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Enzyme-Controlled Intracellular Self-Assembly of (18)F Nanoparticles for Enhanced MicroPET Imaging of Tumor.

Liu Y, Miao Q, Zou P, Liu L, Wang X, An L, Zhang X, Qian X, Luo S, Liang G - Theranostics (2015)

Bottom Line: TEM images of 1-Cold-treated MDA-MB-468 cells directly uncovered that the intracellular 1-Cold-NPs were at/near the location of furin (i.e., Golgi bodies).MTT results indicated that 50 µM 1-Cold did not impose cytotoxicity to MDA-MB-468 cells up to 12 hours.Our ''smart'' probe (i.e., 1), together with the strategy of co-injection, might help researchers trace the biomarkers of interest within a longer time window.

View Article: PubMed Central - PubMed

Affiliation: 1. School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China ; 3. Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu 214063, China.

ABSTRACT
Herein, we report the development of a new "smart" radioactive probe (i.e., 1) which can undergo furin-controlled condensation and self-assembly of radioactive nanoparticles (i.e., 1-NPs) in tumor cells and its application for enhanced microPET imaging of tumors in nude mice co-injected with its cold analog (i.e., 1-Cold). Furin-controlled condensation of 1-Cold and self-assembly of its nanoparticles (i.e., 1-Cold-NPs) in vitro were validated and characterized with HPLC, mass spectra, SEM, and TEM analyses. Cell uptake studies showed that both 1 and 1-Cold have good cell permeability. TEM images of 1-Cold-treated MDA-MB-468 cells directly uncovered that the intracellular 1-Cold-NPs were at/near the location of furin (i.e., Golgi bodies). MTT results indicated that 50 µM 1-Cold did not impose cytotoxicity to MDA-MB-468 cells up to 12 hours. MicroPET imaging of MDA-MB-468 tumor-bearing mice indicated that mice co-injected with 1 and 1-Cold showed higher uptake and longer attenuation of the radioactivity in tumors than those mice only injected with same dosage of 1. Tumor uptake ratios of 1 between these two groups of mice reached the maximum of 8.2 folds at 240 min post injection. Biodistribution study indicated that the uptake ratios of 1 in kidneys between these two groups continuously increased and reached 81.9 folds at 240 min post injection, suggesting the formation of radioactive NPs (i.e., 1-NPs) in MDA-MB-468 tumors of mice co-injected with 1 and 1-Cold. And the nanoparticles were slowly digested and secreted from the tumors, accumulating in the kidneys. Our ''smart'' probe (i.e., 1), together with the strategy of co-injection, might help researchers trace the biomarkers of interest within a longer time window.

No MeSH data available.


Related in: MedlinePlus

Shematic illustration of a furin-controlled condensation of 1 to assemble radioactive nanoparticles in cancer cells. After entering cancer cells, the disulfide bond of probe 1 is reduced by GSH and the RVRR peptide sequence is cleaved by furin to yield the active intermediate 1-Core. Two 1-Cores condense to yield amphiphilic dimers which self-assemble into 1-NPs at or near the locations of furin (i.e., Golgi bodies) in cancer cells.
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SC1: Shematic illustration of a furin-controlled condensation of 1 to assemble radioactive nanoparticles in cancer cells. After entering cancer cells, the disulfide bond of probe 1 is reduced by GSH and the RVRR peptide sequence is cleaved by furin to yield the active intermediate 1-Core. Two 1-Cores condense to yield amphiphilic dimers which self-assemble into 1-NPs at or near the locations of furin (i.e., Golgi bodies) in cancer cells.

Mentions: Our design is illustrated in Scheme 1. Briefly, the SMB probe, Acetyl-Arg-Val-Arg-Arg-Cys(StBu)-Lys(18F-FB)-CBT (1), was designed to have these components as following: (1) a RVRR peptide sequence for cell-membrane-translocation and furin (a protease overexpressed in cancer) cleavage; (2) a disulfided Cys for supplying the 1,2-aminothiol group to condense with the cyano group on the 2-cyanobenzothiazole (CBT) motif; (3) a Lys whose side chain is covalently conjugated with 4-18F-fluorobenzoate (18F-FB) for positron emission tomography (PET) imaging. After entering cancer cells, the disulfide bond of the Cys motif of 1 is reduced by the intracellular glutathione (GSH) and subsequently its RVRR motif is cleaved by furin, resulting in the active intermediate 1-Core. Two 1-Cores quickly condense to yield the amphiphilic oligomers (e.g., dimer of 1-Core, 1-Dimer) which self-assemble into nanoparticles (i.e., 1-NPs) via π-π stacking among each other. As-formed 1-NPs could concentrate the radioactivity inside tumor cells, rendering enhanced PET imaging of tumors. Moreover, the big size and the hydrophobic nature of 1-NPs would prevent themselves from being pumped out by the cells, resulting in longer retention time in cells or longer circulation time in vivo, which is also good for tumor imaging. However, before approaching to furin at Golgi bodies, the cyano group of the radioactive probe 1 at very low chemical concentration (7.1 pmol kg-1 for PET imaging in this work) would condense with intracellular Cys, causing its self-condensation and assembly of 1-NPs infeasible. To resolve this, we have demonstrated that co-incubation of the radioactive probe (e.g., 1 herein) with its cold analog (e.g., 1-Cold herein Figure 1) above 25 µM would conquer intracellular Cys and warrant the self-assembly of the radioactive nanoparticles inside cells 44. In this paper, we designed 1-Cold for the co-injection with 1 into nude mice xenografted with MDA-MB-468 breast tumors that overexpress furin. We found that mice co-injected with 1 and 1-Cold show obviously higher uptake of radioactivity in tissues than those only injected with 1. During the 360 min microPET imaging of mice post injection, tumor uptake ratio between mice of these two groups gradually increased, reaching its maximum of 8.2 folds at 240 min.


Enzyme-Controlled Intracellular Self-Assembly of (18)F Nanoparticles for Enhanced MicroPET Imaging of Tumor.

Liu Y, Miao Q, Zou P, Liu L, Wang X, An L, Zhang X, Qian X, Luo S, Liang G - Theranostics (2015)

Shematic illustration of a furin-controlled condensation of 1 to assemble radioactive nanoparticles in cancer cells. After entering cancer cells, the disulfide bond of probe 1 is reduced by GSH and the RVRR peptide sequence is cleaved by furin to yield the active intermediate 1-Core. Two 1-Cores condense to yield amphiphilic dimers which self-assemble into 1-NPs at or near the locations of furin (i.e., Golgi bodies) in cancer cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4508496&req=5

SC1: Shematic illustration of a furin-controlled condensation of 1 to assemble radioactive nanoparticles in cancer cells. After entering cancer cells, the disulfide bond of probe 1 is reduced by GSH and the RVRR peptide sequence is cleaved by furin to yield the active intermediate 1-Core. Two 1-Cores condense to yield amphiphilic dimers which self-assemble into 1-NPs at or near the locations of furin (i.e., Golgi bodies) in cancer cells.
Mentions: Our design is illustrated in Scheme 1. Briefly, the SMB probe, Acetyl-Arg-Val-Arg-Arg-Cys(StBu)-Lys(18F-FB)-CBT (1), was designed to have these components as following: (1) a RVRR peptide sequence for cell-membrane-translocation and furin (a protease overexpressed in cancer) cleavage; (2) a disulfided Cys for supplying the 1,2-aminothiol group to condense with the cyano group on the 2-cyanobenzothiazole (CBT) motif; (3) a Lys whose side chain is covalently conjugated with 4-18F-fluorobenzoate (18F-FB) for positron emission tomography (PET) imaging. After entering cancer cells, the disulfide bond of the Cys motif of 1 is reduced by the intracellular glutathione (GSH) and subsequently its RVRR motif is cleaved by furin, resulting in the active intermediate 1-Core. Two 1-Cores quickly condense to yield the amphiphilic oligomers (e.g., dimer of 1-Core, 1-Dimer) which self-assemble into nanoparticles (i.e., 1-NPs) via π-π stacking among each other. As-formed 1-NPs could concentrate the radioactivity inside tumor cells, rendering enhanced PET imaging of tumors. Moreover, the big size and the hydrophobic nature of 1-NPs would prevent themselves from being pumped out by the cells, resulting in longer retention time in cells or longer circulation time in vivo, which is also good for tumor imaging. However, before approaching to furin at Golgi bodies, the cyano group of the radioactive probe 1 at very low chemical concentration (7.1 pmol kg-1 for PET imaging in this work) would condense with intracellular Cys, causing its self-condensation and assembly of 1-NPs infeasible. To resolve this, we have demonstrated that co-incubation of the radioactive probe (e.g., 1 herein) with its cold analog (e.g., 1-Cold herein Figure 1) above 25 µM would conquer intracellular Cys and warrant the self-assembly of the radioactive nanoparticles inside cells 44. In this paper, we designed 1-Cold for the co-injection with 1 into nude mice xenografted with MDA-MB-468 breast tumors that overexpress furin. We found that mice co-injected with 1 and 1-Cold show obviously higher uptake of radioactivity in tissues than those only injected with 1. During the 360 min microPET imaging of mice post injection, tumor uptake ratio between mice of these two groups gradually increased, reaching its maximum of 8.2 folds at 240 min.

Bottom Line: TEM images of 1-Cold-treated MDA-MB-468 cells directly uncovered that the intracellular 1-Cold-NPs were at/near the location of furin (i.e., Golgi bodies).MTT results indicated that 50 µM 1-Cold did not impose cytotoxicity to MDA-MB-468 cells up to 12 hours.Our ''smart'' probe (i.e., 1), together with the strategy of co-injection, might help researchers trace the biomarkers of interest within a longer time window.

View Article: PubMed Central - PubMed

Affiliation: 1. School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China ; 3. Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu 214063, China.

ABSTRACT
Herein, we report the development of a new "smart" radioactive probe (i.e., 1) which can undergo furin-controlled condensation and self-assembly of radioactive nanoparticles (i.e., 1-NPs) in tumor cells and its application for enhanced microPET imaging of tumors in nude mice co-injected with its cold analog (i.e., 1-Cold). Furin-controlled condensation of 1-Cold and self-assembly of its nanoparticles (i.e., 1-Cold-NPs) in vitro were validated and characterized with HPLC, mass spectra, SEM, and TEM analyses. Cell uptake studies showed that both 1 and 1-Cold have good cell permeability. TEM images of 1-Cold-treated MDA-MB-468 cells directly uncovered that the intracellular 1-Cold-NPs were at/near the location of furin (i.e., Golgi bodies). MTT results indicated that 50 µM 1-Cold did not impose cytotoxicity to MDA-MB-468 cells up to 12 hours. MicroPET imaging of MDA-MB-468 tumor-bearing mice indicated that mice co-injected with 1 and 1-Cold showed higher uptake and longer attenuation of the radioactivity in tumors than those mice only injected with same dosage of 1. Tumor uptake ratios of 1 between these two groups of mice reached the maximum of 8.2 folds at 240 min post injection. Biodistribution study indicated that the uptake ratios of 1 in kidneys between these two groups continuously increased and reached 81.9 folds at 240 min post injection, suggesting the formation of radioactive NPs (i.e., 1-NPs) in MDA-MB-468 tumors of mice co-injected with 1 and 1-Cold. And the nanoparticles were slowly digested and secreted from the tumors, accumulating in the kidneys. Our ''smart'' probe (i.e., 1), together with the strategy of co-injection, might help researchers trace the biomarkers of interest within a longer time window.

No MeSH data available.


Related in: MedlinePlus