title: Adaptive response to gamma radiation in mammalian cells proficient and deficient in components of nucleotide excision repair.
abstract: Cells preconditioned with low doses of low-linear energy transfer (LET) ionizing radiation become more resistant to later challenges of radiation. The mechanism(s) by which cells adaptively respond to radiation remains unclear, although it has been suggested that DNA repair induced by low doses of radiation increases cellular radioresistance. Recent gene expression profiles have consistently indicated that proteins involved in the nucleotide excision repair pathway are up-regulated after exposure to ionizing radiation. Here we test the role of the nucleotide excision repair pathway for adaptive response to gamma radiation in vitro. Wild-type CHO cells exhibited both greater survival and fewer HPRT mutations when preconditioned with a low dose of gamma rays before exposure to a later challenging dose. Cells mutated for ERCC1, ERCC3, ERCC4 or ERCC5 did not express either adaptive response to radiation; cells mutated for ERCC2 expressed a survival adaptive response but no mutation adaptive response. These results suggest that some components of the nucleotide excision repair pathway are required for phenotypic low-dose induction of resistance to gamma radiation in mammalian cells.
authors.affiliation: Department of Radiation Oncology, UCLA School of Medicine and Public Health, Los Angeles, CA 90095, USA. khafer@mednet.ucla.edu
authors.forename: Kurt
authors.initials: K
authors.lastname: Hafer
authors.forename: Keisuke S
authors.initials: KS
authors.lastname: Iwamoto
authors.forename: Keisuke K
authors.initials: KK
authors.lastname: Iwamoto
authors.forename: Zorica
authors.initials: Z
authors.lastname: Scuric
authors.forename: Robert H
authors.initials: RH
authors.lastname: Schiestl
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D016466:CHO Cells; D002453:Cell Cycle / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects*; D006224:Cricetinae; D003412:Cricetulus; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics; D004720:Endonucleases / Q000235:genetics; D005720:Gamma Rays; D009154:Mutation; D011836:Radiation Tolerance; D051759:Xeroderma Pigmentosum Group D Protein / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; C071447:ERCC1 protein, human; D004720:Endonucleases; D051759:Xeroderma Pigmentosum Group D Protein; C497292:ERCC2 protein, human