131I标记多肽K237用于前列腺癌荷瘤裸鼠显像的实验研究

目的研究将放射性核素131I标记多肽K237用于前列腺癌荷瘤裸鼠显像的可行性。方法按Iodogen法用131I标记多肽K237,用薄层层析法(TLC)测定标记率及放射化学纯度,经Sephadex G25柱凝胶过滤法分离纯化,获得标记率大于95%的131I-K237注射液。体外培养前列腺癌LNCap细胞株,构建LNCap荷瘤裸鼠动物模型,经尾静脉注射131I-K237,于特定时间处死、取肿瘤及主要脏器,测定各组织的放射性百分注射剂量率,研究荷瘤裸鼠体内131I-K237的生物分布。对荷瘤裸鼠尾静脉注射5.55Mbq131I-K237 1、2、4和8h后,分别用SPECT/CT仪显像,考察最佳显像时间。结果131I标记多肽K237的标记率为(73.7±3.2)%,经Sephadex G25柱分离纯化后,放射化学纯度为(96.7±0.6)%;LNCap前列腺癌荷瘤裸鼠体内131I-K237分布显示:30min和1、2、4、8、12、24h的T/NT比值分别是2.08和2.28、2.45、2.68、3.04、3.97、4.41。荷瘤裸鼠显像结果表明,1h时即可见肿瘤隐约显影,4h肿瘤显影最清晰。结论131I-K237的制备与显像操作简易,用于前列腺癌荷瘤裸鼠显像效果理想,有望成为一种新的针对前列腺癌的肿瘤显像剂。

Experimental Study on the Peptides K237 Radiolabeled with Iodine-131 for Targeting Imaging in Nude Mice Bearing Human Prostate Cancer

Objective To investigate the possibility of using the radionuclide131I label the peptide K237 and to explore the effects of the131I-K237 on the imaging and targeting therapy in nude mice bearing human prostate cancer.Methods Iodogen method was used to label the peptide K237.And the labeling efficiency and radiochemical purity were measured by the TLC method to get the131I-K237 injection whose labeling efficiency was greater than 95%.The human prostate cancer cell lines LNCap were cultured and the nude mice bearing human prostate cancer were built to study the biodistribution,imaging and the therapy of the131I-K237 in the animal model.The mouse were executed at the particular time after the tail vein injection of131I-K237.The percentage activity of injection dose per gram of the tumor and other organs were measured.The optimal time for imaging was investigated by comparing the131I-K237 SPECT for the nude mouse models bearing prostate cancer xenografts at different time points.Devided the nude mouse into three groups randomly including the physiological saline,K237 and131I-K237.The effect of the131I-K237 on prostate cancer was verified by the measure of the tumor volume and the imaging of the tumor at particular time.Results The labeling efficiency and radiochemical purity of131I-K237 were(73.7 ± 3.2) % and(96.7 ± 0.6) %,respectively.The T / NT ratios increased with time and were 2.08,2.28,2.45,2.68,3.04,3.97 and 4.41 at 30min,1,2,4,8,12 and 24h,respectively.The average tumor volume in group131I-K237,K237 and physiological saline were 0.61,1.03,1.82cm3.The average tumor volume of the mouse in groups131I-K237 were significantly smaller than that in others.The inhibition rate of the group131I-K237 and K237 was 69.01% and 45.91%.The SPECT imaging showed that the volume and the uptake of the131I-K237 in group131I-K237 was smaller.Conclusion131I-K237 can be prepared readily so that it may become a potential tracer for the prostate cancer.131I-K237 has a significant effect on the therapy of the nude mice bearing human prostate cancer.