The multi-target, single-hit model was applied to calculate cellular radiosensitivity (mean lethal dose, D0), capacity for sublethal damage repair (quasithreshold dose, Dq), and extrapolation number (N). The D10values were used to calculate the relative biological effect (RBE). Cell cycle and

apoptosis analysis Cells from the control and CLDR-treated groups were exposed to different radiation dosages (0, 2, 5, and 10 Gy). Cells were harvested 48 h after irradiation. For detection of apoptotic cells, cells were trypsinized, acridine orange PRT062607 purchase stained, and determined under fluorescence microscope. At the same time, cells were counted and washed twice with cold PBS. Cells used for apoptosis tests were stained with propidium iodide (PI) and annexin V for 15 min in the dark. Cells used for cell-cycle testing were stained with propidium iodide after ethanol fixation and analyzed by fluorescence-activated cell sorting (FACS) using Coulter EPICS and ModFit selleck chemicals llc software (Verity Software House, Topsham, MN). Each test was performed 3 times [19]. EGFR and Raf quantifications by FCM Control and treated CL187 cells for EGFR and Raf quantifications by FCM were harvested 24 h after 4 Gy irradiation. Each test was performed 3 times. Cells used for tests were stained with Phospho-P38 EGFR mAb (Alexa Fluor) and Phospho-raf mAb (Alexa Fluor), and then analyzed by FACScan using Coulter EPICS and ModFit software. Each test

was performed 3 times [20–22]. Statistical analysis Data were plotted as ADP ribosylation factor means ± standard deviation. Student’s t test was used for comparisons. Differences were considered significant at P < 0.05. Results Survival curve of CL187 cells www.selleckchem.com/products/ulixertinib-bvd-523-vrt752271.html after different dose rate irradiation Data showed that cell-killing effects were related to dose rate. The survival curve of CL187 cells after different dose rate irradiation is shown in Figure 2. At the same dose, the survival fractions of125I seeds were always lower than60Co γ ray (Table 1). The cloning efficiency of CL187

was between 70% and 90%. Radiobiological parameters of high dose rate irradiation treated CL187 cells were D0 = 1.85, Dq = 0.35, and N = 1.55, while those of125I seed low dose rate irradiation cells were D0 = 1.32, Dq = 0.14, and N = 1.28. In the present study, RBE = D10 60Co/D10 125I = 4.23/3.01 = 1.41. The data presented herein suggested that the biological effect of125I seed irradiation was stronger than that of60Co γ ray (t = 2.578, P < 0.05). Figure 2 Dose-survival curves of CL187 cells after high and low dose rate irradiation. Table 1 Survival fraction of different dose rate irradiation in CL187 cell line (%, ± s)   Irradiation dose (Gy)   1 2 4 6 8 10 Survival fraction 60Co 73 ± 22 49 ± 11 17 ± 5.2 5.7 ± 2.1 1.8 ± 0.19 0.74 ± 0.21 125I 55 ± 18a 28 ± 10b 5.2 ± 2.7c 1.3 ± 0.25d 0.33 ± 0.12e 0.08 ± 0.03f Compared with60Co group, t = 8.03,aP < 0.05; t = 4.85,bP < 0.05; t = 13.69,cP < 0.01; t = 11.43,dP < 0.01; t = 4.76,eP < 0.05; and t = 4.62,fP < 0.05.