一种用于前列腺肿瘤 PET 成像的异二聚体 [RGD-Glu-[(64)Cu-NO2A]-6-Ahx-RM2]αvβ3/GRPr 靶向拮抗剂放射性示踪剂。
A heterodimeric [RGD-Glu-[(64)Cu-NO2A]-6-Ahx-RM2] αvβ3/GRPr-targeting antagonist radiotracer for PET imaging of prostate tumors.
机构信息
Research Division, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO 65201, USA; Department of Radiology, University of Missouri School of Medicine, Columbia, MO 65211, USA; Department of Nuclear Applications, Ege University, 35100, Bornova, Izmir, Turkey.
Research Division, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO 65201, USA; Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
出版信息
Nucl Med Biol. 2014 Feb;41(2):133-9. doi: 10.1016/j.nucmedbio.2013.11.006. Epub 2013 Nov 28.
INTRODUCTION
In the present study, we describe a (64)Cu-radiolabeled heterodimeric peptide conjugate for dual αvβ3/GRPr (αvβ3 integrin/gastrin releasing peptide receptor) targeting of the form [RGD-Glu-[(64)Cu-NO2A]-6-Ahx-RM2] (RGD: the amino acid sequence [Arg-Gly-Asp], a nonregulatory peptide used for αvβ3 integrin receptor targeting; Glu: glutamic acid; NO2A: 1,4,7-triazacyclononane-1,4-diacetic acid; 6-Ahx: 6-amino hexanoic acid; and RM2: (D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2), an antagonist analogue of bombesin (BBN) peptide used for GRPr targeting).
METHODS
RGD-Glu-6Ahx-RM2] was conjugated to a NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid) complexing agent to produce [RGD-Glu-[NO2A]-6-Ahx-RM2], which was purified by reversed-phase high-performance liquid chromatography (RP-HPLC) and characterized by electrospray ionization-mass spectrometry (ESI-MS). Radiolabeling of the conjugate with (64)Cu produced [RGD-Glu-[(64)Cu-NO2A]-6-Ahx-RM2 in high radiochemical yield (≥95%). In vivo behavior of the radiolabeled peptide conjugate was investigated in normal CF-1 mice and in the PC-3 human prostate cancer experimental model.
RESULTS
A competitive displacement receptor binding assay in human prostate PC-3 cells using (125)I-[Tyr(4)]BBN as the radioligand showed high binding affinity of [RGD-Glu-[(nat)Cu-NO2A]-6-Ahx-RM2] conjugate for the GRPr (3.09±0.34 nM). A similar assay in human, glioblastoma U87-MG cells using (125)I-Echistatin as the radioligand indicated a moderate receptor-binding affinity for the αvβ3 integrin (518±37.5 nM). In vivo studies of [RGD-Glu-[(64)Cu-NO2A]-6-Ahx-RM2] showed high accumulation (4.86±1.01 %ID/g, 1h post-intravenous injection (p.i.)) and prolonged retention (4.26±1.23 %ID/g, 24h p.i.) of tracer in PC-3 tumor-bearing mice. Micro-positron emission tomography (microPET) molecular imaging studies produced high-quality, high contrast images in PC-3 tumor-bearing mice at 4h p.i.
CONCLUSIONS
The favorable pharmacokinetics and enhanced tumor uptake of (64)Cu-NOTA-RGD-Glu-6Ahx-RM2 warrant further investigations for dual integrin and GRPr-positive tumor imaging and possible radiotherapy.
简介
在本研究中，我们描述了一种（64）Cu 标记的异双体肽缀合物，用于双重靶向 αvβ3/GRPr（αvβ3 整联蛋白/胃泌素释放肽受体），形式为 [RGD-Glu-[(64)Cu-NO2A]-6-Ahx-RM2]（RGD：氨基酸序列 [Arg-Gly-Asp]，一种用于靶向 αvβ3 整联蛋白受体的非调节肽；Glu：谷氨酸；NO2A：1,4,7-三氮杂环壬烷-1,4-二乙酸；6-Ahx：6-氨基己酸；和 RM2：（D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2），一种用于靶向 GRPr 的 Bombesin（BBN）肽的拮抗剂类似物）。
方法
RGD-Glu-6Ahx-RM2]与 NOTA（1,4,7-三氮杂环壬烷-1,4,7-三乙酸）络合剂缀合，得到 [RGD-Glu-[NO2A]-6-Ahx-RM2]，通过反相高效液相色谱（RP-HPLC）进行纯化，并通过电喷雾电离质谱（ESI-MS）进行表征。用（64）Cu 对缀合物进行放射性标记，得到 [RGD-Glu-[(64)Cu-NO2A]-6-Ahx-RM2]，放射化学产率≥95%。在正常 CF-1 小鼠和 PC-3 人前列腺癌实验模型中研究了放射性标记肽缀合物的体内行为。
结果
用人前列腺 PC-3 细胞中的竞争性置换受体结合测定法，使用（125）I-[Tyr（4）]BBN 作为放射性配体，表明 [RGD-Glu-[(nat)Cu-NO2A]-6-Ahx-RM2] 缀合物对 GRPr 的高结合亲和力（3.09±0.34 nM）。用人、神经胶质瘤 U87-MG 细胞中的类似测定法，使用（125）I-Echistatin 作为放射性配体，表明对 αvβ3 整联蛋白的中等受体结合亲和力（518±37.5 nM）。[RGD-Glu-[(64)Cu-NO2A]-6-Ahx-RM2]的体内研究表明，在 PC-3 肿瘤荷瘤小鼠中，示踪剂在 1 小时静脉注射（p.i.）后具有高的积累（4.86±1.01%ID/g）和延长的保留（4.26±1.23%ID/g，24h p.i.）。微正电子发射断层扫描（microPET）分子成像研究在 PC-3 肿瘤荷瘤小鼠中产生了高质量、高对比度的图像，在 4h p.i.时。
结论
（64）Cu-NOTA-RGD-Glu-6Ahx-RM2 的良好药代动力学和增强的肿瘤摄取，为双重整联蛋白和 GRPr 阳性肿瘤成像和可能的放射治疗提供了进一步的研究。
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