Sensitization effect of endostatin for 125Ⅰ brachytherapy on transplanted tumor in nude mice

目的 探讨重组人血管内皮抑制素对125Ⅰ粒子植入治疗裸鼠肺癌移植瘤模型的辐射增敏效应.方法 建立裸鼠移植瘤模型,随机分成对照组(A组)、125Ⅰ植入组(B组)、重组人血管内皮抑制素组(C组)和125Ⅰ植入联合重组人血管内皮抑制素组(D组),每组20只.移植瘤直径达2 cm时行125Ⅰ粒子植入,处方剂量20 Gy,采用治疗计划系统计算移植瘤的体积及接受剂量.按每只裸鼠每天给予20 mg/kg重组人血管内皮抑制素,连续给药14d,观察并记录肿瘤生长的速度和瘤体体积的变化,分别于第1 5、30天时处死裸鼠,并通过免疫组化方法检测血管内皮生长因子(VEGF)的表达和微血管密度(MVD),通过RT-PCR分别检测各组肿瘤组织中αvβ3 mRNA水平.结果 第15、30天时,D组的重量抑瘤率和体积抑瘤率与B、C组相比明显增加,差异有统计学意义,B组和D组第30天时的重量抑瘤率和体积抑瘤率均较第15天时明显增加,差异有统计学意义.免疫组化结果显示,第15、30天时,D组与A、B、C组VEGF、MVD差异均有统计学意义,其中,C组与A、B组VEGF、MVD差异有统计学意义,C组第30天时的VEGF表达水平和MVD较第15天时增加,差异有统计学意义.RT-PCR结果显示,第15、30天时,与A组相比,B组αvβ3 mRNA的表达有所增加,并随时间的延长增加更明显,差异有统计学意义,而C组和D组αvβ3 mRNA的表达下降,差异有统计学意义.结论 重组人血管内皮抑制素对肺癌移植瘤的近距离辐射增敏作用明确,VEGF、MVD、αvβ3 mRNA的表达变化是其重要机制.Objective To investigate the radiation sensitization effect of endostatin on transplanted tumors in nude mice with 125Ⅰ radioactive seed.Methods Mice were randomly assigned to four groups (n=20):control group(group A),125Ⅰ radioactive seed group (group B),endostatin group (group C),and 125Ⅰ radioactive seed combined with endostatin group (group D).When the diameter of the transplanted tumor was greater than 2 cm,125Ⅰ radioactive particles were implanted.The prescription dose was 20 Gy.Treatment planning system was used to calculate the target area and size of tumors.Endostatin was injected intraperitoneally at 20 mg/kg once every day for 14 days,and the changes in tumor growth and size were observed.The animals were sacrificed at 15 and 30 days.The expression levels of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in tumor tissues were detected by immunohistochemistry,whereas αvβ3 mRNA levels were determined by RT-PCR.Results Compared with groups B and C,the tumor size,tumor weight,and tumor growth inhibitory rate of group D significantly increased at 15 and 30 days.The tumor size,tumor weight,and tumor growth inhibitory rate of groups B and D significantly increased at 30 days compared with those at 15 days.Immunohistochemical staining revealed that the expression levels of VEGF and MVD in group D were significantly different at 15 and 30 days compared with those in groups A,B,and C.The expression of VEGF and MVD in group C was significantly different at 15 and 30 days compared with that in groups A and B.VEGF and MVD in group C were significantly up-regulated at 30 days compared with those at 15 days.RT-PCR analysis demonstrated that the expression of αvβ3 mRNA in group B obviously increased with time compared with that in group A.Compared with group A,αvβ3 mRNA in group B was up-regulated,whereas αvβ3 mRNA in groups C and D was significantly down-regulated.Compared with groups C and B,group D exhibited a statistically significant difference.Conclusion Endostatin is helpful to brachytherapy of lung tumor with radiosensitizing enhancement effects.Changes in VEGF,MVD,and αvβ3 mRNA may be the rational treatment mechanism.天津市自然科学基金; 天津医科大学科学基金; National Natural Science Foundation of Tianjin; Science Foundation of Tianjin Medical University5357-3624