| ObjectiveThrough cytology experiment and animal experiment, this paper aims to investigate the influence of Iodine-125particle on apoptosis,proliferation and suppression of breast carcinoma cell when Iodine-125particle keep closely irradiating with low doses. At the same time, the paper probes the influence of Iodine-125particle on Vascular endothelial growth factor (VEGF),Basic Firoblast Growth Factor (bFGF) and the expression genic and protein. It also improves the molecular biological mechanisms of the iodine-125(125I) particle in therapy of breast cancer, and provides experimental base for clinical application of125I particle in the treatment of breast cancer.MethodsPart1:The irradiation model of125I particle in vitro is designed and made. MCF-7of human breast cancer cells which were in the logarithmic phase were cultured in Petri dishes whose diameter is35mm; with a total number of eighteen, they were randomly divided into2groups:experimental group and control group. According to the exposure time(24h,48h,72h), these two groups were divided into six sub-groups:C-24, C-48, C-72, T-24, T-48, T-72, and three in each sub-group. The experimental group cells received125T particle (0.6mCi, ImCi=3.7×107Bq) irradiation and the control group cells made no intervention. After cells were irradiated respectively for24h,48h and72h, they were cultured and collected to use in the cell proliferation experiment, in flow cytometric analysis of apoptosis and RT-PCR method to detect mRNA expression level of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF).Part2:Tumor-bearing nude mice were randomly divided into experiment group and control group, with20nude mice in each group. Control group was implanted with blank particle and no125I particle; while the experiment group was implanted with125I particle(0.6mCi, ImCi=3.7×107Bq). After implantation, the long diameter and short diameter of the tumor were measured every three days to calculate the tumor volume and to map out the tumor growth curve. Nude mice were killed after28days, and dissected their tumor tissue to weigh, calculate the average tumor inhibition rate and produce tumor tissue samples for routine pathological examination. The mRNA and protein expressions of VEGF and bFGF were measured through RT-PCR and immunohistochemistry.ResultsPart1:(1) The irradiation model of125I particle in vitro with simple operation and safety is well-distributed. It shortens the experiment time, and save the cost of experiment.(2) From the cell growth curve, we knew that the growth of cells in the experiment group is slower than that in the control group; the doubling time of the cell population of the experiment group was2.210±0.049and the control group was1.581±0.053. There was Statistically significant difference between the two groups(t=5.789, p<0.01).(3) using flow cytometry to detect apoptosis rate; the24h,48h,72h apoptosis rate of control group were (1.97±0.53)%,(2.11±0.61)%,(2.04±0.44)%and the experiment group were (6.88±1.56)%,(11.10±1.22)%,(18.85±1.47)%. Compared two groups of the same point in time, there was significant difference (p<0.05).(4) In RT-PCR detection:mRNA expression of tumor cells in terms of VEGF and bFGF in the experiment group decreased, and had statistically significant with the control group(F=152.108,p<0.01; F=130.428,p<0.01).Part2:(1) The growth curve of the tumor indicated that the tumor growth of tumor-bearing nude mice in the experiment group was slow down, and had the tendency to shrink; while the tumor of control group grew rapidly. The average inhibition rate was49.36%by measuring tumor weight.(2) Through TUNEL method to detect the in situ apoptosis, the experiment group and control group apoptosis index were29%and8%. There was statistically significant difference between the two groups(χ2=14.624, p<0.01).(3) Through Immunohistochemical staining detection, protein expression of VEGF and bFGF in tumor in the experiment group were declined; compared with the control group, the difference was statistically significant.(VEGF:χ2=43.248; bFGF:χ2=41.119, p<0.01)(4) Through RT-PCR detection, the expression of VEGF mRNA and bFGF mRNA in the experiment group were decreased; compared with the control group, the difference between them was statistically significant.(VEGF:t=39.589; bFGF: t=28.210, p<0.01)Conclusion(1) The irradiation model of125I particle in vitro is one of the best model of the experimental irradiation of cells in vitro.(2)125I seeds implantation with continuous and close irradiation at low-dose rate can directly kill MCF-7breast carcinoma cells, inhibit the proliferation of cells, and the inhibition increases with the extension of time.(3)125I particle promotes apoptosis of breast tumor cells.(4)125I particle inhibits the expression of VEGF and bFGF mRNA and protein in Breast cells, inhibits angiogenesis effect of synergy.
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