Abstract | UNLABELLED: The overexpression of integrin α(2)β(1) has been demonstrated to correlate with prostate tumor aggressiveness and metastatic potential. Recently, we reported that the DGEA peptide is a promising targeting ligand for near-infrared fluorescence and microPET imaging of integrin α(2)β(1) expression in prostate cancers. Here, we aimed to further improve the targeting efficacy of this peptide by incorporating a series of cell-penetrating peptides (CPPs) into the DGEA sequence. METHODS: After the conjugation with appropriate fluorescent dyes, the CPP-DGEA peptides were evaluated in human prostate cell lines (PC-3, CWR-22, and LNCaP) that contain different integrin α(2)β(1) expression levels. In addition, to reduce excess kidney uptake, a carboxypeptidase-specific sequence Gly-Lys was incorporated into the probe design, allowing for cleavage by the kidney brush border enzymes of the CPP before uptake by proximal tubule cells. RESULTS: Although the CPP motif greatly facilitated the translocation of CPP-DGEA without affecting binding specificity in vitro, fluorescent dye-labeled CPP-DGEA demonstrated extremely high kidney uptake in vivo. Kidney uptake was dramatically decreased after a carboxypeptidase-specific peptide linker ( Gly-Lys) had been incorporated into the probe design. The optimized probe demonstrated a prominent accumulation of activity in PC-3 tumor (integrin α(2)β(1)-positive). Receptor specificity was confirmed with blocking experiments and evaluation in a CWR-22 control tumor model with low α(2)β(1) expression. CONCLUSION: This study demonstrated that the introduction of a CPP sequence can facilitate the internalization of an integrin-targeted peptide probe in vitro. Moreover, a cleavable peptide linker successfully reduced kidney uptake while preserving good tumor uptake in vivo.
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Authors | Chiun-Wei Huang, Zibo Li, Peter S Conti |
Journal | Journal of nuclear medicine : official publication, Society of Nuclear Medicine
(J Nucl Med)
Vol. 52
Issue 12
Pg. 1979-86
(Dec 2011)
ISSN: 1535-5667 [Electronic] United States |
PMID | 22065876
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
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Chemical References |
- Cell-Penetrating Peptides
- Fluorescent Dyes
- Integrin alpha2beta1
- Oligopeptides
- aspartyl-glycyl-glutamyl-alanine
|
Topics |
- Biological Transport
- Cell Line, Tumor
- Cell-Penetrating Peptides
(metabolism)
- Fluorescent Dyes
(metabolism)
- Humans
- Infrared Rays
- Integrin alpha2beta1
(metabolism)
- Kidney
(metabolism)
- Male
- Molecular Imaging
(methods)
- Oligopeptides
(metabolism)
- Optical Phenomena
- Prostatic Neoplasms
(pathology)
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