Study On VEGF And Gax Expression In Human Breast Cancer Cell Line (MCF-7) Irradiate By Iodine-125

Objective:This study investigaged the effects of the iodine—125 on expression of the level of vascular endothelial growth factor and growth arrest-specific homeobox in human breast cancer and induced apoptosis,and the effective of iodine -125 seed in treating human breast cancer.Methods:The irradiator consisted of nine iodine-125 seeds,each with 0.8mCi of apparent activity.Eight seeds were equally spaced around the circumference of a 3-cm diameter circle and the ninth seed was confined to the center.Human breast cancer cells(MCF-7) were placed 5mm above the seed plane and delivered. Human breast cancer cell(MCF-7) is plant in the petri dish(diameter 35mm),when cells are be adherent,and be irradiated by iodine-125 seeds.The cells were divided into 2 groups(control group and experiment group),the control group for non—irradiated group,the experiment group for the irradiation group.The control group cells(no irradiation)were cultured 24 hours,48 hours and 72 hours respectively. The experiment group:the MCF-7 cells were irradiated by 24 hours,48 hours and 72 hours,and then we collected the specimens and frozen them,respectively.We detect cell apoptosis with flow cytometry and clairvoyant electron microscopy.We detect the mRNA expression levels of vascular endothelial growth factor(VEGF) and growth arrest-specific homeobox(Gax) at the different time—point by RT—PCR respectively.Results:Human breast cancer(MCF-7) cells were exposed by continuous low-dose irradiation of iodine-125 seeds.The rate of apoptosis was determined by flow cytometry.The results showed that the apoptosis rates of the control group cells were (2.19±0.70)%(n=6,time=24h),the apoptosis rates of the control group cells were (2.00±0.66)%(n=6,time=48h) and the control group cells were(1.94±0.40)%(n =6,time=72h).The apoptosis rates of the the experimen group cells were (6.76±1.24)%(n=6,time=24h),the apoptosis rates of the exporimen group cells were(10.90±1.16)%(n=6,time=48h) and the experimen group cells were (17.79±1.54)%(n=6,time=72h).The resultsof clairvoyant electron microscopy showed that the control group cells have no apoptosis,apoptosis can bc seen in experimental group significantly.Through semi-quantitative RT-PCR detection showed that VEGFmRNA expression of the experimen group ware decreased,while the GaxmRNA expression of the exporimen group ware increased.Conclusions:1.Iodine—125 seeds can promote apoptosis in human breast cancer cell line(MCF-7),and the cells apoptosis rates are higher with extended radiation time. 2.The molecular biology mechanism of iodine—125 seeds to inhibit MCF—7 cell is to decrease the VEGF expression and to increase the Gax expression inMCF-7 cell.