Preliminary Study On Radiation-sensitizing Effect And Mechanism Of Curcumin On Ectopic Transplanted Tumor Of Esophageal Carcinoma Eca-109 Cells In Nude Mice

Objective: The morbidity and mortality of esophageal neoplasms are among the top of the world,furthermore,there is a trend of increasing year by year.Owing to the difficulty of early diagnosis and high invasiveness degree,the prognosis of esophageal neoplasms is poor.Squamous cell carcinoma is a common pathological type of esophageal neoplasms in China.In the treatment of esophageal malignant tumor,radiotherapy is an effective local therapy to improve local control,as well as prolong patients survival time and improve living quality.However,despite the continuous development of radiotherapy technology,the efficacy of radiotherapy for esophageal neoplasms is still far from satisfactory.Therefore,it is crucial to search for an effective radiosensitizer to achieve better tumor inhibition at the same dose and reduce damage to the surrounding tissue.Curcumin is a kind of traditional Chinese medicine monomer extracted from Zingiberaceae and Araceae.It has been proved to enhance the effect of ionizing radiation in many kinds of tumors in vivo and in vitro.In this study,we established a model of ectopic transplantation of esophageal neoplasms cells Eca-109 in nude mice,observed the growth of tumor after intervention of curcumin and radiation,detected apoptosis and the expression of related proteins in tumor tissue,verified the sensitizing effect of curcumin in radiotherapy of esophageal neoplasms in vivo,and explored its sensitizing mechanism.Method: Human esophageal cancer Eca-109 cells were cultured,Eca-109 cells were subcutaneously transplanted into nude mice.When the maximum diameter of transplanted tumor reached to 6 ± 0.3mm,25 nude mice were randomly divided equally into 4groups.Each group were treated with: A(control group): normal saline was administered by gastric perfusion at the dose of 20ml/kg/d;B(curcumin group): curcumin solution was administered by gastric perfusion at the dose of 200mg/kg/d;C(radiotherapy group):normal saline was administered by gastric perfusion at the dose of 20ml/kg/d,and local single 6MV-X way irradiation of 4Gy was given to the subcutaneously transplanted tumor after 10 days;D(radiotherapy with curcumin group): curcumin solution was administered by gastric perfusion at the dose of 200mg/kg/d,and local single 6MV-X way irradiation of 4Gy was given to the subcutaneously transplanted tumor after 10 days.During the intervention,we gauged the body weight of nude mice and the diameter of transplanted tumor in each group,the average tumor volume and tumor inhibition rate of each intervention were calculated,then we charted the curve of tumor growth and the rate of tumor inhibition.The nude mice were sacrificed to strip the transplantation tissue 7 days after radiotherapy,and measured the volume and weight of tumor.Flow cytometry was used to detect rate of neoplasm cells’ apoptosis and mitochondrial membrane potential.Western blotting technique was used to analyze the expression of NF-kappa B,TNF and AKT protein.All the data measured above were statistically analyzed by Graphpad prism7.Result:1.After radiotherapy,the body weight of group C and D decreased,the curve of body weight showed that the body weight of group D was higher than group C.The average tumor volume and weight of each intervention group were lower than the control group.Despite that there was no significant difference between group A and group B in tumor volume(P>0.05),significant differences exists among other groups(P < 0.05).The rate of tumor inhibition in group B,C and D were 24.11%,45.48% and 67.12%.2.In each intervention groups,the apoptosis rate of was higher than the control group,and the apoptosis rate of group D was higher than group C,the difference was statistically significant(P < 0.05).There was no significant difference in mitochondrial membrane potential among the groups.3.The expression of NF-κB in group D was significantly lower than group C(P <0.05).However,there was no significant difference in the expression of TNF and Akt between group D and group C.Conclusion:Curcumin may inhibit the growth of esophageal cancer Eca-109 in subcutaneously transplanted tumor,and significantly improve the radiosensitivity of transplanted tumor.Curcumin could inhibit the expression of NF-κB,which may be the possible mechanism of sensitization effect,thus inhibiting the transcription of downstream genes,in addition to promoting the apoptosis of esophageal cancer Eca-109 transplanted tumor after radiotherapy.