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Comparison of receptor affinity of natSc-DOTA-TATE versus natGa-DOTA-TATE
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Abstract
MATERIAL AND METHODS: The cold complexes of DOTA-TATE with natGa and natSc were synthesized and identified by HPLC and MS analysis and evaluated in vitro for competitive binding to cancer cell line AR42J expressing somatostatin receptors subtype 2 (sstr2).
RESULTS: The IC50 values calculated from the displacement curve of {125I-Tyr11}-SST-14 were: 0.20 ± 0.18, 0.70 ± 0.20, 0.64 ± 0.22 and 0.67 ± 0.12 for natGa-DOTA-TATE, natSc-DOTA-TATE, DOTA-TATE, and {Tyr11}-SST-14 complexes, respectively, with the affinity lowering in the decreasing order: natGa-DOTA-TATE > DOTA-TATE > Tyr11-SST-14 > natSc-DOTA-TATE.
CONCLUSIONS: The binding affinity of natGa-DOTA-TATE appeared higher than that of natSc-DOTA-TATE. Further in vitro and in vivo studies are needed to verify the influence of the chelated metal on the affinity and uptake of the respective radiolabelled compounds. This information might be crucial when the in vivo applications of peptides labelled with 68Ga and 44Sc for PET, as well as the use of 47Sc for radiotherapy are considered.
Nuclear Med Rev 2011; 14, 2: 85–89
Abstract
MATERIAL AND METHODS: The cold complexes of DOTA-TATE with natGa and natSc were synthesized and identified by HPLC and MS analysis and evaluated in vitro for competitive binding to cancer cell line AR42J expressing somatostatin receptors subtype 2 (sstr2).
RESULTS: The IC50 values calculated from the displacement curve of {125I-Tyr11}-SST-14 were: 0.20 ± 0.18, 0.70 ± 0.20, 0.64 ± 0.22 and 0.67 ± 0.12 for natGa-DOTA-TATE, natSc-DOTA-TATE, DOTA-TATE, and {Tyr11}-SST-14 complexes, respectively, with the affinity lowering in the decreasing order: natGa-DOTA-TATE > DOTA-TATE > Tyr11-SST-14 > natSc-DOTA-TATE.
CONCLUSIONS: The binding affinity of natGa-DOTA-TATE appeared higher than that of natSc-DOTA-TATE. Further in vitro and in vivo studies are needed to verify the influence of the chelated metal on the affinity and uptake of the respective radiolabelled compounds. This information might be crucial when the in vivo applications of peptides labelled with 68Ga and 44Sc for PET, as well as the use of 47Sc for radiotherapy are considered.
Nuclear Med Rev 2011; 14, 2: 85–89
Keywords
scandium-44; gallium-68; PET tracers; receptor affinity; DOTA-derivatised peptides
Title
Comparison of receptor affinity of natSc-DOTA-TATE versus natGa-DOTA-TATE
Journal
Issue
Article type
Research paper
Pages
85-89
Published online
2012-01-04
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1367
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2791
Bibliographic record
Nucl. Med. Rev 2011;14(2):85-89.
Keywords
scandium-44
gallium-68
PET tracers
receptor affinity
DOTA-derivatised peptides
Authors
Eftychia Koumarianou
Dariusz Pawlak
Agnieszka Korsak
Renata Mikolajczak