放射性125I粒子植入对人肺腺癌裸鼠移植瘤微血管生成的影响

Effect of 125I seed implantation on the angiogenesis of transplanted human lung adenocarcinoma in nude mice

目的 探讨放射性125I粒子植入对人肺腺癌裸鼠移植瘤微血管生成的影响及其作用机制。方法 制备人肺腺癌细胞A549裸鼠皮下移植瘤模型24只，采用随机数字表法分为4组，每组6只，0、22.2、29.6 MBq组和对照组。用18 G植入针在各组裸鼠瘤体内分别植入放射活度为0、22.2和29.6 MBq 125I粒子，每个移植瘤内植入一枚，对照组不予处理。观察肿瘤生长情况，每4天测量肿瘤大小。30 d后处死裸鼠，绘制肿瘤生长曲线。瘤组织免疫组织化学S-P法检测微血管密度（microvascular density，MVD），并分别用RT-PCR、Western blot法检测血管内皮生长因子（vascular endothelial growth factor，VEGF）和缺氧诱导因子-1α（hypoxia inducible factor-1α，HIF-1α）的mRNA及蛋白的表达。结果 粒子植入治疗后54 d，22.2、29.6 MBq组移植瘤体积明显小于对照组（q=14.117、17.075，P〈0.05），但0 MBq组与对照组、22.2与29.6 MBq组瘤体积差异均无统计学意义（P〉0.05）。CD34阳性染色结果显示，22.2 MBq组的MVD为522±119，29.6 MBq组为491±121，明显低于对照组的922±260（q=4.826、5.197，P〈0.05），但0 MBq组与对照组、22.2 MBq组与29.6 MBq组差异均无统计学意义（P〉0.05）。RT-PCR检测表明，22.2 MBq组的VEGF和HIF-1α mRNA相对表达量分别为0.279±0.0659和0.370±0.0857，29.6 MBq组为0.215±0.0620、0.278±0.0651，均低于对照组（q=18.881、17.211和15.376、14.733，P〈0.05），但0 MBq组与对照组、22.2 MBq组与29.6 MBq组之间差异均无统计学意义（P〉0.05）。Western blot结果显示，22.2 MBq组与29.6 MBq组瘤组织VEGF和HIF-1α蛋白表达均明显减少，与对照组相比，差异有统计学意义（q=5.848、6.263和6.560、7.576，P〈0.05），但0 MBq组与对照组以及22.2 MBq组与29.6 MBq组差异均无统计学意义（P〉0.05）。结论 放射性125I粒子植入能有效抑制人肺腺癌裸鼠移植瘤微血管生成。

Objective To investigate the effect and underlying mechanism of radioactive 125I seed implantation on the angiogenesis of transplanted human lung adenocarcinoma in nude mice.Methods An animal model of transplanted human lung adenocarcinoma was established by subcutaneous implanting A549 cells into nude mice. Twenty four tumor-bearing nude mice were randomly divided into 4 groups with different irradiation doses of blank control （without any treatment） and 0 MBq, 22.2 MBq, 29.6 MBq and by embedding radioactive 125I seeds with an 18 G implant needle. Tumor volumes were measured every 4 days until all mice were terminated 30 d later and the tumor growth curve was drawn. The microvessel density （MVD） in the tumor tissue was detected by immunohistochemistry S-P assay. The mRNA and protein levels of VEGF and HIF-1α of each group were detected by RT-PCR and Western blot, respectively. Results After embedding of 125I seeds, the tumor volumes of 22.2 MBq group （886±97） and 29.6 MBq group （590±107） were significantly smaller than those of control group （2 297±149） at 54 d after administration （q=14.117, 17.075, P〈0.05）, but there were no significant differences among 0 MBq group and control group, 22.2 MBq and 29.6 MBq groups（P〉0.05）. The immunohistochemical CD34-positive staining demonstrated that MVD in 22.2 MBq group （522±119） and 29.6 MBq group （491±121） were decreased significantly compared with control group （922±260） （q=4.826, 5.197, P〈0.05）, but there were no significant differences among 0 MBq and control groups, 22.2 MBq and 29.6 MBq groups（P〉0.05）.The mRNA expressions of VEGF and HIF-1α in 22.2 MBq group （0.279±0.0659, 0.370±0.0857） and 29.6 MBq group （0.215±0.0620, 0.278±0.0651） were significantly lower than those in the control group （qVEGF mRNA=18.881, 17.211,qHIF-1α mRNA=15.376, 14.733, P〈0.05）, but there were no significant differences among 0 MBq and control groups, 22.2 MBq and 29.6 MBq groups（P〉0.05）. At the same time, the expression levels of VEGF and HIF-1α protein after 125I seed implantation were also obviously decreased in 22.2 MBq and 29.6 MBq groups （qVEGF=5.848, 6.263, qHIF-1α=6.560, 7.576, P〈0.05）, and no significant difference between 0 MBq and control groups（P〉0.05） and between 22.2 MBq and 29.6 MBq groups（P〉0.05）. Conclusions Interstitial implantation with 125I seeds may potently inhibit angiogenesis in human lung adenocarcinoma xenografts of nude mice.