Synthesis, in vitro, and in vivo characterization of an integrin alpha(V)beta 3-targeted molecular probe for optical imaging of tumor

Molecular Imaging Laboratory, Clinical Center, National Institutes of Allergies and Infectious Diseases, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
Bioorganic & Medicinal Chemistry (Impact Factor: 2.95). 07/2005; 13(11):3763-71. DOI: 10.1016/j.bmc.2005.03.024
Source: PubMed

ABSTRACT Integrin alpha(v)beta(3) is a widely-recognized target for the development of targeted molecular probes for imaging pathological conditions. alpha(v)beta(3) is a cell-surface receptor protein that is upregulated in various pathological conditions including osteoporosis, rheumatoid arthritis, macular degeneration, and cancer. The synthesis of an alpha(v)beta(3)-targeted optical probe 7 from compound 1, and its in vitro and in vivo characterization is described. A series of aliphatic carbamate derivatives of the potent non-peptide integrin antagonist 1 was synthesized and the binding affinity to alpha(v)beta(3) was determined in both enzyme linked immunosorbent assay (ELISA) and cell adhesion inhibition assays. The hydrophobic carbamate-linked appendages improved the binding affinity of the parent compound for alpha(v)beta(3) by 2-20 times. A Boc-protected neopentyl derivative in the series is shown to have the best binding affinity to alpha(v)beta(3) (IC(50)=0.72 nM) when compared to compound 1 as well as to c-RGDfV. Optical probe 7 utilizes the neopentyl linker and demonstrates increased binding affinity and significant tumor cell uptake in vitro as well as specific tumor accumulation and retention in vivo. These results illustrate the potential of employing integrin-targeted molecular probes based on 1 to image a multitude of diseases associated with alpha(v)beta(3) overexpression.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Rapid one-step 18F labeling reaction with fluoridealuminum complex, which based on chelation chemistry, has been a surge of interest for 18F radiolabeling of peptide. In this study, a non-peptidic bivalent integrin αvβ3 antagonist (bivalent-IA) was conjugated with 1,4,7-triazacyclononane-1,4-diiacetic acid (NODA). A novel 18F labeled radiotracer, 18F-bivalent-IA, was developed via one step 18F-AlF/NODA chelation reaction in aqueous phase with high radiochemical yield (65-75%, decay corrected) and good specific activity (750-850 mCi/μmol). The tumor integrin targeting efficiency and in vivo pharmacokinetic profile of 18F-bivalent-IA was evaluated in U-87 MG (integrin positive) and MDA-MB-231 (integrin negative) models by small-animal PET/CT scan following biodistribution study. The PET/CT and ROIs results showed high tumor uptake of 18F-bivalent-IA in U-87 MG tumor-bearing mice from 5 to 120 min p.i. with good contrast, and the U-87 MG tumor uptake values (6.35 ± 0.67 %ID/g, at 1 h p.i.) was 6 times higher than that of MDA-MB-231 tumor (1.05 ± 0.12 %ID/g, at 1 h p.i.) (P < 0.0001) which correlated with the integrin αvβ3 expression in tumor tissues confirmed by immunohistochemistry. Co-injection of the 18F-bivalent-IA with 6 nmol (6 μg) of nonradioactive bivalent-IA effectively blocked tumor uptake demonstrating the integrin αvβ3-specificity. In conclusion, the first 18F labeled non-peptidic bivalent integrin αvβ3 targeting radiotracer, 18F-bivalent-IA was developed and proved to be a highly potent and specific PET radiopharmaceutical for noninvasively imaging of integrin αvβ3, which plays a critical role in tumor angiogenesis and metastasis.
    Bioconjugate Chemistry 12/2014; DOI:10.1021/bc500590f · 4.82 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Integrins such as αvβ3, α5β1 play a key role in angiogenesis regulation, invasion and metastasis, inflammation, wound healing, etc. The up-regulation of integrin αvβ3 after cerebral ischemic stroke can promote angiogenesis, which in turn improves functional recovery. In addition, the integrin αvβ3 inhibitor can block the blood-brain barrier (BBB) leakage induced by vascular endothelial growth factor (VEGF) and also can reduce inflammatory reaction, decrease the deposition of fibrinogen. Other studies showed that integrin αvβ3 is not essential in revascularization. Therefore, the effect of integrin αvβ3 in the whole process of brain function recovery merits further study.
    Journal of Huazhong University of Science and Technology 06/2014; 34(3):299-305. DOI:10.1007/s11596-014-1274-4 · 0.78 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: n this study, l-thyroxine was covalently grafted on 25 kDa branched polyethylenimine (PEI), and the ability of the nano-sized polyplexes for transferring plasmid encoding interleukin-12 (IL-12) gene was evaluated. As there are several problems in systemic administration of recombinant IL-12 protein, local expression of the plasmid encoding IL-12 gene inside the tumor tissue has been considered as an effective alternative approach. The l-thyroxine-conjugated PEI polyplexes were prepared using pUMVC3-hIL12 plasmid, and their transfection activity was determined in HepG2 human liver carcinoma and Neuro2A neuroblastoma cell lines. The polyplexes characterized in terms of DNA condensation ability, particle size, zeta potential, and buffering capacity as well as cytotoxicity and resistance to enzyme digestion. The results revealed that l-thyroxine conjugation of PEI increased gene transfer ability by up to two fold relative to unmodified 25 kDa PEI, the gold standard for non-viral gene delivery, with the highest increase occurring at degrees of conjugation around 10 %. pDNA condensation tests and dynamic light scattering measurements exhibited the ability of PEI conjugates to optimally condense the plasmid DNA into polyplexes in the size range around 200 nm. The modified polymers showed remarkable buffering capacity and protection against enzymatic degradation comparable to that of unmodified PEI. These results suggest that l-thyroxine conjugation of PEI is a simple modification strategy for future investigations aimed at developing a targeting gene vehicle.
    Journal of Nanoparticle Research 05/2014; 16(16). DOI:10.1007/s11051-014-2423-1 · 2.18 Impact Factor