Integrin α_vβ₃ is an effective marker of angiogenesis in cancer, and α_vβ₃-specific imaging can yield important details about this complex physiological process. We utilized the recently reported and highly α_vβ₃-specific peptide, bicyclic RGD (bcRGD), as the basic structure of an in vivo α_vβ₃ imaging probe, and synthesized a radioiodinated form of bcRGD, namely [¹²⁵I]bcRGD, with high radiochemical purity (>99%) and high molar activity (81 GBq/μmol). As expected, [¹²⁵I]bcRGD exhibited high selectivity for α_vβ₃ compared with α_vβ₅ and α₅β₁ in vitro. [¹²⁵I]bcRGD showed significantly higher accumulation in U-87MG cells (1.6% dose/mg) with high expression of α_vβ₃ compared to A549 cells (0.3% dose/mg) with only moderate expression. Furthermore, 30 min after administration to tumor-bearing mice, [¹²⁵I]bcRGD showed significantly higher accumulation in U-87MG tumors (3.8% ID/g) than in A549 tumors (2.1% ID/g), and the radioactivity accumulation ratios of U-87MG tumor/blood and U-87MG tumor/muscle were 4.0 and 6.0, respectively. These results highlight the promising properties of [^123/125I]bcRGD for use as an in vivo α_vβ₃ imaging probe, as well as the utility of bcRGD as a basic structure of molecular probes for both imaging and therapeutic applications. bcRGD may exhibit broad use in future theranostics applications targeting integrin α_vβ₃-related diseases.

整合素α _v β ₃是在癌症的血管生成的有效标记，α _v β ₃特异性成像可以产生关于这个复杂的生理过程的重要细节。我们利用最近报道和高度α _v β ₃特异性肽，双环RGD（bcRGD），作为一个基本结构体内α _v β ₃成像探头，并合成bcRGD的放射性碘标记的形式，即[ ¹²⁵ I] bcRGD ，具有高放射化学纯度（> 99％）和高摩尔活性（81 GBq /μmol）。如所预期的，[ ¹²⁵ I]显示出bcRGD高选择性α _v β ₃与α相比_v β ₅和α ₅ β ₁ 在体外。[ ¹²⁵ I] bcRGD显示以U-87MG细胞与α的高表达显著更高积累（1.6％剂量/毫克）_v β ₃相比A549细胞（0.3％剂量/毫克）与仅中度表达。此外，在对荷瘤小鼠给药后30分钟，[ ¹²⁵ I] bcRGD在U-87MG肿瘤（3.8％ID / g）中的蓄积明显高于在A549肿瘤（2.1％ID / g）中的蓄积，并且放射性蓄积率U-87MG肿瘤/血液和U-87MG肿瘤/肌肉的分别为4.0和6.0。这些结果突出了[ ^123/125I] bcRGD用作体内α _v β ₃的成像探头，以及bcRGD作为分子探针的用于成像和治疗应用中的基本结构的实用程序。bcRGD可以表现出在未来治疗诊断学应用靶向整合素α广泛使用_v β _3种相关疾病。