Purpose: To detect the expression of p65, a subunit of NF-κB proteins, and apoptosis after adenoid cystic carcinoma cells(ACC-2) irradiated by high energy X-ray, and to investigate the interaction between them.
Methods: ACC-2 cells were cultured and then irradiated by high energy X-ray of different dose(2, 4, 6, 8,10Gy). At the next six time points(1, 3, 6, 10, 24, 48h), the expression of p65 protein in cytoplasm and nucleus was detected by immunocytochemistry and Western blotting. The apoptotic cells were counted by flow cytometry and then observed by TUNEL technique. The data of radiant intensity and apoptotic rate were statistically analyzed by Spearman method with SPSS11.5 software package.
Results: In ordinary condition, p65 protein seldom appeared in the nucleus, and mostly stained in the cytoplasm by immunocytochemistry. After irradiation, the protein was observed around the nuclear. Then it went through the nuclear membrane more and more as time going on, finally to the center of the nucleus. The quantity of p65 among the total protein changed gradually after radiation, rising at first, which got to a peak after about 6 to 10 hours, according to the results of Western blotting. At the same time point, p65 protein was found to have a higher expression with a higher dose of irradiation correspondingly. The proportion of apoptotic cells also varied from time to time, and an obvious valley of the apoptotic curve was at the 10th hour after radiation. Compared with the outcome of Western blotting, the results indicated a negative correlation between the apoptotic rate and the radiant intensity or p65 protein expression(P<0.05).
Conclusions: The expression of p65 protein is affected by the irradiation of p65 of high energy X-ray, which is dose-time dependent. The proportion of apoptotic cells decreases as the expression increases.