Killing Effects Of Steep Pulsed Electrics Fields On Lymphatic Capillaries VX₂ Implanted Breast Tumor Of Rabbits

Objective: Lymphatic metastasis is the capital pathway of metastasis of tumor and the cause of unfavourable prognosis of patients .The regional lymphocapillary vessels pay a vital role in the lymphatic metastasis.VEGF-C/ VEGFR-3 (FLT-4) signalling which is mediated of lymphogenesis or dilation of lymphatics is closely correlated with lymphogenesis of tumor.The study is aim to investigate the killing effects of steep plused electrics fields(SPEFs) on lymphatic capillaries and the expressed contribution of VEGF-C, FLT-4 in VX2 implanted breast cancer of rabbits ;To explore other mechanisms of SPEFs. Materials and Methods: 25 rabbits which were successfully established breast cancer model were randomly devided into control and experiment group .A certain dosage of SPEFs was exerted to the experimented group,then adopt isosulfan blue dye injection staining and 5'-AMP-ALPase enzymohistochemical double staining, and electron microscopy to examine the morphological change of lymphatic capilliaries.SP immunohistochemical stain was used to detect the tumor expression of VEGF-C,FLT-4 in breast cancer .The positive rate was qualitatively assessed in both groups, and the number of immunostained positive tumor cells was counted in a microscopic grid. Statistical significance of the data obtained was analyzed by the Student t test. Results:1.the morphological change of lymphatic capillaries: Compared to control group,after isosulfan blue dye injection no annular lymphatic vessels stained with isosulfan blue were found under microscopic examination;enzymohistochemical staining showed that there was no positive staining in the Steep Pulse-treated region ,and the integrity and succession of lymphatics were destroyed by examine of transmission electron microscope.2. The expression of VEGF-C,VEGFR-3:The positive rate of tumor-origin VEGF-C, FLT-4 was 96.67%, 90.00% respectively;while in experiment group the positive rate was56.67%, 43.33% respectively. The positivities of these two factors were lower in SPEFs group than those in control group, and there were significant differences of VEGF-C, FLT-4, between two groups (P<0.05). The number of positive tumor cells of VEGF-C in breast cancer was 344.5±90.6/mm2 in control group ;while in SPEFs group the number was 235.9±93.8/mm2 .The cell of expressions of VEGF-C were significantly lower in SPEFs group than those in control group (P<0.05). Conclusions: 1,SPEFs could induce severe destruction of lymphatic capillaries and vessels of VX2 implanted breast cancer. Therefore, it may decrease the possibility of lymphatic metastasis after Steep Pulse treatment of breast cancer .2, The function and turnover of destructive lymphatics to wait for further study.3,the SPEFs inhibited the expression of VEGF-C and FLT-4,and also interfere the metastasis of tumor indirectly.