| Objective:To observe and explore the antitumor effect and the antimetastatic effect of halofuginone when combined with radiation. Try to explore the mechanismas.Methods:The toxicity of halofuginone was observed with the dose of 10μg/day, 25μg/day and 50μg/day, and the appropriate dose of halofuginone was determined before experiments started. Lewis lung cancer cells were cultured and inoculated intradermally into the C57BL/6J mice to establish xenograft models to observe the the antitumor effects of halogufinone. Thirty-seven C57BL/6J mice were randomly divided into 4 groups:7 in control group, without any treatment; 10 in halofuginone group, with halofuginone gavage administration of 25μg daily for each mouse for 10 days; 10 in irradiation group, X-ray irradiaton with 3Gy/fx10f; 10 in combination group, with halofuginone gavage administration as in halofuginone group 1 hours before irradiation, and irradiation was given as in the irradiation group. The tumor diameter was measured with the vernier caliper and the body weight of mice was measured with the balance every other day. Three days after the experiment,4 mice were killed randomly in each group(3 in control group), mice tumors were weighed and photographed. Each tumor was cut into two parts, one for immunohistochemistry to detect TGF-β1, MVD and type I collagen level, and the other for ELISA to detect TGF-β1. The survival time were observed in the remaining mice. All mice were killed on day 90 to observe the hepar and pulmonary metastasis.Results:Halofuginone with 10μg/day,25μg/day had no effect on mouse physiology after 3 weeks of administration, but one mouse died in the 50μg/day group, other mice were unresponsive. Drug concentration used in this experiment was 25μg/day. There's no statistical difference in tumor volume among the different groups before treatment. After 5 days of treatment, tumors in the halofuginone group (P=0.023), irradiation group (P=0.002) and combination group (P=0.000) were significantly smaller than in the control group and the tumor volume in the combination group was smaller than in the halofuginone group (P=0.049). After 9 days of treatment, tumor volume in the halofuginone group (P= 0.000), irradiation group (P=0.000) and combination group (P=0.000) were significantly smaller than in the control group, and it was significantly smaller in the combination group than in the halofuginone group (P=0.002) and irradiation group (P=0.038). This phenomenon was more and more obvious as the observation time lasted. Body weight of mice in each group had no statistical difference before treatment. As treatment processed, body weight was highter in the halofuginone group, irradiation group and combination group than in the control group, but there was no significant difference. The average tumor weight in the halofuginone group (P=0.000), irradiation group (P=0.000) and combination group (P=0.000) was significantly lower than in the control group, and it was significantly lower in the combination group than in the halofuginone group (P=0.015) and irradiation group (P=0.044). The survival time were statistically longer in halofuginone group (P=0.032), irradiation group (P=0.005) and combination group (P=0.001) than in the control group. The longest survive time was observed in the combined group, but with no significant difference than in the halofuginone group and irradiation group. Liver and lung metastases in the control group were most and combination group were least. Immunohistochemical results:TGF-β1 level in the tumor tissue in the halofuginone group (P=0.003) and combination group (P=0.035) were significantly lower than in the control group, and it was higher in the irradiation group than in the control group (P=0.047). MVD in combination group was lower than in the control group (P=0.000), halofuginone group (P=0.023) and radiotherapy group (P=0.000), MVD was lower in the halofuginone group than in the control group (P=0.000). The type I collagen expression in tumor tissue was higher in the control group and radiotherapy group than in the halofuginone group and combination group. ELISA results:Tumor tissue TGF-β1 level in the halofuginone group (P=0.000) and combination group (P=0.000) was significantly lower than in the control group and irradiation group.Conclusion:Halofuginone has significant radiation sensitizing effect. Haloguginone combined with radiation therapy can not only suppress tumor growth in situ but also inhibit the liver and lung metastasis. Halofuginone combined with radiotherapy can promote tumor necrosis, inhibit tumor angiogenesis and inhibit type I collagen expression in tumor tissues. Halofuginone significantly inhibited the expression of TGF-β1, and can reduce the trend of TGF-β1 increase after radiation therapy. Halofuginone is expected to be a new promising radiation sensitizer. |
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