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Hybrid PET/optical imaging of integrin αVβ3 receptor expression using a (64)Cu-labeled streptavidin/biotin-based dimeric RGD peptide.

Kang CM, Koo HJ, An GI, Choe YS, Choi JY, Lee KH, Kim BT - EJNMMI Res (2015)

Bottom Line: Receptor binding studies of DOTA-(AF)SAv/biotin-PEG-RGD2 were performed using U87MG cells and (125)I-RGDyK as the radioligand, and cellular uptake studies of (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 were also performed.Ex vivo PET/optical imaging and biodistribution studies of the major tissues were performed after the in vivo imaging, and immunofluorescence staining of the tumor tissue sections was carried out. (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 was prepared in 52.1 ± 5.4 % radiochemical yield and with specific activity of 1.0 ± 0.1 GBq/mg.Receptor binding studies showed that DOTA-(AF)SAv/biotin-PEG-RGD2 had higher binding affinity for integrin αVβ3 than RGD2, reflecting a possible polyvalency effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06351, Korea.

ABSTRACT

Background: Hybrid PET/optical imaging provides quantitative and complementary information for diagnosis of tumors. Herein, we developed a (64)Cu-labeled AlexaFluor 680-streptavidin ((AF)SAv)/biotin-based dimeric cyclic RGD peptide (RGD2) for hybrid PET/optical imaging of integrin αVβ3 expression.

Methods: (64)Cu-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-(AF)SAv/biotin-PEG-RGD2 was prepared by formation of a complex comprising DOTA-(AF)SAv and biotin-PEG-RGD2, followed by radiolabeling with (64)Cu. Receptor binding studies of DOTA-(AF)SAv/biotin-PEG-RGD2 were performed using U87MG cells and (125)I-RGDyK as the radioligand, and cellular uptake studies of (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 were also performed. MicroPET imaging followed by optical imaging of U87MG tumor-bearing mice was acquired after injection of the hybrid probe, and region of interest (ROI) analysis of tumors was performed. Ex vivo PET/optical imaging and biodistribution studies of the major tissues were performed after the in vivo imaging, and immunofluorescence staining of the tumor tissue sections was carried out.

Results: (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 was prepared in 52.1 ± 5.4 % radiochemical yield and with specific activity of 1.0 ± 0.1 GBq/mg. Receptor binding studies showed that DOTA-(AF)SAv/biotin-PEG-RGD2 had higher binding affinity for integrin αVβ3 than RGD2, reflecting a possible polyvalency effect. Moreover, the hybrid probe revealed time-dependent uptake by U87MG cells. In a microPET/optical imaging study, the hybrid probe demonstrated high accumulation in tumors; ROI analysis revealed 2.7 ± 0.2 % ID/g at 1 h and 4.7 ± 0.2 % ID/g at 21 h after injection, and subsequently acquired optical images showed tumors with strong fluorescence intensity. Ex vivo PET/optical images of the major tissues confirmed the in vivo imaging data, and biodistribution studies demonstrated high and specific uptake in tumors (4.8 ± 0.1 % ID/g). Immunofluorescence staining showed the formation of new blood vessels in tumor tissues, suggesting that the tumor uptake was due to specific binding of the hybrid probe to integrin αVβ3 expressed on tumor cells.

Conclusions: These results indicate that a (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 is able to provide quantitative information on hybrid PET/optical imaging of integrin αVβ3 expression.

No MeSH data available.


Related in: MedlinePlus

a MicroPET images of the 64Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 in U87MG tumor-bearing mice at 1, 2, 16, and 21 h after injection and (b) after co-injection with RGD2 (20 mg/kg). c Optical images at the same time points and (d) after co-injection with RGD2 (20 mg/kg). Arrows indicate tumors. e ROI analysis of radioactivity uptake in tumors obtained from microPET images (a, b): control (black) and blocking (white) groups. f ROI analysis of fluorescence intensity in tumors obtained from optical images (c, d): control (black) and blocking (white) groups. Values represent mean % ID/g and error bars indicate SD (n = 3). **P < 0.01, ***P < 0.001
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Fig5: a MicroPET images of the 64Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 in U87MG tumor-bearing mice at 1, 2, 16, and 21 h after injection and (b) after co-injection with RGD2 (20 mg/kg). c Optical images at the same time points and (d) after co-injection with RGD2 (20 mg/kg). Arrows indicate tumors. e ROI analysis of radioactivity uptake in tumors obtained from microPET images (a, b): control (black) and blocking (white) groups. f ROI analysis of fluorescence intensity in tumors obtained from optical images (c, d): control (black) and blocking (white) groups. Values represent mean % ID/g and error bars indicate SD (n = 3). **P < 0.01, ***P < 0.001

Mentions: In vivo microPET and optical imaging of U87MG tumor-bearing mice showed high uptake of the 64Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 in the liver, spleen, and tumor (Fig. 5a). ROI values of tumor tissues were 2.7 ± 0.2 % ID/g at 1 h, 2.8 ± 0.2 % ID/g at 2 h, 4.4 ± 0.2 % ID/g at 16 h, and 4.7 ± 0.2 % ID/g at 21 h (Fig. 5e). In the blocking study, tumor uptake was inhibited by 30.3 % in the presence of RGD2 (20 mg/kg) at 16 h after injection (Fig. 5b, e). In optical images, strong fluorescence signals were detected in the liver and tumor, which was a similar uptake pattern to that observed in the PET images (Fig. 5c, d). ROI values of tumor tissues revealed fluorescence signals of (3.7 ± 0.2) × 108 photons/s/cm2/sr at 1 h, (3.9 ± 0.3) × 108 photons/s/cm2/sr at 2 h, (6.0 ± 0.2) × 108 photons/s/cm2/sr at 16 h, and (6.7 ± 0.3) × 108 photons/s/cm2/sr at 21 h. In the presence of RGD2, signal intensity decreased to 4.9 ± 0.2 × 108 photons/s/cm2/sr at 21 h (Fig. 5f).Fig. 5


Hybrid PET/optical imaging of integrin αVβ3 receptor expression using a (64)Cu-labeled streptavidin/biotin-based dimeric RGD peptide.

Kang CM, Koo HJ, An GI, Choe YS, Choi JY, Lee KH, Kim BT - EJNMMI Res (2015)

a MicroPET images of the 64Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 in U87MG tumor-bearing mice at 1, 2, 16, and 21 h after injection and (b) after co-injection with RGD2 (20 mg/kg). c Optical images at the same time points and (d) after co-injection with RGD2 (20 mg/kg). Arrows indicate tumors. e ROI analysis of radioactivity uptake in tumors obtained from microPET images (a, b): control (black) and blocking (white) groups. f ROI analysis of fluorescence intensity in tumors obtained from optical images (c, d): control (black) and blocking (white) groups. Values represent mean % ID/g and error bars indicate SD (n = 3). **P < 0.01, ***P < 0.001
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Fig5: a MicroPET images of the 64Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 in U87MG tumor-bearing mice at 1, 2, 16, and 21 h after injection and (b) after co-injection with RGD2 (20 mg/kg). c Optical images at the same time points and (d) after co-injection with RGD2 (20 mg/kg). Arrows indicate tumors. e ROI analysis of radioactivity uptake in tumors obtained from microPET images (a, b): control (black) and blocking (white) groups. f ROI analysis of fluorescence intensity in tumors obtained from optical images (c, d): control (black) and blocking (white) groups. Values represent mean % ID/g and error bars indicate SD (n = 3). **P < 0.01, ***P < 0.001
Mentions: In vivo microPET and optical imaging of U87MG tumor-bearing mice showed high uptake of the 64Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 in the liver, spleen, and tumor (Fig. 5a). ROI values of tumor tissues were 2.7 ± 0.2 % ID/g at 1 h, 2.8 ± 0.2 % ID/g at 2 h, 4.4 ± 0.2 % ID/g at 16 h, and 4.7 ± 0.2 % ID/g at 21 h (Fig. 5e). In the blocking study, tumor uptake was inhibited by 30.3 % in the presence of RGD2 (20 mg/kg) at 16 h after injection (Fig. 5b, e). In optical images, strong fluorescence signals were detected in the liver and tumor, which was a similar uptake pattern to that observed in the PET images (Fig. 5c, d). ROI values of tumor tissues revealed fluorescence signals of (3.7 ± 0.2) × 108 photons/s/cm2/sr at 1 h, (3.9 ± 0.3) × 108 photons/s/cm2/sr at 2 h, (6.0 ± 0.2) × 108 photons/s/cm2/sr at 16 h, and (6.7 ± 0.3) × 108 photons/s/cm2/sr at 21 h. In the presence of RGD2, signal intensity decreased to 4.9 ± 0.2 × 108 photons/s/cm2/sr at 21 h (Fig. 5f).Fig. 5

Bottom Line: Receptor binding studies of DOTA-(AF)SAv/biotin-PEG-RGD2 were performed using U87MG cells and (125)I-RGDyK as the radioligand, and cellular uptake studies of (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 were also performed.Ex vivo PET/optical imaging and biodistribution studies of the major tissues were performed after the in vivo imaging, and immunofluorescence staining of the tumor tissue sections was carried out. (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 was prepared in 52.1 ± 5.4 % radiochemical yield and with specific activity of 1.0 ± 0.1 GBq/mg.Receptor binding studies showed that DOTA-(AF)SAv/biotin-PEG-RGD2 had higher binding affinity for integrin αVβ3 than RGD2, reflecting a possible polyvalency effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06351, Korea.

ABSTRACT

Background: Hybrid PET/optical imaging provides quantitative and complementary information for diagnosis of tumors. Herein, we developed a (64)Cu-labeled AlexaFluor 680-streptavidin ((AF)SAv)/biotin-based dimeric cyclic RGD peptide (RGD2) for hybrid PET/optical imaging of integrin αVβ3 expression.

Methods: (64)Cu-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-(AF)SAv/biotin-PEG-RGD2 was prepared by formation of a complex comprising DOTA-(AF)SAv and biotin-PEG-RGD2, followed by radiolabeling with (64)Cu. Receptor binding studies of DOTA-(AF)SAv/biotin-PEG-RGD2 were performed using U87MG cells and (125)I-RGDyK as the radioligand, and cellular uptake studies of (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 were also performed. MicroPET imaging followed by optical imaging of U87MG tumor-bearing mice was acquired after injection of the hybrid probe, and region of interest (ROI) analysis of tumors was performed. Ex vivo PET/optical imaging and biodistribution studies of the major tissues were performed after the in vivo imaging, and immunofluorescence staining of the tumor tissue sections was carried out.

Results: (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 was prepared in 52.1 ± 5.4 % radiochemical yield and with specific activity of 1.0 ± 0.1 GBq/mg. Receptor binding studies showed that DOTA-(AF)SAv/biotin-PEG-RGD2 had higher binding affinity for integrin αVβ3 than RGD2, reflecting a possible polyvalency effect. Moreover, the hybrid probe revealed time-dependent uptake by U87MG cells. In a microPET/optical imaging study, the hybrid probe demonstrated high accumulation in tumors; ROI analysis revealed 2.7 ± 0.2 % ID/g at 1 h and 4.7 ± 0.2 % ID/g at 21 h after injection, and subsequently acquired optical images showed tumors with strong fluorescence intensity. Ex vivo PET/optical images of the major tissues confirmed the in vivo imaging data, and biodistribution studies demonstrated high and specific uptake in tumors (4.8 ± 0.1 % ID/g). Immunofluorescence staining showed the formation of new blood vessels in tumor tissues, suggesting that the tumor uptake was due to specific binding of the hybrid probe to integrin αVβ3 expressed on tumor cells.

Conclusions: These results indicate that a (64)Cu-DOTA-(AF)SAv/biotin-PEG-RGD2 is able to provide quantitative information on hybrid PET/optical imaging of integrin αVβ3 expression.

No MeSH data available.


Related in: MedlinePlus