PT  - JOURNAL ARTICLE
AU  - Shi, Jiyun
AU  - Luo, Haiming
AU  - Fan, Di
AU  - Zhao, Huiyun
AU  - Zhang, Zhihong
AU  - Wang, Fan
TI  - 125I-Labeled octavalent-RGD peptide fluorescent nanoprobe for dual SPECT and optical imaging of integrin αvβ3 receptors in human giloblastoma xenografts
DP  - 2013 May 01
TA  - Journal of Nuclear Medicine
PG  - 1164--1164
VI  - 54
IP  - supplement 2
4099  - http://jnm.snmjournals.org/content/54/supplement_2/1164.short
4100  - http://jnm.snmjournals.org/content/54/supplement_2/1164.full
SO  - J Nucl Med2013 May 01; 54
AB  - 1164 Objectives Recently, we reported a new class of octavalent peptide fluorescent nanoprobe (Octa-FNP) platform, which is composed of targeting peptides and a tetrameric far-red fluorescent protein (tfRFP) scaffold. Herein, we evaluated 125I-labeled octavalent-RGD peptide FNP for dual SPECT and optical imaging of integrin αvβ3 receptors in human giloblastoma xenografts. Furthermore, a linker (L) was introduced to improve the in vivo pharmacokinetics of the nanoprobe(Octa-(L)-FNP). Methods 125I-FNP-L-RGD, 125I-FNP-RGD, 125I-tfRFP and 125I-c(RGDyK) were synthesized, their tumor targeting ability and in vivo characteristics were evaluated in U87-MG human glioblastoma tumor mice by performing cell binding, γ imaging, optical imaging, blood clearance and biodistribution studies. Results Both FNP-RGD and FNP-L-RGD had a significantly higher cellular binding capability than tfRFP. Optical imaging at 6 h p.i. (post-injection) revealed a notable accumulation of FNP-RGD in the U87-MG tumor, however the fluorescence was undetectable in other groups when compared with the same amount injected dose. The γ-imaging at 6 and 24 h p.i. showed that both 125I-FNP-RGD and 125I-FNP-L-RGD had relatively higher tumor uptake than that of 125I-tfRFP and 125I-c(RGDyK), respectively. Moreover, γ-imaging at 24 h p.i. revealed a remarkable accumulation of 125I-FNP-RGD in the tumor while maintaining an extremely low background contrast, suggesting longer tumor retention compared with other groups. The blocking study showed a significant decrease in tumor uptake, indicating it's integrin αvβ3 mediated. Conclusions These data suggested that, as an engineered and multivalent platform, FNP-RGD could enhance the tumor targeting of the RGD-sequence peptide and provide an excellent contrast for the optical and nuclear imaging, making it a valuable tool for cancer theranostics.