DECAY OF gamma-H2AX FOCI CORRELATES WITH POTENTIALLY LETHAL DAMAGE REPAIR AND P53 STATUS IN HUMAN COLORECTAL CARCINOMA CELLS

作者：Van Oorschot Bregje; Oei Arlene L; Nuijens Anna C; Rodermond Hans; Hoeben Ron; Stap Jan; Stalpers Lukas J; Franken Nicolaas A P^*

来源：Cellular and Molecular Biology Letters, 2014, 19(1): 37-51.

DOI：10.2478/s11658-013-0113-0

• p53
• Radiation sensitivity
• Potentially lethal damage repair (PLDR)
• Linear-quadratic model
• Clonogenic assay
• Colon cancer cells
• RKO cells
• RC10.1 cells
• gamma-H2AX foci
• Flow cytometry

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-(alpha D+beta D-2). The gamma-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 Cs-137 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 gamma-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 gamma-H2AX foci correlates with p53 functionality and PLDR in RKO cells.

• 出版日期2014-3