Gamma-ray and Hydrogen Peroxide Induction of Gene Amplification in Hamster Cells Deficient in DNA Double Strand Break Repair

DNA Repair (Amst). 2002 Jun 21;1(6):483-93. doi: 10.1016/s1568-7864(02)00035-6.


To investigate the role of DNA double strand breaks (DSBs) and of their repair in gene amplification, we analyzed this process in the V3 Chinese hamster cell line and in the parental line AA8, after exposure to gamma-rays and to hydrogen peroxide (H2O2). V3 is defective in DSB repair because of a mutation in the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) gene, a gene involved in the non-homologous end-joining pathway. As a measure of gene amplification we used the frequency of colonies resistant to N-(phosphonacetyl)-L-aspartate (PALA), since in rodent cells PALA resistance is mainly achieved through the amplification of the CAD (carbamyl-P-synthetase, aspartate transcarbamylase, dihydro-orotase) gene. After treatment with different doses of gamma-rays and of H2O2, we found a dose related increase in the frequency of gene amplification and of chromosome aberrations. When the same doses of damaging agents were used, these increments were higher in V3 than in AA8. These results indicate that DSBs that are not efficiently repaired can be responsible for the induction of gene amplification. H2O2 stimulates gene amplification as well as gamma-rays, however, at similar levels of amplification induction, chromosome damage was about 50% lower. This suggests that gene amplification can be induced by H2O2 through pathways alternative to a direct DNA damage. Stimulation of gene amplification by H2O2, which is one of the products of the aerobic metabolism, supports the hypothesis that cellular metabolic products themselves can be a source of genome instability.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antimetabolites, Antineoplastic / pharmacology
  • Aspartic Acid / analogs & derivatives*
  • Aspartic Acid / pharmacology
  • Cell Line
  • Chromosome Aberrations / drug effects
  • Chromosome Aberrations / radiation effects
  • Cricetinae
  • Cricetulus
  • DNA / biosynthesis
  • DNA Damage*
  • DNA Repair / genetics*
  • DNA-Activated Protein Kinase
  • DNA-Binding Proteins*
  • Drug Resistance, Neoplasm
  • Gamma Rays
  • Gene Amplification / drug effects*
  • Gene Amplification / radiation effects*
  • Hydrogen Peroxide / pharmacology*
  • Multienzyme Complexes / genetics
  • Oxidants / pharmacology*
  • Phosphonoacetic Acid / analogs & derivatives*
  • Phosphonoacetic Acid / pharmacology
  • Protein-Serine-Threonine Kinases / deficiency
  • Protein-Serine-Threonine Kinases / genetics


  • Antimetabolites, Antineoplastic
  • DNA-Binding Proteins
  • Multienzyme Complexes
  • Oxidants
  • Aspartic Acid
  • sparfosic acid
  • DNA
  • Hydrogen Peroxide
  • DNA-Activated Protein Kinase
  • Protein-Serine-Threonine Kinases
  • Phosphonoacetic Acid