An experimental study on irradiation-induced iNOS expression and apoptosis in orthotopic human gastric carcinoma cells and mice gastric mucosa cells

Objective: To provide evidence to the hypothesis of irradiation-induced apoptosis dependent on the induction of iNOS after irradiation. Methods: Twenty one model mice were randomized into three groups, of which 7 mice were in A group (comparative group), 7 in B group (group of 24 hour after irradiation) and 7 in C group (group of 48 hour after irradiation). By TUNEL and ABC, the changes of apoptosis and iNOS expression were investigated in two different tissues, respectively. Results: The implanted tumor AI in A group, B group and C group were (14.93 ± 4.53)%, (28.54±4.54)% and (16.30±4.76)% respectively, of which AI in B group was very significantly higher than that in the A group (P<0.01). The changes between AI and iNOS expression showed a significant positive correlation. To mice gastric mucosa cells, iNOS expression level in B or C group was very significantly higher than that in A group (P<0.01). But AI among all groups was not statistical significance. Conclusion: (1) Ionizing radiation can induce apoptosis in SGC-7901 GCC and up-regulate iNOS expression. (2) Up-regulated iNOS expression maybe participate in the apoptotic process of implanted tumor. (3) Ionizing radiation can not induce apoptosis in the mice gastric mucosa cells, but can up-regulate iNOS expression