Estefanía Sicco1, Jessica Baez1, Manuel Ibarra2, Marcelo Fernández3, Pablo Cabral1, María Moreno4, Hugo Cerecetto1, Victoria Calzada1. 1. Departamento de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay. 2. Departamento de Ciencias Farmaceuticas, Facultad de Química, Universidad de la República, Montevideo, Uruguay. 3. Laboratorio de Experimentacion Animal, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay. 4. Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
Abstract
Background: Aptamers represent an emerging class of oligonucleotides that have the ability to bind ligands with high affinity. Sgc8-c aptamer recognizes PTK7, a member of the catalytically defective receptor protein tyrosine kinase family that is upregulated in various cancers, including hemato-oncological malignancies. Herein, an Sgc8-c-NOTA-radiolabeled probe was prepared for theranostic purpose. Materials and Methods: In this work, an Sgc8-c-radiolabeled probe against PTK7 was prepared, and biological evaluations-pharmacokinetic studies, biodistribution analysis, and in vivo molecular imaging-were performed. To obtain the radiolabeled probe, a modified 5'-amino-derivative of the Sgc8-c aptamer was bound to the metal chelator NOTA, and subsequently labeled with 67Ga with high yield and radiochemical purity. The precursor, Sgc8-c-NOTA, the radio probe Sgc8-c-NOTA-67Ga, and its nonradioactive complex, Sgc8-c-NOTA-69/71Ga, were purified by reverse-phase high-performance liquid chromatography and characterized by electrospray ionization mass spectrometry. The binding ability of Sgc8-c-NOTA-67Ga was studied in vitro against purified PTK7 receptor. In addition, the binding was also evidenced against the hemato-oncological A20 cell line, derived from B lymphocytes, and the corresponding A20-green fluorescent protein (GFP)-transfected cells. The proof of concept was performed on A20-GFP tumor-bearing mice, in which the biodistribution of the radiolabeled probe was evaluated through imaging, using X-ray, fluorescence, and γ modalities. The specific uptake of the probe was confirmed by blocking with the Sgc8-c aptamer in an in vivo competition assay. Results: The biodistribution results showed considerable uptake in tumor since 2 h, with highest at 48 h postinjection. However, the blood and muscle ID/g (injected dose per gram of tissue) activities were decreasing with time and tumor/no-target ratios increasing to 20 at 24 h postinjection. These results are consistent with the in vivo images. Conclusions: This study supports the utility of Sgc8-c-NOTA radiolabeled as a theranostic agent.
Background: Aptamers represent an emerging class of oligonucleotides that have the ability to bind ligands with high affinity. Sgc8-c aptamer recognizes PTK7, a member of the catalytically defective receptor protein tyrosine kinase family that is upregulated in various cancers, including hemato-oncological malignancies. Herein, an Sgc8-c-NOTA-radiolabeled probe was prepared for theranostic purpose. Materials and Methods: In this work, an Sgc8-c-radiolabeled probe against PTK7 was prepared, and biological evaluations-pharmacokinetic studies, biodistribution analysis, and in vivo molecular imaging-were performed. To obtain the radiolabeled probe, a modified 5'-amino-derivative of the Sgc8-c aptamer was bound to the metal chelator NOTA, and subsequently labeled with 67Ga with high yield and radiochemical purity. The precursor, Sgc8-c-NOTA, the radio probe Sgc8-c-NOTA-67Ga, and its nonradioactive complex, Sgc8-c-NOTA-69/71Ga, were purified by reverse-phase high-performance liquid chromatography and characterized by electrospray ionization mass spectrometry. The binding ability of Sgc8-c-NOTA-67Ga was studied in vitro against purified PTK7 receptor. In addition, the binding was also evidenced against the hemato-oncological A20 cell line, derived from B lymphocytes, and the corresponding A20-green fluorescent protein (GFP)-transfected cells. The proof of concept was performed on A20-GFP tumor-bearing mice, in which the biodistribution of the radiolabeled probe was evaluated through imaging, using X-ray, fluorescence, and γ modalities. The specific uptake of the probe was confirmed by blocking with the Sgc8-c aptamer in an in vivo competition assay. Results: The biodistribution results showed considerable uptake in tumor since 2 h, with highest at 48 h postinjection. However, the blood and muscle ID/g (injected dose per gram of tissue) activities were decreasing with time and tumor/no-target ratios increasing to 20 at 24 h postinjection. These results are consistent with the in vivo images. Conclusions: This study supports the utility of Sgc8-c-NOTA radiolabeled as a theranostic agent.
Authors: Ana Paula Arévalo; Romina Castelli; Manuel Ibarra; Martina Crispo; Victoria Calzada Journal: Int J Mol Sci Date: 2022-02-23 Impact factor: 5.923