Evaluation of an Integrin αvβ3 and Aminopeptidase N Dual-Receptor Targeting Tracer for Breast Cancer Imaging.

Abstract

Integrin αvβ3 and aminopeptidase N (APN, also known as CD13) are two important targets involved in the regulation of angiogenesis, tumor proliferation, invasion, and metastasis. In this study, we developed a heterodimeric tracer consisting of arginine-glycine-aspartic (RGD) and asparagine-glycine-arginine (NGR) peptides targeting αvβ3 and CD13, respectively, for PET imaging of breast cancer. The NGR peptide was first modified with N3-NOtB2 and then conjugated to BCN-PEG4-c(RGDyK) via copper-free click chemistry. The resulting precursor was purified and radiolabeled with gallium-68. Small-animal PET/CT imaging and post-imaging biodistribution studies were performed in mice bearing human breast cancer MCF-7, MDA-MB-231, MDA-MB-468, and MX-1 xenografts and pulmonary metastases models. The expression levels of αvβ3 and CD13 in tumors were checked via immunochemical staining. The heterodimeric tracer was successfully synthesized and radiolabeled with gallium-68 at a molar activity of 45-100 MBq/nmol at the end of synthesis. It demonstrated high in vitro and in vivo stability. In static PET/CT imaging studies, the MCF-7 tumor could be clearly visualized and exhibited higher uptake at 30 min post injection of 68Ga-NGR-RGD than that of either 68Ga-RGD or 68Ga-NGR alone. High specificity was shown in blocking studies using Arg-Gly-Asp (RGD) and Asp-Gly-Arg (NGR) peptides. The MCF-7 tumor exhibited the highest uptake of 68Ga-NGR-RGD followed by MDA-MB-231, MDA-MB-468, and MX-1 tumors. This was consistent with their expression levels of CD13 and αvβ3 as confirmed by western blot and immunohistochemical staining. Metastatic lesions in the lungs were clearly detectable on 68Ga-NGR-RGD PET/CT imaging in mouse models of pulmonary metastases. 68Ga-NGR-RGD, a CD13 and αvβ3 dual-receptor targeting tracer, showed higher binding avidities, targeting efficiency, and longer tumor retention time compared with monomeric 68Ga-NGR and 68Ga-RGD. Its promising in vivo performance makes it an ideal candidate for future clinical translation.

• Authors: Yongkang Gai, Yaqun Jiang, Yu Long, Lingyi Sun, Qingyao Liu, Chunxia Qin, Yongxue Zhang, Dexing Zeng, Xiaoli Lan
• Journal: Molecular pharmaceutics (Mol Pharm) Vol. 17 Issue 1 Pg. 349-358 (01 06 2020) ISSN: 1543-8392 [Electronic] United States
• PMID: 31829615 (Publication Type: Evaluation Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Gallium Radioisotopes
• Integrin alphaVbeta3
• Oligopeptides
• Radiopharmaceuticals
• asparagine-glycine-arginine
• arginyl-glycyl-aspartic acid
• Gallium-68
• CD13 Antigens

Topics

• Animals
• Breast Neoplasms (diagnostic imaging, metabolism, pathology)
• CD13 Antigens (antagonists & inhibitors, metabolism)
• Cell Line, Tumor
• Female
• Gallium Radioisotopes
• Humans
• Integrin alphaVbeta3 (antagonists & inhibitors, metabolism)
• Lung Neoplasms (diagnostic imaging, metabolism, secondary)
• Mice
• Mice, Inbred BALB C
• Mice, Nude
• Oligopeptides (chemistry)
• Positron Emission Tomography Computed Tomography
• Radiopharmaceuticals (administration & dosage, chemistry, metabolism, pharmacokinetics)
• Tissue Distribution
• Xenograft Model Antitumor Assays