Association of ATM activation and DNA repair with induced radioresistance after low-dose irradiation

L. Enns, A. Rasouli-Nia, M. Hendzel, Brian Marples, M. Weinfeld

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Mammalian cells often exhibit a hyper-radiosensitivity (HRS) to radiation doses <20 cGy, followed by increased radioresistance (IRR) at slightly higher doses (~20-30 cGy). Here, the influence of DNA double-strand break repair (DSBR) on IRR was examined. The failure of Ataxia telangiectasia (AT) cells to undergo IRR reported by others was confirmed. Flow cytometric analysis indicated that normal cells fail to show a measurable increase in serine 1981 phosphorylated AT-mutated (ATM) protein after 10 cGy up to 4 h post irradiation, but a two- to fourfold increase after 25 cGy. Similarly, more proficient reduction of phosphorylated histone H2AX was observed 24 h after 25 cGy than after 10 cGy, suggesting that DSBR is more efficient during IRR than HRS. A direct examination of the consequences of inefficient DNA repair per se (as opposed to ATM-mediated signal transduction/cell cycle responses), by determining the clonogenic survival of cells lacking the DNA repair enzyme polynucleotide kinase/phosphatase, indicated that these cells have a response similar to AT cells, i.e. HRS but no IRR, strongly linking IRR to DSBR.

Original languageEnglish (US)
Article numberncv203
Pages (from-to)131-136
Number of pages6
JournalRadiation Protection Dosimetry
Volume166
Issue number1-4
DOIs
StatePublished - Jan 1 2015
Externally publishedYes

ASJC Scopus subject areas

  • Radiation
  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging
  • Public Health, Environmental and Occupational Health

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