Evaluation of a maleimido derivative of NOTA for site-specific labeling of affibody molecules.
Bioconjug Chem
; 22(5): 894-902, 2011 May 18.
Article
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| MEDLINE
| ID: mdl-21443270
ABSTRACT
Radionuclide molecular imaging has the potential to improve cancer treatment by selection of patients for targeted therapy. Affibody molecules are a class of small (7 kDa) high-affinity targeting proteins with appreciable potential as molecular imaging probes. The NOTA chelator forms stable complexes with a number of radionuclides suitable for SPECT or PET imaging. A maleimidoethylmonoamide NOTA (MMA-NOTA) has been prepared for site-specific labeling of Affibody molecules having a unique C-terminal cysteine. Coupling of the MMA-NOTA to the anti-HER2 Affibody molecule Z(HER22395) resulted in a conjugate with an affinity (dissociation constant) to HER2 of 72 pM. Labeling of [MMA-NOTA-Cys(61)]-Z(HER22395) with (111)In gave a yield of >95% after 20 min at 60 °C. In vitro cell tests demonstrated specific binding of [(111)In-MMA-NOTA-Cys(61)]-Z(HER22395) to HER2-expressing cell lines. In mice bearing prostate cancer DU-145 xenografts, the tumor uptake of [(111)In-MMA-NOTA-Cys(61)]-Z(HER22395) was 8.2 ± 0.9% IA/g and the tumor-to-blood ratio was 31 ± 1 (4 h postinjection). DU-145 xenografts were clearly visualized by a gamma camera. Direct in vivo comparison of [(111)In-MMA-NOTA-Cys(61)]-Z(HER22395) and [(111)In-MMA-DOTA-Cys(61)]-Z(HER22395) demonstrated that both conjugates provided equal radioactivity uptake in tumors, but the tumor-to-organ ratios were better for [(111)In-MMA-NOTA-Cys(61)]-Z(HER22395) due to more efficient clearance from normal tissues. In conclusion, coupling of MMA-NOTA to a cysteine-containing Affibody molecule resulted in a site-specifically labeled conjugate, which retains high affinity, can be efficiently labeled, and allows for high-contrast imaging.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Coloración y Etiquetado
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Proteínas Recombinantes de Fusión
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Radiofármacos
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Imagen Molecular
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Compuestos Heterocíclicos
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Maleimidas
Límite:
Animals
Idioma:
En
Revista:
Bioconjug Chem
Asunto de la revista:
BIOQUIMICA
Año:
2011
Tipo del documento:
Article
País de afiliación:
Suecia