In vivo near-infrared fluorescence imaging of integrin a,αvβ3 in brain tumor xenografts
In vivo near-infrared fluorescence imaging of integrin a,αvβ3 in brain tumor xenografts
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DOI：
10.1158/0008-5472.can-04-1956
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发表时间：
2004-11-01
期刊：
影响因子：
11.2
通讯作者：
Moats, RA
中科院分区：
文献类型：
--
作者：
Chen, XY;Conti, PS;Moats, RA
通过在各种临床前肿瘤模型中使用放射性核素成像方式，对细胞黏附分子α(v)β(3)整合素在体内表达的无创可视化已进行了充分研究。文献调研表明，此前没有将菁染料用作肿瘤整合素体内光学检测的造影剂。在此，我们报道了新型肽 - 染料偶联物精氨酸 - 甘氨酸 - 天冬氨酸（RGD）- Cy5.5作为造影剂在体外、体内和离体情况下对整合素受体的特异性。RGD - Cy5.5对α(v)β(3)整合素表现出中等亲和力（半数抑制浓度IC50 = 58.1 ± 5.6 nmol/L）。该偶联物导致表达整合素的肿瘤细胞和内皮细胞上的细胞相关荧光升高，并且当与c(RGDyK)共孵育时产生极弱的细胞荧光。使用原型三维小动物成像系统进行体内成像，通过尾静脉给予多种浓度的荧光探针后，可对皮下U87MG胶质母细胞瘤异种移植物进行可视化。由于高剂量时受体特异性肿瘤摄取存在部分自我抑制，低剂量时存在大量背景荧光，在注射后30分钟到24小时内，中等剂量（0.5 nmol）比高剂量（3 nmol）和低剂量（0.1 nmol）产生更好的肿瘤对比度。肿瘤对比度还取决于小鼠的观察角度。未标记的c(RGDyK)可阻断RGD - Cy5.5在肿瘤中的摄取。这项研究表明，RGD肽/整合素相互作用的特异性与近红外荧光检测相结合，可应用于整合素表达的无创成像以及监测抗整合素治疗效果，提供近乎实时的测量。
Noninvasive visualization of cell adhesion molecule alpha(v)beta(3) integrin expression in vivo has been well studied by using the radionuclide imaging modalities in various preclinical tumor models. A literature survey indicated no previous use of cyanine dyes as contrast agents for in vivo optical detection of tumor integrin. Herein, we report the integrin receptor specificity of novel peptide-dye conjugate arginine-glycine-aspartic acid (RGD)-Cy5.5 as a contrast agent in vitro, in vivo, and ex vivo. The RGD-Cy5.5 exhibited intermediate affinity for alpha(v)beta(3) integrin (IC50 = 58.1 +/- 5.6 nmol/L). The conjugate led to elevated cell-associated fluorescence on integrin-expressing tumor cells and endothelial cells and produced minimal cell fluorescence when coincubated with c(RGDyK). In vivo imaging with a prototype three-dimensional small-animal imaging system visualized subcutaneous U87MG lioblastoma xenograft with a 9 broad range of concentrations of fluorescent probe administered via the tail vein. The intermediate dose (0.5 nmol) produces better tumor contrast than high dose (3 nmol) and low dose (0.1 nmol) during 30 minutes to 24 hours postinjection, because of partial self-inhibition of receptor-specific tumor uptake at high dose and the presence of significant amount of background fluorescence at low dose, respectively. The tumor contrast was also dependent on the mouse viewing angles. Tumor uptake of RGD-Cy5.5 was blocked by unlabeled c(RGDyK). This study suggests that the combination of the specificity of RGD peptide/integrin interaction with near-infrared fluorescence detection may be applied to noninvasive imaging of integrin expression and monitoring anti-integrin treatment efficacy providing near real-time measurements.