3). FCM analysis showed that under low dose rate irradiation, apoptosis and G2/M cell cycle arrest increased slightly at 2 Gy, the peak appeared at 5 Gy, and the ratio was also high at 10 Gy (Table 2) but lower than that at 5 Gy. Furthermore, G2/M cell cycle arrest and apoptosis walked together along with the dose change (r = 0.918, P < 0.01, Fig. 4). Quantitative measurements of apoptotic GSK126 cell death by FCM in CL187 cells sufficiently indicated that apoptosis

is an important mechanism of low dose rate irradiation inhibition of CL187 cell proliferation. Figure 3 Apoptosis of 125 I low dose rate irradiation-treated CL187 cells. CL187 cells were stained with acridine orange, and determined under fluorescence microscope. There were no apoptotic cells in control groups (A), but typical morphological features of apoptosis appeared after 5 Gy CLDR irradiation (B). The apoptotic rates were detected by flow cytometry.

In 2 Gy (D), 5 Gy (E), and 10 Gy (F) groups, the CL187 cells had higher apoptosis rates when compared with control groups (C). Concrete data see table 3. One of three experiments is shown. P < 0.05 vs. control group were found in every treated groups. Figure 4 Effect of 125 I low dose rate irradiation on the cell cycle in CL187 cells. Flow cytometry analysis revealed APO866 chemical structure that the G2/M phase increased by 2 Gy (B)125I irradiation dose as compared with untreated control cells (A). After 5 Gy irradiation (C), a sharp increase in the fraction of cells in the G2/M phase was observed. The result in 10 Gy irradiation groups (D) was lower than that in group C, but sustained at a relatively Nintedanib in vivo high level. Compared with untreated control cells, P < 0.05 were found in all

of the treated groups. Table 2 Apoptosis index and cell cycle distribution after125I low dose rate irradiation (%, ± s).   Apoptosis G0/G1 S G2/M Control 1.67 ± 0.19 64.94 ± 5.87 8.62 ± 0.59 26.44 ± 2.53 2 Gy 13.74 ± 1.63a 54.14 ± 3.16 11.25 ± 1.34 34.61 ± 2.79d 5 Gy 46.27 ± 3.82b 26.60 ± 2.82 13.56 ± 1.68 59.84 ± 4.96e 10 Gy 32.58 ± 3.61c 41.69 ± 4.58 15.72 ± 2.29 42.59 ± 3.21f Compared with control group (apoptosis), t = 8.377,aP < 0.05; t = 36.44,bP < 0.01; and t = 27.35,cP < 0.01. Compared with control group (G2/M arrests), t = 30.81,dP < 0.05; t = 23.98,dP < 0.05; and t = 26.3,eP < 0.05. Expression changes of EGFR and Raf in CL187 cells after irradiation and/or EGFR monoclonal antibody treatment Under low dose rate irradiation, expression of EGFR (74.27 ± 5.63%) and Raf (53.84 ± 2.31%) was significantly higher than in the control group (Fig. 5 and Table 3). After signal transduction was blocked, expression of EGFR (2.07 ± 0.31%) and Raf (13.74 ± 1.82%) did not show detectable change after low dose rate irradiation (Fig. 5 and Table 3).