Askoxylakis Vasileios, Mier Walter, Zitzmann Sabine, Ehemann Volker, Zhang Jianbing, Krämer Susanne, Beck Carmen, Schwab Manfred, Eisenhut Michael, Haberkorn Uwe
Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center (DKFZ) and University of Heidelberg, Heidelberg, Germany.
J Nucl Med. 2006 Jun;47(6):981-8.
Drug-targeting strategies can increase the efficacy and reduce the side effects and toxicity of conventional chemotherapy or may lead to new radiolabeled molecules useful for diagnosis and therapy. To identify and characterize new carrier molecules, we evaluated a peptide that had been identified by phage display technology.
The peptide p160 (VPWMEPAYQRFL) was prepared by solid-phase peptide synthesis and radiolabeled with (125)I or (131)I. The radiolabeled peptide and derivatives of it were used to study binding and internalization in vitro and to assess their distribution in tumor-bearing mice.
Cell-binding assays on the human neuroblastoma cell line WAC 2 indicated the affinity and specificity of (125)I-labeled p160 toward neuroblastoma cells. Binding of the (125)I-labeled p160 was inhibited up to 95% by the unlabeled peptide. Furthermore, 50% of the total bound activity was internalized into the neuroblastoma cells. Biodistribution studies on nude mice showed a higher tracer accumulation in tumors than in most organs. Perfusion of the animals reduced uptake in all tissues, whereas tumor uptake remained constant. Fluorescence-activated cell-sorting studies with fluorescein isothiocyanate-labeled p160 demonstrated an increased fluorescence signal. Investigation of the binding properties of the fragments p160-8-1, p160-8-2, and p160-8-3 indicated that the sequence EPAYQR might be of significance for the binding of p160.
These data indicate that the p160 peptide is an attractive candidate for the development of a neuroblastoma-specific vector that can be used for drug targeting or radiopeptide-based diagnosis and therapy.
药物靶向策略可提高传统化疗的疗效，降低其副作用和毒性，或可能产生可用于诊断和治疗的新型放射性标记分子。为了鉴定和表征新的载体分子，我们评估了一种通过噬菌体展示技术鉴定的肽。
肽p160（VPWMEPAYQRFL）通过固相肽合成制备，并用（125）I或（131）I进行放射性标记。放射性标记的肽及其衍生物用于体外研究结合和内化，并评估它们在荷瘤小鼠体内的分布。
对人神经母细胞瘤细胞系WAC 2的细胞结合试验表明，（125）I标记的p160对神经母细胞瘤细胞具有亲和力和特异性。未标记的肽可将（125）I标记的p160的结合抑制高达95%。此外，总结合活性的50%内化到神经母细胞瘤细胞中。对裸鼠的生物分布研究表明，肿瘤中的示踪剂积累高于大多数器官。对动物进行灌注可降低所有组织的摄取，而肿瘤摄取保持不变。用异硫氰酸荧光素标记的p160进行的荧光激活细胞分选研究显示荧光信号增强。对片段p160-8-1、p160-8-2和p160-8-3的结合特性研究表明，序列EPAYQR可能对p160的结合具有重要意义。
这些数据表明，p160肽是开发神经母细胞瘤特异性载体的有吸引力的候选物，可用于药物靶向或基于放射性肽的诊断和治疗。
