The Studies Of The Radiobiogical Effects On Breast Cancer Between Hypofractionated Irradiation And Conventional Irradiation

Objective1.To observe the effects of different doses of radiation on the radiobiological effects of triple-negative breast cancer cells and the effects on the proliferation of transplanted tumors in triple-negative breast cancer mice.2.To investigate the effects of hypofractionated irradiation and conventional irradiation on systemic immune function in mice with transplanted breast cancer.Materials and Methods1.In this study,three-negative breast cancer cell MDA-MB-231 was radiated by 0Gy,2Gy,4Gy,8Gy,10 Gy.The effects of different doses on the cell cycle and apoptosis of MDAMB-231 cells were detected by flow cytometry.The inhibitory effect of different doses on the proliferation of breast cancer cells was detected by clone assay.Animal experiment was performed on nude mice bearing MDA-MB-231 transplanted tumor.The MDA-MB-231 transplanted tumors were irradiated in different fractionated radiotherapy,and the differences in tumor growth curves were compared.The difference of Ki-67 expression was detected by immunohistochemistry at 7 days and 14 days after irradiation.The difference of proliferation activity of transplanted tumor was monitored by Siemens Inveon PET / CT at 7 days and 14 days after radiotherapy.2.The 4T1 transplanted tumors were treated with 20 Gy,2Gy and 0Gy irradiation respectively.Using the caliper to record the length of the transplanted tumor,the growth curve was drawn.The tumor-bearing mice in the experimental groups were sacrificed at 4 days and10 days after irradiation.The percentage of CD4 +,CD8 + T cells in the tumors and blood were detected by flow cytometry.Resμlts1.With the increasing of irradiation dose,the cell cycle G2 / M phase arrest and apoptosis ratio of the three-negative breast cancer MDA-MB-231 cells was more obvious.The inhibition of proliferation activity was gradually enhanced with the increasing of irradiation dose.In the animal experiment,under different fractionated irradiation with the same dose,compared to conventional irradiation,the high single-dose irradiation in the inhibition of cell proliferation activity was stronger.What’s more,the level of Ki-67 expression and metabolic activities in tumor cells were lower with high single-dose irradiation.2.In the mice bearing-4T1 breast malignant tumor,Large dose of 20 Gy for tumor growth inhibition was significantly better than conventional dose 2Gy.The ratio of CD4 + T cells and CD8 + T cells in the 20 Gy group increased at 4 and 10 days after radiation,but the differences between the 2Gy group and the control group was not obvious.The percentage of CD8 + T cells in the irradiated group was lower than that in the untreated group,but the percentage of CD4 + T cells was higher than that of the untreated group.At 10 days after radiotherapy,There was no significant difference in the ratio of CD4 + and CD8 + T cells between irradiated group and non-irradiated group in the blood.Conclusion1.With the increase of dose,the effect of radiation on breast cancer MDA-MB-231 was enhanced,and when the dose reached 4Gy and above,it was possible that radiation coμld have better effect in killing MDA-MB-231 cells.Compared to conventional irradiation,The high single-dose radiotherapy had better effect in vivo inhibition of tumor cell proliferation.2.In the early stage of high dose irradiation,the proportion of CD4 + and CD8 + T cells in the tumor area decreased due to the recent killing effect.After 10 days of irradiation,there was an obvious anti-tumor immune response caused by high dose irradiation.But conventional irradiation might be weak in producing anti-tumor immunity.