TY - JOUR
T1 - Activatable iRGD-based peptide monolith
T2 - Targeting, internalization, and fluorescence activation for precise tumor imaging
AU - Cho, Hong Jun
AU - Lee, Sung Jin
AU - Park, Sung Jun
AU - Paik, Chang H.
AU - Lee, Sang Myung
AU - Kim, Sehoon
AU - Lee, Yoon Sik
N1 - Funding Information:
This work was supported by grants from the National Research Foundation of Korea ( 2012K1A1A2A01055811 ), the Korea Health Industry Development Institute ( HI15C1540 ), the Development of Platform Technology for Innovative MedicalMeasurements Program ( GP2016-0022 ) from the Korea Research Institute of Standards and Science , the Intramural Research Program of KIST , Basic Science Research Program funded by the Ministry of Science, ICT & Future Planning and National Research Foundation of Korea ( NRF-2014R1A1A1006711 ), and the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science, ICT and Future Planning ( NRF-2015M2B2A6028602 ).
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/9/10
Y1 - 2016/9/10
N2 - A disulfide-bridged cyclic RGD peptide, named iRGD (internalizing RGD, c(CRGDK/RGPD/EC)), is known to facilitate tumor targeting as well as tissue penetration. After the RGD motif-induced targeting on αv integrins expressed near tumor tissue, iRGD encounters proteolytic cleavage to expose the CendR motif that promotes penetration into cancer cells via the interaction with neuropilin-1. Based on these proteolytic cleavage and internalization mechanism, we designed an iRGD-based monolithic imaging probe that integrates multiple functions (cancer-specific targeting, internalization and fluorescence activation) within a small peptide framework. To provide the capability of activatable fluorescence signaling, we conjugated a fluorescent dye to the N-terminal of iRGD, which was linked to the internalizing sequence (CendR motif), and a quencher to the opposite C-terminal. It turned out that fluorescence activation of the dye/quencher-conjugated monolithic peptide probe requires dual (reductive and proteolytic) cleavages on both disulfide and amide bond of iRGD peptide. Furthermore, the cleavage of the iRGD peptide leading to fluorescence recovery was indeed operative depending on the tumor-related angiogenic receptors (αvβ3 integrin and neuropilin-1) in vitro as well as in vivo. Compared to an ‘always fluorescent’ iRGD control probe without quencher conjugation, the dye/quencher-conjugated activatable monolithic peptide probe visualized tumor regions more precisely with lower background noise after intravenous injection, owing to the multifunctional responses specific to tumor microenvironment. All these results, along with minimal in vitro and in vivo toxicity profiles, suggest potential of the iRGD-based activatable monolithic peptide probe as a promising imaging agent for precise tumor diagnosis.
AB - A disulfide-bridged cyclic RGD peptide, named iRGD (internalizing RGD, c(CRGDK/RGPD/EC)), is known to facilitate tumor targeting as well as tissue penetration. After the RGD motif-induced targeting on αv integrins expressed near tumor tissue, iRGD encounters proteolytic cleavage to expose the CendR motif that promotes penetration into cancer cells via the interaction with neuropilin-1. Based on these proteolytic cleavage and internalization mechanism, we designed an iRGD-based monolithic imaging probe that integrates multiple functions (cancer-specific targeting, internalization and fluorescence activation) within a small peptide framework. To provide the capability of activatable fluorescence signaling, we conjugated a fluorescent dye to the N-terminal of iRGD, which was linked to the internalizing sequence (CendR motif), and a quencher to the opposite C-terminal. It turned out that fluorescence activation of the dye/quencher-conjugated monolithic peptide probe requires dual (reductive and proteolytic) cleavages on both disulfide and amide bond of iRGD peptide. Furthermore, the cleavage of the iRGD peptide leading to fluorescence recovery was indeed operative depending on the tumor-related angiogenic receptors (αvβ3 integrin and neuropilin-1) in vitro as well as in vivo. Compared to an ‘always fluorescent’ iRGD control probe without quencher conjugation, the dye/quencher-conjugated activatable monolithic peptide probe visualized tumor regions more precisely with lower background noise after intravenous injection, owing to the multifunctional responses specific to tumor microenvironment. All these results, along with minimal in vitro and in vivo toxicity profiles, suggest potential of the iRGD-based activatable monolithic peptide probe as a promising imaging agent for precise tumor diagnosis.
KW - Activatable probe
KW - Internalizing RGD (iRGD)
KW - Peptide monolith
KW - Tumor imaging
UR - http://www.scopus.com/inward/record.url?scp=84978388546&partnerID=8YFLogxK
U2 - 10.1016/j.jconrel.2016.06.032
DO - 10.1016/j.jconrel.2016.06.032
M3 - Article
C2 - 27349354
AN - SCOPUS:84978388546
SN - 0168-3659
VL - 237
SP - 177
EP - 184
JO - Journal of Controlled Release
JF - Journal of Controlled Release
ER -