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Objective To investigate the effect of continuous irradiation with 125I radioactive seeds in inhibiting HepG2 cell proliferation and possible mechanisms in inducing apoptosis. Methods Human hepatoma cell line HepG2 was selected as the research object and exposed to continuous irradiation with 125I radioactive seeds. The initial dose rate was 5.32 cGy/h, and HepG2 cells were exposed to a dose of 0, 2, or 4 Gy. A light microscope and Hoechst33258 staining were used to observe the morphological change of HepG2 cells, the colony-forming assay was used to calculate plating efficiency, the scratch test was used to evaluate the change in migration ability, flow cytometry was used to measure cell apoptosis, and Western Blot was used to measure the expression of apoptosis-related proteins. An analysis of variance was used for comparison between multiple groups, and the least significant difference method was used for further comparison between any two groups. Results After HepG2 cells were exposed to 125I radioactive seeds at a dose of 0 Gy, 2 Gy, or 4 Gy, the 4 Gy group showed a reduction in cell density and an increase in the number of spherical free dead cells, as was shown by the light microscope; Hoechst33258 staining showed that the 4 Gy group had typical features of apoptotic cells, such as karyopyknosis, fragmentation, and margination. The colony-forming assay showed that there were significant differences in plating efficiency between the control group, 2 Gy group, and 4 Gy group (120.00%±3.61%, 112.00%±2.00%, and 45.00%±3.61%, F=508.90, P＜0.001). The scratch test showed that there were significant differences in cell migration rate between the control group, 2 Gy group, and 4 Gy group (21.24%±4.36%, 19.93%±3.37%, and 11.42%±0.65%, F=8.29, P＜0.001). The results of flow cytometry for cell apoptosis showed that there were significant differences in cell apoptosis rate between the control group, 2 Gy group, and 4 Gy group (4.33%±0.67%, 6.90%±1.31%, and 17.03%±1.43%, F=110.01, P＜0.001). Western blot showed that 125I irradiation significantly inhibited the expression of tumor proliferation-related protein PCNA, apoptosis-related protein Survivin, and Bcl-2 and promoted the expression of pro-apoptotic proteins Bak and Bax. Conclusion 125I radioactive seeds inhibit the growth of HepG2 cells through promoting HepG2 cell apoptosis and inhibiting proliferation and migration. The possible mechanism may be related to the inhibition of the expression of apoptosis-related proteins. |
