The scoring scale for the percentage of positive

cells was: 0, less than 1%; 1, 1 – 24%; 2, 25 – 50%; 3, 51 – 75%; 4, more than 75%. The scoring scale for staining intensity was: 0, no color; 1, bright yellow; 2, yellow; 3, brown yellow; Kinase Inhibitor Library cell assay 4, brown. The final score was obtained by multiplying the percentage of positive cells by the staining intensity score. Statistical analysis All data were plotted as mean ± standard deviation. Statistical analysis was performed with SPSS 13.0 software. (SPSS Inc., Chicago, IL). Student’s t test was used for comparisons. check details Differences were considered significant when the P was less than 0.05. Results The continuous and low-energy 125I seed irradiation-induced cell apoptosis The red region in the lower left quadrant and right quadrant represented the survival and apoptosis of cells, respectively. The red region area in lower quadrant in 2 Gy group was slightly bigger than that in 0 Gy group (Figure 2A and 2B). The percentage of apoptotic cells (3.15 ± 0.38%) in

2 Gy group was slightly more than that in 0Gy group (1.78 ± 1.01%) (P < 0.05) (Figure 2D). More importantly, CP-690550 the 4 Gy group exhibited a significantly expanded red area relative to the 2Gy and 0 Gy group (Figure 2A, B and 2C). The percentage of apoptotic cells was substantially more in 4Gy group (8.47 ± 0.96%) than in 2 Gy or 0 groups. (P < 0.01) (Figure 2D). Quantitative measurements of apoptotic cell suggested that apoptosis is an important mechanism of low-energy 125I seed irradiation inhibition of SW-1990 cancer cells. Figure 2 Apoptosis of 125 I irradiated SW-1990 cells. The red region in the lower left quadrant represents apoptosis detected by flow cytometry in the 0 Gy (A), 2 Gy (B), and 4 Gy (C) groups. The quantitation is shown in D. *P < 0.05 compared with the 0 Gy (Control) group. # P < 0.05 Sinomenine compared with the 2 Gy group. Expression changes of DNMTs in SW-1990 cells after 125I seed irradiation Expression of DNMT1 (2.91 ± 0.5) and DNMT3b (2.31 ± 0.54) mRNA in the 2 Gy group was significantly higher than in the 0 Gy group (1.29 ± 0.33 and 1.56 ± 0.36, P < 0.05; Figure 3A and 3B). Conversely,

the 4 Gy group exhibited a significant decrease in DNMT1 expression (1.45 ± 0.70) and DNMT3b (0.90 ± 0.25) mRNA compared with the 2 Gy group (P < 0.05; Figures 3A and 3B). More importantly, DNMT3b expression was lower in the 4 Gy group (0.90 ± 0.25) than in the 0 Gy group (1.56 ± 0.36, P < 0.05; Figure 3B). Moreover, DNMT3a mRNA expression did not differ among the three groups (Figure 3C). These data suggest that 125I seed irradiation significantly affects the expression of DNMT1 and DNMT3a mRNA. Figure 3 125 I irradiation induced expression changes of DNA methyltransferases mRNA in SW-1990 cells. DNMT1 (A), DNMT3a (B), and DNMT3b (C) mRNA expression in 125I irradiated SW-1990 cells was detected as described in the Materials and Methods section. *P < 0.