Radiation-induced chromosomal instability in BALB/c and C57BL/6 mice: the difference is as clear as black and white

Radiat Res. 1997 Feb;147(2):121-5.

Abstract

Genomic instability has been proposed to be the earliest step in radiation-induced tumorigenesis. It follows from this hypothesis that individuals highly susceptible to induction of tumors by radiation should exhibit enhanced radiation-induced instability. BALB/c white mice are considerably more sensitive to radiation-induced mammary cancer than C57BL/6 black mice. In this study, primary mammary epithelial cell cultures from these two strains were examined for the "delayed" appearance of chromosomal aberrations after exposure to 137Cs gamma radiation, as a measure of radiation-induced genomic instability. As expected, actively dividing cultures from both strains showed a rapid decline of initial asymmetrical aberrations with time postirradiation. However, after 16 population doublings, cells from BALB/c mice exhibited a marked increase in the frequency of chromatid-type breaks and gaps which remained elevated throughout the time course of the experiment (28 doublings). No such effect was observed for the cells of C57BL/6 mice; after the rapid clearance of initial aberrations, the frequency of chromatid-type aberrations in the irradiated population remained at or near those of nonirradiated controls. These results demonstrate a correlation between the latent expression of chromosomal damage in vitro and susceptibility for mammary tumors, and provide further support for the central role of radiation-induced instability in the process of tumorigenesis.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Transformation, Neoplastic / radiation effects
  • Cells, Cultured
  • Chromatids / radiation effects
  • Chromatids / ultrastructure
  • Chromosome Aberrations*
  • Chromosomes / radiation effects*
  • Chromosomes / ultrastructure
  • DNA Repair / genetics
  • Disease Susceptibility
  • Epithelium / radiation effects
  • Epithelium / ultrastructure
  • Female
  • Gamma Rays / adverse effects*
  • Mammary Glands, Animal / radiation effects*
  • Mammary Glands, Animal / ultrastructure
  • Mammary Neoplasms, Experimental / genetics*
  • Mice
  • Mice, Inbred BALB C / genetics*
  • Mice, Inbred C57BL / genetics*
  • Neoplasms, Radiation-Induced / genetics*
  • Radiation Tolerance / genetics*