β-榄香烯对人肺腺癌A549细胞株裸鼠移植瘤放疗增敏作用的研究

Study on radiosensitivity ofβ-elemene to human lung adenocarcinoma A549 cell line transplanted tumor in nude mice

目的建立人肺腺癌A549细胞株裸鼠移植瘤模型,用增敏剂量的β-榄香烯联合放疗对移植瘤进行干预,探讨放疗增敏机制是否与抑制葡萄糖转运蛋白1(GLUT-1)表达有关。方法采用细胞悬液接种法建立裸鼠移植瘤模型,将肿瘤体积达到75 mm^(3)左右的20只裸鼠随机分为空白对照组(NS组)、β-榄香烯单药组(ELE组)、β榄香烯联合放疗组(ELE+RAD组)和单纯放疗组(RAD组)。监测干预后各组裸鼠肿瘤体积的变化,获得各组裸鼠的肿瘤生长曲线。通过计算增敏系数,检测45 mg·kg^(-1)β-榄香烯是否发挥增敏作用,采用Real-Time PCR、Western blotting及免疫组化染色检测各组移植瘤中GLUT-1的表达水平。结果成功建立A549细胞株裸鼠移植瘤模型,依据各组移植瘤体积变化绘制生长曲线。测得增敏系数(EF)为2.44,提示β-榄香烯的剂量已达到增敏效果。与NS组相比,实验组移植瘤GLUT-1 mRNA及蛋白表达水平均显著降低(P<0.01);ELE组与RAD组GLUT1 mRNA及蛋白表达水平无显著差异(P>0.05);与ELE组、RAD组相比,ELE+RAD组GLUT-1 mRNA及蛋白表达水平均显著降低(P<0.01)。免疫组化结果显示,与NS组比较,实验组GLUT-1的表达均被显著抑制(P<0.05);其中ELE组和RAD组GLUT-1的表达抑制作用相对较弱,RAD组的抑制作用略强于ELE组,但两组差异无统计学意义(P>0.05);而ELE+RAD组GLUT-1的表达抑制作用较强(P<0.05)。结论增敏剂量的β-榄香烯与放疗联合应用可显著抑制裸鼠移植瘤中GLUT-1 mRNA及蛋白表达,明显增强放疗对肺癌裸鼠移植瘤的生长抑制效果,提示β-榄香烯可能通过抑制GLUT-1表达发挥放疗增敏作用。

Objective To investigate whether the mechanism of radiosensitization is related to the inhibition of GLUT-1 expression by interfering with the transplanted tumor of human lung adenocarcinoma A549 cell line in nude mice with radiotherapy and sensitized dose ofβ-elemene.Methods The nude mice transplanted tumor model was established by cell suspension inoculation method,and 20 nude mice with a tumor volume of 75 mm^(3) were randomly divided into the blank control group(NS group),theβ-elemene single drug group(ELE group),theβ-elemene combined with radiotherapy group(ELE+RAD group)and the simple radiotherapy group(RAD group).The changes of tumor volume of nude mice after intervention were monitored,and the tumor growth curve of each group of nude mice was obtained.By calculating the radiosensitivity enhancement factor,the sensitivity enhancement effect of selected 45 mg·kg^(-1)β-elemene was detected,and the expression level and experimental data of GLUT-1 were detected by real-time PCR,Western blotting and immunohistochemical staining.Results The transplanted tumor model of A549 cell line in nude mice was successfully established,and the growth curve was obtained according to the volume changes of each group.The value of radiosensitivity enhancement factor was 2.44,which suggested that the dose ofβ-elemene has achieved the effect of sensitization in this experiment.Compared with the NS group,the expression of GLUT-1 mRNA and protein decreased significantly in the experimental group(P<0.01).There was no significant difference in the expression of GLUT-1 mRNA and protein between ELE group and RAD group(P>0.05).However,compared with ELE group and RAD group,the expression levels of GLUT-1 mRNA and protein in ELE+RAD group were greatly decreased(P<0.01).Immunohistochemical results showed that the expression of GLUT-1 was significantly inhibited in the experimental group as compared with the NS group(P<0.05).The ELE group and RAD group had a relatively weak inhibitory effect on GLUT-1 expression.The inhibitory effect of RAD group was slightly stronger than that of ELE group,but there was no significant difference between the two groups(P>0.05).However,the ELE+RAD group had a strong inhibitory effect on the expression of GLUT-1,which was statistically significant as compared with the other groups(P<0.05).Conclusion The sensitized dose ofβ-elemene combined with radiotherapy significantly inhibited the mRNA and protein expression of GLUT-1 in the transplanted tumors,and enhanced the inhibitory effect of radiotherapy on the growth of lung cancer transplanted tumor,indicating thatβ-elemene may play a role in radiosensitization by inhibiting the expression of GLUT-1.