| Purposes: To investigate the relationship between irradiation-induced up-regulation of Fas receptor/iNOS expression and apoptosis in human gastric cancer cell lines (SGC?9OIGCC) and the gastric mucosa cells of nude mice and provide some scientific evidence to the hypothesis of radiation-induced apoptosis dependent on the induction of Fas/1NOS after irradiation. Methods:1. In vitro, SGC?9O1GCC were irradiated with single dose of 5Gy lOGy and 2OGy by 6MV X-rays, respectively. By the combination of Annexin V FITC and propidium iodide (P1) staining, apoptotic indexes of l2hour., 24hour and 48hour after irradiation were counted by flow cytometry, respectively. Through assessing the correlation among apoptosis and irradiation dose and culture time after irradiation, the optimal dose of irradiation and reference time of sampling were determined for the animal experiment next. 2. 21 BALE/c nude mice with orthotopic human gastric cancer were randomized into three groups, of which 7 mice were in A group (Comparative groupY. 7 in B group (group of 24 hour after irradiation) and 7 in C group (group of 48 hour after irradiation). The whole stomachs of nude mice including implanted tumor were irradiated with 6 MV X梤ays at 2OGy. The pathological changes of implanted SGC-79O1GCC and normal mice gastric mucosae were examined by light microscope (LM) and transmission electron microscope (TEM) after ionizing radiation. At the some time, using the methods of terimal deoxytransferase (TUNEL) and immunohistochemieal staining (ABC), the changes of apoptosis index and Fas expression were investigated in m these two different tissues, respectively. 3. Using the method of immunohistochemical staining (ABC), the changes of inducible nitric oxide synthase (iNOS) expression level in both the implanted SGC-9OIGCC and the normal mice gastric mucosae after irradiation were observed by computed imagine-analysis cytometry, respectively. Results: 1. In vitro, the apoptotic indexes of SGC? 79O1GCC began 40 increase 12 hour after irradiation, reached peak at 24 hour and decrease at 48 hour, The maximum of Al after irradiation with 5Gy.. 1OGy and 2OGy were 32.1%.. 35.7% and 49.3%, respectively, of which Al at 24 hour after irradiation of 2OGy was significantly different from that of 5Gy or lOGy. All AIs after ionizing radiation were significantly higher than that of non- irradiation groups. By means of the experimental results, the optimal dose of irradiation-enhanced apoptosis in SGC- 790 IGCC was 2OGy, and 24 hour and 48hour after irradiation were the time of sampling. 2.In vivo, the implanted tumor apoptosis indexes of A group.. B group and C group were 14.93%±4. 53% , 28. 54%± 4. 54% and 16. 30% ±4. 76%, respectively, and Fas labeling indexes were 15. 39%±4.43%., 30. 75%±5. 50% and 20. 06%±3.77%, respectively, of which both AT and Fas LI of B group were very significantly higher than that of A group (p<0.01). The changes between Al and Fas LI in these groups had similar tendency that showed a significant positive correlation. In terms of mice gastric mucosa cells, the apoptosis indexes of A group.. B group and C group were 46. 32%±6.62%.. 56. 72%±5.84% and 41.87%±7.97%, and Fas LI. were 47. 71%±9. 34%., 64. 34% ±9. 51% and 55. 85%±10. 38%, respectively. Except tha...
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