| Summary: | 碩士 === 國立陽明大學 === 醫學生物技術研究所 === 91 === According to clinic statistics, IR is a major therapeutic modality that is primarily effective in the treatment of 50 percentage to generate tumors .DNA cytotoxic mechanisms by irradiation have been known as free radical and damage DNA but others are not very clear.In these studies , we gave examined the effects of Co60 radiation on KHT sarcoma injected in the hind limb of C3H mice .Our evidence demonstrated that irradiation decreased the vessel density of tumor in C3H mice. On day 32 after tumor cells being injected ,the average vessel number of tumor in control mice was 17.5±3.97(N=3)with a 200X magnification viewing field .Whereas, 10GY radiation and 20GY could significantly lower the average vessel density to 10.65±2.44(N=3) and 5.45±1.89(N=3) respectively (n=3)(P < 0.05). The morphologic observations indicated that the death of tumor following radiation treatment can be caused by both necrosis and apoptosis. The degrees of necrosis and apoptosis caused by radiation was found to be a dose-dependent manner as well as vessel density decreasion. Irradiation also decreased the extent of lung metastases. On day 39 after tumor cells injection, the number lung colonies in control mice was 21.33±4.16(N=3) Whereas, 10GY radiation and 20GY treatment significantly lower the lung metastases to 13.67±1.53(N=3) and 2.66±2.05(N=3) respectively (N=3) .Irradiation was shown to lead to the production of tumor survival factors, including VEGF and bFGF. On day 4 after irradiation, the expression of VEGF and bFGF were higher than theat of control group and may induce antiapoptotic responses and, promote tumor growth after.Irradiation could actively exert proangiogenic expression by experimental tumors the VEGF and bFGF induction may represent a protective response to radiation stress by tumor cell.Taken together, radiation decreased the vessel density of tumor and lung metastasis; induced VEGF and bFGF expression and prolong the survival in tumor-bearing host.
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