Abstract
Previously reported results suggest that the analogue of the somatostatin des-AA 1,2,5[D-Trp 8,IAmp 9]-somatostatin (CH-275) peptide bearing chelating agents able to coordinate radioactive metals could be used for scintigraphic imaging of tumor lesions overexpressing sstr1. An efficient synthetic procedure for the preparation of the somatostatin analogue CH-275 and its conjugate DTPAGlu-Gly-CH-275, bearing the chelating agent DTPAGlu (DTPAGlu = N,N-bis[2-[bis(carboxy-ethyl)amino]ethyl]-L-glutamic acid) on the N-terminus, by solid-phase peptide synthesis and 9-flourenymethyoxycarbonyl (Fmoc) chemistry, is here reported. Rapid and efficient labeling of DTPAGlu-Gly-CH-275 was achieved by addition of IIIIn(III) to the compound. Typical yields were greater than 97% as determined by reversed phase high performance liquid chromatography (HPLC) at specific activities in the range 4-9 GBq/μmol (100-250 Ci/mmol). A preliminary biological assay of the binding ability of IIIIn-DTPAGlu-Gly-CH-275 indicates, however, that the labeled compound does not display any specific interaction with somatostatin sstrl receptors in the tested cell lines. To confirm this unexpected negative result, competition binding experiments were carried out, in which fixed tracer amounts of the 125!-labeled somatostatin-14 were incubated with the receptor-expressing cells in the presence of DTPAGlu-Gly-CH-275 or CH-275 at concentrations ranging from 10 -10 to 10 -3 M. While CH-275 shows a IC 50 of 80 nM similar to that already found in displacement experiments on CHO-Kl sstrl-transfected cells, DTPAGlu-Gly-CH-275 displays instead very low or negligible affinity towards this receptor. The NMR solution characterization indicates that the presence of DTPAGlu does not influence the conformational and chemical features of the peptide moiety, thus suggesting that the loss in binding activity should be due to steric hindrance of either the chelating agent DTPAGlu or its indium complex.
| Original language | English |
|---|---|
| Pages (from-to) | 527-534 |
| Number of pages | 8 |
| Journal | Biopolymers |
| Volume | 76 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 2004 |
Fingerprint
Keywords
- Indium complexes
- NMR
- Nuclear medicine techniques
- Somatostatin analogue
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Biochemistry
- Biophysics
Cite this
Peptide-chelating agent conjugate for selective targeting of somatostatin receptor type 1 : Synthesis and characterization. / Mansi, Rosalba; Tesauro, Diego; De Capua, Antonia; Fattorusso, Roberto; Caracò, Corradina; Aloj, Luigi; Benedetti, Ettore; Morelli, Giancarlo.
In: Biopolymers, Vol. 76, No. 6, 2004, p. 527-534.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Peptide-chelating agent conjugate for selective targeting of somatostatin receptor type 1
T2 - Synthesis and characterization
AU - Mansi, Rosalba
AU - Tesauro, Diego
AU - De Capua, Antonia
AU - Fattorusso, Roberto
AU - Caracò, Corradina
AU - Aloj, Luigi
AU - Benedetti, Ettore
AU - Morelli, Giancarlo
PY - 2004
Y1 - 2004
N2 - Previously reported results suggest that the analogue of the somatostatin des-AA 1,2,5[D-Trp 8,IAmp 9]-somatostatin (CH-275) peptide bearing chelating agents able to coordinate radioactive metals could be used for scintigraphic imaging of tumor lesions overexpressing sstr1. An efficient synthetic procedure for the preparation of the somatostatin analogue CH-275 and its conjugate DTPAGlu-Gly-CH-275, bearing the chelating agent DTPAGlu (DTPAGlu = N,N-bis[2-[bis(carboxy-ethyl)amino]ethyl]-L-glutamic acid) on the N-terminus, by solid-phase peptide synthesis and 9-flourenymethyoxycarbonyl (Fmoc) chemistry, is here reported. Rapid and efficient labeling of DTPAGlu-Gly-CH-275 was achieved by addition of IIIIn(III) to the compound. Typical yields were greater than 97% as determined by reversed phase high performance liquid chromatography (HPLC) at specific activities in the range 4-9 GBq/μmol (100-250 Ci/mmol). A preliminary biological assay of the binding ability of IIIIn-DTPAGlu-Gly-CH-275 indicates, however, that the labeled compound does not display any specific interaction with somatostatin sstrl receptors in the tested cell lines. To confirm this unexpected negative result, competition binding experiments were carried out, in which fixed tracer amounts of the 125!-labeled somatostatin-14 were incubated with the receptor-expressing cells in the presence of DTPAGlu-Gly-CH-275 or CH-275 at concentrations ranging from 10 -10 to 10 -3 M. While CH-275 shows a IC 50 of 80 nM similar to that already found in displacement experiments on CHO-Kl sstrl-transfected cells, DTPAGlu-Gly-CH-275 displays instead very low or negligible affinity towards this receptor. The NMR solution characterization indicates that the presence of DTPAGlu does not influence the conformational and chemical features of the peptide moiety, thus suggesting that the loss in binding activity should be due to steric hindrance of either the chelating agent DTPAGlu or its indium complex.
AB - Previously reported results suggest that the analogue of the somatostatin des-AA 1,2,5[D-Trp 8,IAmp 9]-somatostatin (CH-275) peptide bearing chelating agents able to coordinate radioactive metals could be used for scintigraphic imaging of tumor lesions overexpressing sstr1. An efficient synthetic procedure for the preparation of the somatostatin analogue CH-275 and its conjugate DTPAGlu-Gly-CH-275, bearing the chelating agent DTPAGlu (DTPAGlu = N,N-bis[2-[bis(carboxy-ethyl)amino]ethyl]-L-glutamic acid) on the N-terminus, by solid-phase peptide synthesis and 9-flourenymethyoxycarbonyl (Fmoc) chemistry, is here reported. Rapid and efficient labeling of DTPAGlu-Gly-CH-275 was achieved by addition of IIIIn(III) to the compound. Typical yields were greater than 97% as determined by reversed phase high performance liquid chromatography (HPLC) at specific activities in the range 4-9 GBq/μmol (100-250 Ci/mmol). A preliminary biological assay of the binding ability of IIIIn-DTPAGlu-Gly-CH-275 indicates, however, that the labeled compound does not display any specific interaction with somatostatin sstrl receptors in the tested cell lines. To confirm this unexpected negative result, competition binding experiments were carried out, in which fixed tracer amounts of the 125!-labeled somatostatin-14 were incubated with the receptor-expressing cells in the presence of DTPAGlu-Gly-CH-275 or CH-275 at concentrations ranging from 10 -10 to 10 -3 M. While CH-275 shows a IC 50 of 80 nM similar to that already found in displacement experiments on CHO-Kl sstrl-transfected cells, DTPAGlu-Gly-CH-275 displays instead very low or negligible affinity towards this receptor. The NMR solution characterization indicates that the presence of DTPAGlu does not influence the conformational and chemical features of the peptide moiety, thus suggesting that the loss in binding activity should be due to steric hindrance of either the chelating agent DTPAGlu or its indium complex.
KW - Indium complexes
KW - NMR
KW - Nuclear medicine techniques
KW - Somatostatin analogue
UR - http://www.scopus.com/inward/record.url?scp=10844297906&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=10844297906&partnerID=8YFLogxK
U2 - 10.1002/bip.20169
DO - 10.1002/bip.20169
M3 - Article
C2 - 15526334
AN - SCOPUS:10844297906
VL - 76
SP - 527
EP - 534
JO - Biopolymers
JF - Biopolymers
SN - 0006-3525
IS - 6
ER -