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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

(a) Representative whole body coronal microPET images of mice with subcutaneously xenografted MDA-MB-468 tumors at different time points post intravenous injections of 85 µCi 1 (top) or 85 µCi 1 with 20 µmol/kg 1-Cold (bottom) via tail veins. Tumors are indicated by white arrows. (b) Time-course uptake of 1 in heart, liver, kidney, gall bladder, and MDA-MB-468 tumor derived from PET quantification (%ID/g, n = 4 for each group). Tissue radioactivity is expressed as the percentage of injected dose per gram of tissue (%ID/g). *: Not detectable.
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Figure 5: (a) Representative whole body coronal microPET images of mice with subcutaneously xenografted MDA-MB-468 tumors at different time points post intravenous injections of 85 µCi 1 (top) or 85 µCi 1 with 20 µmol/kg 1-Cold (bottom) via tail veins. Tumors are indicated by white arrows. (b) Time-course uptake of 1 in heart, liver, kidney, gall bladder, and MDA-MB-468 tumor derived from PET quantification (%ID/g, n = 4 for each group). Tissue radioactivity is expressed as the percentage of injected dose per gram of tissue (%ID/g). *: Not detectable.

Mentions: After validating overexpression of furin in MDA-MB-468 breast cancer cells by western blotting, our next plan was to use MDA-MB-468 tumor xenografts to demonstrate the furin-controlled intracellular self-assembly of 1-NPs in vivo for an enhanced microPET imaging of tumors in mice. As aforementioned, to ensure the feasibility of intracellular self-assembly of 1 into 1-NPs, co-injection of 1-Cold with 1 into mice to conquer intracellular Cys is a must. To characterize the concentration effect of 1-Cold on the self-assembly of 1-NPs, we did cellular efflux titration on MDA-MB-468 cells pre-incubated with 4 μCi of 1 and 1-Cold at 0, 5, 25, or 50 μM and 37 °C, respectively. The results indicated that 120 min after cell efflux, cells incubated with 1 alone have 13.1 ± 1.2% of initial radioactivity retained while those cells co-incubated with 5, 25, or 50 μM 1-Cold have 20.3 ± 4.2%, 28.5 ± 1.4%, or 32.1 ± 0.9% of initial radioactivity retained, respectively (Supplementary Material: Figure S16). Therefore, in this study, MDA-MB-468 tumor-bearing nude mice were each co-injected with 85 µCi of 1 and 20 µmol/kg 1-Cold via tail vein for microPET scans. Those tumor-bearing nude mice only injected with the same dosage of 1 were studied in parallel. Before microPET imaging, we conducted pharmacokinetic study of 1 in mice after intravenous (i.v.) administration at about 3.0 mCi/kg. The profiles of mean plasma concentration of 1 vs. time were best fitted to a two-compartment model (R2 = 0.957). The blood circulation half-time (t1/2) was estimated to be 86.1 min (t1/2α = 1.4 min, t1/2β = 84.7 min). The mean AUC0-t value was 452.2 min mCi L-1, CLtot was 0.006 L min-1 kg-1, Vd was 1.042 L kg-1, and Cmax was 7.471 mCi L-1, respectively (Supplementary Material: Figure S17). These data indicate that clearance of 1 in mouse is relatively slow. From the preliminary results of radiolabeling and pharmacokinetic study, we could calculate that the co-injection dose of 1-Cold (i.e., 20 µmol/kg) could result in Cmax of 49.8 µM of 1-Cold in blood, which is obviously higher than the concentration for self-assembling 1-NPs (i.e., 25 µM). The microPET imaging results are shown in Figure 5a. Coronal microPET imaging of mice showed that MDA-MB-468 tumors in the mice co-injected with 1 and 1-Cold were clearly visualized with good tumor-to-background contrast from 30 to 360 min (bottom panels of Figure 5a). Interestingly, tumors in those mice that only injected with 1 also could be visualized at 30 min and 60 min post injection but their PET images attenuated very fast after 60 min (top panels of Figure 5a). These results suggested that the radioactive probe 1 has a good tumor uptake enough for tumor PET imaging but co-injection of 1 with 1-Cold results in better uptake and longer attenuation of the radioactivity in tumor. Quantitative analysis of radioactivity values of tumor PET images showed that mice co-injected with 1 and 1-Cold had tumor uptake of radioactivity significantly higher than that of mice only injected with 1 at all time points studied (Supplementary Material: Table S4). At time points of 10, 30, 60, 120, 240, 360 min post injection, mice co-injected with 1 and 1-Cold had tumor uptake of 2.52 ± 0.95%, 4.08 ± 0.48%, 3.31 ± 1.22%, 2.27 ± 1.86%, 1.55 ± 1.75%, 1.28 ± 1.07% ID/g of 1, respectively. For mice only injected with 1, they had tumor uptake of 1.02 ± 0.19%, 1.12 ± 0.08%, 0.52 ± 0.18%, 0.28 ± 0.02%, 0.19 ± 0.03%, and 0.19 ± 0.05% ID/g of 1 at these time points respectively (Supplementary Material: Table S4). Quantitative results showed that tumor uptake ratios between these two groups of mice are 2.5 (at 10 min), 3.6 (at 30 min), 6.4 (at 60 min), 7.9 (at 120 min), 8.2 (at 240 min), 6.5 (at 360 min), respectively (Figure 5b, and Supplementary Material: Table S4). These results indicated that co-injection of 1 with 1-Cold is obviously better than 1 alone for microPET imaging of MDA-MB-468 tumors, suggesting that 1-Cold helps the furin-controlled intracellular condensation and self-assembly of 1 into 18F-NPs (i.e., 1-NPs) in tumors.


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)

(a) Representative whole body coronal microPET images of mice with subcutaneously xenografted MDA-MB-468 tumors at different time points post intravenous injections of 85 µCi 1 (top) or 85 µCi 1 with 20 µmol/kg 1-Cold (bottom) via tail veins. Tumors are indicated by white arrows. (b) Time-course uptake of 1 in heart, liver, kidney, gall bladder, and MDA-MB-468 tumor derived from PET quantification (%ID/g, n = 4 for each group). Tissue radioactivity is expressed as the percentage of injected dose per gram of tissue (%ID/g). *: Not detectable.
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Related In: Results  -  Collection

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Figure 5: (a) Representative whole body coronal microPET images of mice with subcutaneously xenografted MDA-MB-468 tumors at different time points post intravenous injections of 85 µCi 1 (top) or 85 µCi 1 with 20 µmol/kg 1-Cold (bottom) via tail veins. Tumors are indicated by white arrows. (b) Time-course uptake of 1 in heart, liver, kidney, gall bladder, and MDA-MB-468 tumor derived from PET quantification (%ID/g, n = 4 for each group). Tissue radioactivity is expressed as the percentage of injected dose per gram of tissue (%ID/g). *: Not detectable.
Mentions: After validating overexpression of furin in MDA-MB-468 breast cancer cells by western blotting, our next plan was to use MDA-MB-468 tumor xenografts to demonstrate the furin-controlled intracellular self-assembly of 1-NPs in vivo for an enhanced microPET imaging of tumors in mice. As aforementioned, to ensure the feasibility of intracellular self-assembly of 1 into 1-NPs, co-injection of 1-Cold with 1 into mice to conquer intracellular Cys is a must. To characterize the concentration effect of 1-Cold on the self-assembly of 1-NPs, we did cellular efflux titration on MDA-MB-468 cells pre-incubated with 4 μCi of 1 and 1-Cold at 0, 5, 25, or 50 μM and 37 °C, respectively. The results indicated that 120 min after cell efflux, cells incubated with 1 alone have 13.1 ± 1.2% of initial radioactivity retained while those cells co-incubated with 5, 25, or 50 μM 1-Cold have 20.3 ± 4.2%, 28.5 ± 1.4%, or 32.1 ± 0.9% of initial radioactivity retained, respectively (Supplementary Material: Figure S16). Therefore, in this study, MDA-MB-468 tumor-bearing nude mice were each co-injected with 85 µCi of 1 and 20 µmol/kg 1-Cold via tail vein for microPET scans. Those tumor-bearing nude mice only injected with the same dosage of 1 were studied in parallel. Before microPET imaging, we conducted pharmacokinetic study of 1 in mice after intravenous (i.v.) administration at about 3.0 mCi/kg. The profiles of mean plasma concentration of 1 vs. time were best fitted to a two-compartment model (R2 = 0.957). The blood circulation half-time (t1/2) was estimated to be 86.1 min (t1/2α = 1.4 min, t1/2β = 84.7 min). The mean AUC0-t value was 452.2 min mCi L-1, CLtot was 0.006 L min-1 kg-1, Vd was 1.042 L kg-1, and Cmax was 7.471 mCi L-1, respectively (Supplementary Material: Figure S17). These data indicate that clearance of 1 in mouse is relatively slow. From the preliminary results of radiolabeling and pharmacokinetic study, we could calculate that the co-injection dose of 1-Cold (i.e., 20 µmol/kg) could result in Cmax of 49.8 µM of 1-Cold in blood, which is obviously higher than the concentration for self-assembling 1-NPs (i.e., 25 µM). The microPET imaging results are shown in Figure 5a. Coronal microPET imaging of mice showed that MDA-MB-468 tumors in the mice co-injected with 1 and 1-Cold were clearly visualized with good tumor-to-background contrast from 30 to 360 min (bottom panels of Figure 5a). Interestingly, tumors in those mice that only injected with 1 also could be visualized at 30 min and 60 min post injection but their PET images attenuated very fast after 60 min (top panels of Figure 5a). These results suggested that the radioactive probe 1 has a good tumor uptake enough for tumor PET imaging but co-injection of 1 with 1-Cold results in better uptake and longer attenuation of the radioactivity in tumor. Quantitative analysis of radioactivity values of tumor PET images showed that mice co-injected with 1 and 1-Cold had tumor uptake of radioactivity significantly higher than that of mice only injected with 1 at all time points studied (Supplementary Material: Table S4). At time points of 10, 30, 60, 120, 240, 360 min post injection, mice co-injected with 1 and 1-Cold had tumor uptake of 2.52 ± 0.95%, 4.08 ± 0.48%, 3.31 ± 1.22%, 2.27 ± 1.86%, 1.55 ± 1.75%, 1.28 ± 1.07% ID/g of 1, respectively. For mice only injected with 1, they had tumor uptake of 1.02 ± 0.19%, 1.12 ± 0.08%, 0.52 ± 0.18%, 0.28 ± 0.02%, 0.19 ± 0.03%, and 0.19 ± 0.05% ID/g of 1 at these time points respectively (Supplementary Material: Table S4). Quantitative results showed that tumor uptake ratios between these two groups of mice are 2.5 (at 10 min), 3.6 (at 30 min), 6.4 (at 60 min), 7.9 (at 120 min), 8.2 (at 240 min), 6.5 (at 360 min), respectively (Figure 5b, and Supplementary Material: Table S4). These results indicated that co-injection of 1 with 1-Cold is obviously better than 1 alone for microPET imaging of MDA-MB-468 tumors, suggesting that 1-Cold helps the furin-controlled intracellular condensation and self-assembly of 1 into 18F-NPs (i.e., 1-NPs) in tumors.

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