Decay of γ-H2AX foci correlates with potentially lethal damage repair and P53 status in human colorectal carcinoma cells

Cell Mol Biol Lett. 2014 Mar;19(1):37-51. doi: 10.2478/s11658-013-0113-0. Epub 2013 Dec 23.


The influence of p53 status on potentially lethal damage repair (PLDR) and DNA double-strand break (DSB) repair was studied in two isogenic human colorectal carcinoma cell lines: RKO (p53 wild-type) and RC10.1 (p53 null). They were treated with different doses of ionizing radiation, and survival and the induction of DNA-DSB were studied. PLDR was determined by using clonogenic assays and then comparing the survival of cells plated immediately with the survival of cells plated 24 h after irradiation. Doses varied from 0 to 8 Gy. Survival curves were analyzed using the linear-quadratic formula: S(D)/S(0) = exp-(αD+βD(2)). The γ-H2AX foci assay was used to study DNA DSB kinetics. Cells were irradiated with single doses of 0, 0.5, 1 and 2 Gy. Foci levels were studied in non-irradiated control cells and 30 min and 24 h after irradiation. Irradiation was performed with gamma rays from a (137)Cs source, with a dose rate of 0.5 Gy/min. The RKO cells show higher survival rates after delayed plating than after immediate plating, while no such difference was found for the RC10.1 cells. Functional p53 seems to be a relevant characteristic regarding PLDR for cell survival. Decay of γ-H2AX foci after exposure to ionizing radiation is associated with DSB repair. More residual foci are observed in RC10.1 than in RKO, indicating that decay of γ-H2AX foci correlates with p53 functionality and PLDR in RKO cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Survival / genetics*
  • Cell Survival / radiation effects
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / pathology
  • DNA Breaks, Double-Stranded / radiation effects
  • DNA Damage / radiation effects
  • DNA Repair / genetics
  • DNA Repair / radiation effects
  • Histones / genetics*
  • Histones / metabolism
  • Humans
  • Radiation, Ionizing
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*


  • H2AX protein, human
  • Histones
  • TP53 protein, human
  • Tumor Suppressor Protein p53