新型多肽示踪剂131I-RRL肿瘤分子显像研究

研究能与肿瘤血管内皮细胞特异结合的小分子多肽显像剂精氨酸-精氨酸-亮氨酸（RRL）对黑色素瘤小鼠模型的肿瘤分子显像应用价值。采用氯胺-T法对小分子多肽RRL进行¹³¹I标记，并对标记条件进行了优化；最佳标记条件为：RRL用量50 μg，Na¹³¹I用量10 μL（74 MBq），氯胺-T用量90 μg，反应总体积100 μL，振荡反应 3 min。标记率＞69%。用Sephadex G25柱对标记产物进行纯化，纯化后放化纯度＞95%。采用绿色荧光素（FITC）标记RRL，并进行体外细胞结合实验，通过荧光信号的强弱观察RRL在不同细胞中的结合能力。体外细胞结合实验结果显示，RRL不仅能够特异性结合于肿瘤来源的血管内皮细胞，而且能够与肿瘤实质细胞结合；¹³¹I-RRL对黑色素瘤动物模型进行SPECT显像结果显示，¹³¹I-RRL能够特异性浓聚于肿瘤组织，24 h后放射性浓聚灶清晰可见。以上结果表明，小分子多肽RRL是一种很有潜力的肿瘤放射性核素分子显像与治疗的载体。

Study of Novel Peptide Probe ~(131)I-RRL for Tumor Molecular Imaging

To study the potential application value of Ary-Ary-Leu（RRL） specially combined with tumor derived endothelial cells in tumor molecular imaging for melanoma bearing mice,a novel peptide RRL was designed and labeled with 131I by chloramine-T method,and mice bearing melanoma tumor were injected 131I-RRL to imaging.The labeling results showed that the optimized condition were following： 50 μg RRL,10 μL（74 MBq）Na131I,90 μg chloramine-T,total reaction volume 100 μL,and reaction time 3 min,the labeling yield was over 69%.The labeling compound was purified by Sephadex G25,its radiochemical purity was 95%.In vitro binding experiments,FITC-RRL was mainly combine with tumor cells and tumor angiogenesis endothelial cells,and in the SPECT imaging,131I-RRL peptide could successfully image the tumor in nude mice bearing melanoma tumor for 24 h after injection.The results indicated that small molecular peptide RRL was a promising carrier for tumor molecular imaging and radioimmunotherapy.