharp increase in cf-mtDNA and cf-nDNA in the urine of irradiated rats was observed within 24 h after exposure, followed by a decrease to normal levels. In all cases, the contents of cf-mtDNA fragment copies (estimated by gene tRNA) were significantly higher than those of cf-nDNA estimated by gene GAPDH. A certain portion of mutant cf-mtDNA fragments was detected in the urine of exposed rats, whereas they were absent in the urine of the same animals before irradiation. These preliminary data also suggest that the increased levels of urine cf-mtDNA and cf-nDNA may be a potential biomarker for noninvasive assessment of how the organism responds to ionizing radiation influence.

The Molecular Mechanisms in Senescent Cells Induced by Natural Aging and Ionizing Radiation

“…The use of cf-mtDNA as a biomarker for radiation exposure is of considerable interest. There are data on the appearance of cf-mtDNA in the urine of rats after irradiation, but before IR, they were absent [ 199 ]. Bisserier et al [ 200 ] measured cf-mtDNA levels in the blood plasma of astronauts 10 days before launch, on the day of landing, and 3 days after return and found a significant increase in cf-mtDNA in two cases: on the day of landing and a few days later.…”

Combining Heavy-Ion Therapy with Immunotherapy: An Update on Recent Developments

“…Furthermore, in cancer cells lacking p53 or Rb genes in particular, nuclear rupture is enhanced [43,60]. Interestingly, cell-free circulating dsDNA fragments in body fluids of animals as well as in the plasma of patients undergoing RT has been described and linked with immunostimulation via various mechanisms [61][62][63]. This may be another distinct mechanism of action for particle therapy, if the aforementioned induction of very small dsDNA fragments following high-LET exposure is considered [57,64,65].…”

X-rays and metformin cause increased urinary excretion of cell-free nuclear and mitochondrial DNA in aged rats

“…Notably, the cf-mtDNA increase is much higher than that of cf-nDNA, which suggests the involvement of mitophagy (by autophagic mechanism) in postirradiation cell death. 17 Metformin, as mentioned above, initiates the death of cells containing structural and functional abnormalities by the mechanism of autophagy. The intensification of cell death at the level of a whole mammalian organism can be estimated by a raise in the content of cf-DNA in urine or plasma.…”