| Radiation therapy is one of the basic and important treatment to cancer, studies have shown that in all cured cancer patients, radiotherapy and combined treatment with radiotherapy methods contributed mainly up to 40%.Although the radiation therapy equipment and technology have been a breakthrough,the results have still not good.Application of radiosensitizer can increase the sensitivity of tumor cells to radiotherapy, improve the tumor cell-killing rate,enhance radiotherapy,and have no or very little toxicity to normal tissue.β-elemene,an active ingredients, extracted from Chinese medicine curcuma.At present, results suggested that elemene has a significant direct cytotoxic effect to various of tumor cells,which can induce cell apoptosis and differentiation,reverse the multidrug resistance,anti-tumor cell invasion migration and metastasis,moreover,it can improve immunity and has low toxic effects etc.In addition,β-elemene has aradiation sensitizing effect.The study of the sensitization mechanism of elemene is mainly about the apoptosis,cell proliferation and the immunogenicity,but few about tumor blood vessel.Objective:Established the human lung adenocarcinoma A549 cell line nude model.Observated the effect of theβ-elemene on tumor growth inhibition.At last,explored the mechanism of elemene sensitivity whether there is relationship between the sensitization mechanism of elemene and the VEGF,survivin expression.Methods:Our take the human lung adenocarcinoma A549 cell line xenograft nude mouse model as the object in our study.The cells cultured in RPMI-1640,and the nude mice were kept in SPF conditions.Our study establishes engraft models through the cell suspension inoculation. After the model successfully established,the radiotherapy group and the combined treatment group were treated the 6MeV electron linear accelerator irradiation.At last,detected the expression of VEGF and survivin by immunohistochemistry.Results:1. After vaccinated, there were skin redness in nude mice body, no tumor growing in 6-9 days.At first the tumor is oval-shaped, smooth,and then slowly the tumor was becoming irregular shape and nodular surface. After treatment, the control group and the drug of 25mg/kg group mice's eating and activity decreased obviously and tumor growth faster,while the radiotherapy group and combined group has nothing in eating and activity, the tumor growth slower than the former two group.The drug of 45mg/kg group mice's eating and activity was better than the.drug of 25mg/kg group mice's,and worse than other groups.2. Tumor formation rate.The female had 87.1%tumor formation,while the male was13.3% at the same time,compared to the female nude,male nude mice occurred earlier and faster rate of cachexia,while Immature male nude mice tumors were different degrees of cachexia death.3. Sensitivity coefficient.The EF values of P-elemene concentration of 25mg/kg,45mg/kg,100mg/kg was 0.908,1.5,2.625,which suggested that there exists significant differences in sensitivity.4. Inhibition rate.Nude mice were griver intraperitoneal injection of elemene concentration of 25mg/kg,45mg/kg,100mg/kg,48h after the measurement of the volume of solid tumors,the inhibitory rate=(l-experimental group's tumor volume/control group's tumor volume)×100%, the tumor inhibition rate was 1.41%,17.30%,40.85%.5. Morphological characteristics of each group A549 tumor.The tumor was confirmed by the A549 lung adenocarcinoma engrafts, ancer tissue and cell can be seen under the light microscope,which had round or oval cells, large nuclear, cytoplasm was little transparent,different size of cells,also we can see the cancer nests,duct and gland cavity.By HE staining, observated the pathological changes of each groups under the light microscope,the result revealed that necrosis is not obvious in control,drug group and radioation group had lots of necrosis,while combination group had the most necrosis tissue and cell.(Shown in photo B1-4)6. The expression of VEGF and survivin.Tested the expression of VEGF and survivin by immunohistchemistry.The results suggested that VEGF and survivin staining under the microscope was brown or tan were positive,located in the cytoplasm or nucleus.Semi-quantitative immuno-histochemical analysis showed the expression of VEGF and survivin combitated group was lower than any groups(p<0.05),while radiation group had better expression than control group(p<0.05), expression.According to the statistical analysis, survivin and VEGF in the combination group had statistical significance compared with other groups; radiotherapy group was significantly increased compared with control group(p<0.05).Conclusion:1.The method of direct subcutaneous injection of cell suspension had successfully established A549 lung adenocarcinoma nude mice model.2.β-elemene had a direct anti-tumor effect to lung adenocarcinoma A549, and had a dose-dependent effect;45mg/kg P-elemene group had a lower anti-tumor effect,but it can sensitize effect of radiation therapy, the rate was 1:5.3. At the concentration of 45mg/kgβ-elemene and radiation, which group can reduce the expression of survivin this effect suggested theβ-elemene can reduce tumor apoptosis may be related to the Inhibition of survivin expression.4. the concentration group of 45mg/kgβ-elemene and radiation reduced the expression of VEGF,which suggestedβ-elemene's sensitization mechanism may be related to the inhibition of tumor blood vessel formation, which suggested thatβ-elemene may improve the hypoxia of the tumor tissue to increase effect of the Radiosensitizer.That may be need further research.
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