Images of cells taken at 0, 48, and 72 hours after scratching in wound healing assays; quantitative analysis indicated that a single irradiation dose of 2, 4, or 6 Gy inhibited cell migration. rates in the terminal deoxynucleotidyl transferaseCmediated 2-deoxyuridine 5-triphosphate nick-end labeling assay (.05). In Transwell assessments, the 4 Gy and 6 Gy groups experienced fewer invading cells than the control group ( .05). Single-dose irradiation of 6 Gy with the Intrabeam device can effectively inhibit proliferation, migration, and invasiveness and promote apoptosis in MCF-7 cells with long-lasting effects. .05 was considered significant. The multitarget click model of GraphPad Prism 5.0 (Systat Software, Inc, San Jose, California) was used to generate the cell survival curve. Results Single-Dose Irradiation With the Intrabeam Inhibited Cell Proliferation Colony formation assays indicated that this QS 11 MCF-7 cells in the control group were in logarithmic division, with colony-like distribution. In the experimental groups (especially those that experienced received doses of 6 Gy), cell proliferation became much slower, most of the cells DHRS12 swelled, fewer mitotic cells were seen, and cell communities were unevenly distributed. In the control samples, the average quantity of positive clones was 246 (PE = 24.6%). As the radiation dose increased, the numbers of positive clones greatly decreased; no positive clone was found in the groups with doses of 6 Gy. The cell survival curve fitted by positive clone figures is shown in Physique 1. Open in a separate window Physique 1. Cell survival curve for MCF-7 QS 11 cells irradiated by the Intrabeam device (50 kV X-ray source) with a flat applicator. Adherent cells in T-25 flasks were irradiated at a constant dose rate of 14.8 Gy/h. Results show the mean of 3 impartial experiments. Single-Dose Irradiation With the Intrabeam Induced Apoptosis/Necrosis and G1 Phase Arrest at 24 Hours After Treatment MCF-7 apoptosis was detected by Annexin V-FITC/PI staining (Physique 2A and B). One-way ANOVA indicated that this late apoptosis/necrosis ratios were greater in the 2 2 Gy (.003), 4 Gy (.001), and 6 Gy (.001) groups than in the control group. The unfavorable rates in the 4 Gy (.003) and 6 Gy (.037) groups were significantly lower than in the control group. However, there were no significant differences in the early apoptosis ratios between the experimental and control groups (.05). Open in a QS 11 separate window Physique 2. Circulation cytometry Annexin V-FITC/PI apoptosis analyses and cell-cycle analyses of MCF-7 cells 24 hours after single-dose irradiation with the Intrabeam device. A, Intact viable cells (lower left), early apoptotic cells (lower right), and late apoptotic or necrotic QS 11 cells (upper right). B and D, Data are expressed as mean SD; *.05, **.01 (vs control group); results show the mean of 3 impartial experiments. PI indicates propidium iodide; SD, standard deviation. The circulation cytometry results for cell-cycle distribution are shown in Physique 2C and D. Greater numbers of cells were stagnated in G1 phase in each experimental group compared with the control group (all values were .01). Single-Dose Irradiation With the Intrabeam Inhibited Migration and Invasion and Promoted Apoptosis 4 Weeks After Treatment Wound healing assays indicated that this width of scratches were gradually reduced (Physique 3A). Multiple comparisons of the 72 hour-scratch repair rates (Physique 3C) indicated that this rates in the experimental groups were significantly lower than in the control group (all values were .001; 1-way ANOVA). The rate of the 6 Gy group was significantly lower than the 2 2 Gy (.002) and 4 Gy groups (.003). Open in a separate window Physique 3. MCF-7 cell migration, invasion, and apoptosis assessments 4 weeks after single-dose irradiation by the Intrabeam device. Each experiment was repeated 3 times. A and C, Wound healing assays. Images of cells taken at 0, 48, and 72 hours after scratching in wound healing assays; quantitative analysis indicated that a single irradiation dose of 2, 4, or 6 Gy inhibited cell migration. D, Transwell assay indicated that a single irradiation dose of 4 or 6 Gy inhibited cell invasion. B and E, TUNEL apoptosis assay indicated that a single irradiation dose of 2, 4, or 6 Gy promoted cell apoptosis. Green: TUNEL-positive apoptotic cells; blue: nuclei stained with 4,6-diamidino-2-phenylindole (DAPI); magnification 100. C.