Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba, 263-8555, Japan.
Angiogenesis. 2012 Dec;15(4):569-80. doi: 10.1007/s10456-012-9281-1. Epub 2012 May 29.
64Cu-cyclam-RAFT-c(-RGDfK-)4 is a novel multimeric positron emission tomography (PET) probe for αVβ3 integrin imaging. Its uptake and αVβ3 expression in tumors showed a linear correlation. Since αVβ3 integrin is strongly expressed on activated endothelial cells during angiogenesis, we aimed to determine whether 64Cu-cyclam-RAFT-c(-RGDfK-)4 PET can be used to image tumor angiogenesis and monitor the antiangiogenic effect of a novel multi-targeted tyrosine kinase inhibitor, TSU-68. Athymic nude mice bearing human hepatocellular carcinoma HuH-7 xenografts, which expressed negligible αVβ3 levels on the tumor cells, received intraperitoneal injections of TSU-68 or the vehicle for 14 days. Antiangiogenic effects were determined at the end of therapy in terms of 64Cu-cyclam-RAFT-c(-RGDfK-)4 uptake evaluated using PET, biodistribution assay, and autoradiography, and they were compared with microvessel density (MVD) determined by CD31 immunostaining. 64Cu-cyclam-RAFT-c(-RGDfK-)4 PET enabled clear tumor visualization by targeting the vasculature, and the biodistribution assay indicated high tumor-to-blood and tumor-to-muscle ratios of 31.6 ± 6.3 and 6.7 ± 1.1, respectively, 3 h after probe injection. TSU-68 significantly slowed tumor growth and reduced MVD; these findings were consistent with a significant reduction in the tumor 64Cu-cyclam-RAFT-c(-RGDfK-)4 uptake. Moreover, a linear correlation was observed between tumor MVD and the corresponding standardized uptake value (SUV) (r = 0.829, P = 0.011 for SUV(mean); r = 0.776, P = 0.024 for SUV(max)) determined by quantitative PET. Autoradiography and immunostaining showed that the distribution of intratumoral radioactivity and tumor vasculature corresponded. We concluded that 64Cu-cyclam-RAFT-c(-RGDfK-)4 PET can be used for in vivo angiogenesis imaging and monitoring of tumor response to antiangiogenic therapy.
64Cu-环拉胺-RAFT-c(-RGDfK-)4 是一种新型的多聚正电子发射断层扫描（PET）探针，用于 αVβ3 整联蛋白成像。其在肿瘤中的摄取与 αVβ3 表达呈线性相关。由于 αVβ3 整联蛋白在血管生成过程中强烈表达于活化的内皮细胞，我们旨在确定 64Cu-环拉胺-RAFT-c(-RGDfK-)4 PET 是否可用于成像肿瘤血管生成并监测新型多靶点酪氨酸激酶抑制剂 TSU-68 的抗血管生成作用。携带人肝癌 HuH-7 异种移植瘤的无胸腺裸鼠，其肿瘤细胞上表达的 αVβ3 水平可以忽略不计，在 14 天内接受 TSU-68 或载体的腹腔注射。在治疗结束时，通过 PET 评估的 64Cu-环拉胺-RAFT-c(-RGDfK-)4 摄取、生物分布测定和放射自显影，以及与 CD31 免疫染色确定的微血管密度（MVD）来确定抗血管生成作用。64Cu-环拉胺-RAFT-c(-RGDfK-)4 PET 通过靶向血管系统实现了对肿瘤的清晰可视化，生物分布测定显示，在探针注射后 3 小时，肿瘤与血液和肿瘤与肌肉的比值分别高达 31.6±6.3 和 6.7±1.1。TSU-68 显著减缓肿瘤生长并降低 MVD；这些发现与肿瘤 64Cu-环拉胺-RAFT-c(-RGDfK-)4 摄取的显著减少一致。此外，通过定量 PET 确定的肿瘤 MVD 与相应的标准化摄取值（SUV）之间存在线性相关性（SUV(mean)：r=0.829，P=0.011；SUV(max)：r=0.776，P=0.024）。放射自显影和免疫染色显示，肿瘤内放射性分布与肿瘤血管分布相对应。我们得出结论，64Cu-环拉胺-RAFT-c(-RGDfK-)4 PET 可用于体内血管生成成像和监测肿瘤对抗血管生成治疗的反应。
