ABSTRACT
Objective@#To explore the functions of DNA-PKcs in cellular low dose hyper-radiosensitivity.@*Methods@#Colony-formation assay was used to detect the survival fractions of M059K and M059J cell lines treated by X-ray irradiation. Micronucleus assay and γ-H2AX foci assay were used to measure the radiation-induced DNA damage. Western blot was used to detect the relative expression levels of phospho-Chk1, total Chk1, phospho-Chk2 and total Chk2 of M059K and M059J cells.@*Results@#The hyper-radiosensitivity was observed in M059K cells irradiated with X-ray of doses lower than 1 Gy. DNA damage levels did not show HRS/IRR in the cell lines we used. pChk1/Chk1 in M059K cells was significantly increased during 20 min to 60 min after 0.2 Gy X-ray irradiation (t=14.157, 13.661, 14.177, 11.317, 14.512, P<0.05); pChk2/Chk2 in M059K cells was markedly increased during 20 min to 50 min after 0.2 Gy X-ray irradiation (t=13.182, 13.868, 14.155, 14.477, P<0.05).@*Conclusions@#M059K cells show the phenomenon of low dose hyper-radiosensitivity, which may be related to activation of proteins in G2/M phase checkpoints regulated by DNA-PKcs.
ABSTRACT
Objective To establish a model to predict the cell-cycle process in response to ionizing radiation.Methods Human choroidal malignant melanoma 92-1 cells were used and the cell cycle distribution of cells was analyzed in 0-96 h after exposure to X-rays.A phenomenological model was constructed based on biological knowledge to describe the cell cycle dynamics in experiments.Results In the present study,a phenomenological model was constructed to describe the cellcycle dynamics of synchronized 92-1 cells in responding to various doses of ionizing radiation.The simulation results obtained with the model were consistent with the experimental data,demonstrating that the model had a good expansibility and could be used to predict the dynamics of cell cycle in responding to ionizing radiation.Further theoretical modeling of the cellcycle dynamics was made and the results were consistent with the simulation.Conclusions A phenomenological model was constructed which could be used to describe the dynamics of cell cycle of cells exposed to ionizing radiation and was supported by the experimental data.Because this model is easy to run by the written code,it has a good expansibility for studying the behaviors of cell populations under various conditions.