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Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2013.

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Molecular Imaging and Contrast Agent Database (MICAD) [Internet].

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64Cu-1,4,7,10-Tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-Asp-cyclohexylalanine-Phe-d-Ser-d-Arg-Tyr-Leu-Trp-Ser-NH2 (AE105-NH2)

64Cu-DOTA-AE105-NH2
, PhD
National Center for Biotechnology Information, NLM, NIH

Created: ; Last Update: August 23, 2012.

Chemical name:64Cu-1,4,7,10-Tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-Asp-cyclohexylalanine-Phe-d-Ser-d-Arg-Tyr-Leu-Trp-Ser-NH2 (AE105-NH2)
Abbreviated name:64Cu-DOTA-AE105-NH2, 64Cu-DOTA-d-Cha-F-s-r-Y-L-W-S-NH2
Synonym:
Agent category:Peptide
Target:Urokinase-type plasminogen activator receptor (uPAR)
Target category:Receptor
Method of detection:Positron emission tomography (PET)
Source of signal:64Cu
Activation:No
Studies:
  • Checkbox In vitro
  • Checkbox Rodents
Click on protein, nucleotide (RefSeq), and gene for more information about uPAR.

Background

[PubMed]

Extracellular matrix (ECM) adhesion molecules consist of a complex network of fibronectins, collagens, chondroitins, laminins, glycoproteins, heparin sulfate, tenascins, and proteoglycans that surround connective tissue cells, and they are mainly secreted by fibroblasts, chondroblasts, and osteoblasts (1). Cell substrate adhesion molecules are considered essential regulators of cell migration, differentiation, and tissue integrity and remodeling. These molecules play an important role in inflammation and atherogenesis, but they also participate in the process of invasion and metastasis of malignant cells in the host tissue (2). Invasive tumor cells adhere to the ECM, which provides a matrix environment for permeation of tumor cells through the basal lamina and underlying interstitial stroma of the connective tissue. Overexpression of matrix metalloproteinases (MMPs) and other proteases by tumor cells allows intravasation of tumor cells into the circulatory system after degradation of the basement membrane and ECM (3). Several families of proteases are involved in atherogenesis, myocardial infarction, angiogenesis, and tumor invasion and metastasis (4-7).

Urokinase-type plasminogen activator (uPA) is a serine protease (8, 9). The uPA/uPA receptor (uPAR) system is responsible for tissue degradation after plasminogen activation to plasmin, which leads to a cascade of proteolysis or thrombolysis, depending on the physiological conditions. uPA also directly activates MMPs, vascular endothelial growth factor, and human growth factor (10). Malignant tumors often express high levels of uPA and uPAR (11); therefore, the uPA/uPAR system is linked to vascular diseases and cancer. The synthetic peptide Asp-cyclohexylalanine-Phe-d-Ser-d-Arg-Tyr-Leu-Trp-Ser (AE105) has been identified to have a high affinity (dissociation constant for human uPAR (Kd) = 0.4 nM) (12), and AE105 has been labeled with 64Cu (T1/2 = 12.7 h, β+ = 17.8%) as 64Cu-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-AE105 (64Cu-DOTA-AE105) for use in positron emission tomography (PET) imaging of uPAR expression in tumors (13). Persson et al. (14) extended the evaluation of AE105 in PET and biodistribution studies with 64Cu-DOTA-AE105-NH2.

Related Resource Links

  • Chapters in MICAD (uPAR)
  • Gene information in NCBI (uPAR, uPA)
  • Articles in Online Mendelian Inheritance in Man (OMIM) (uPAR, uPA)

Synthesis

[PubMed]

Persson et al. (14) performed DOTA chelation of the N-terminus of AE105-NH2via solid-phase synthesis. A mixture of AE105-NH2 and DOTA-tris(tBu)ester in a molar ratio of 1:3 was incubated for 24–48 h at room temperature. The DOTA-AE105-NH2 conjugate was purified with high-performance liquid chromatography (HPLC). The number of DOTA molecules per peptide was ~1 as determined with mass spectroscopy. For radiolabeling, DOTA-AE105-NH2 (2 nmol) was added to 150 MBq (4 mCi) 64CuCl2 diluted in 0.1 M ammonium acetate buffer (pH 8.0). The reaction mixture was incubated for 1 h at 70ºC with a radiolabeling yield of >90%. 64Cu-DOTA-AE105-NH2 was purified with a Sep-Pak cartridge (>95% radiochemical purity). 64Cu-DOTA-AE105mut-NH2, used as an inactive control, was prepared similarly. The specific activities of 64Cu-DOTA-AE105 and 64Cu-DOTA-AE105mut-NH2 were ~25 GBq/μmol (0.68 Ci/μmol) at the end of synthesis.

In Vitro Studies: Testing in Cells and Tissues

[PubMed]

Persson et al. (14) performed binding experiments with AE105-NH2, DOTA-AE105-NH2, and inactive DOTA-AE105mut-NH2 with the use of a Biacore sensor chip immobilized with pro-uPA. The IC50 values for inhibiting the binding of uPAR (0.5 nM) to pro-uPA were 7.6 ± 2.0 nM, 6.7 ± 0.9 nM, and >10 µM for AE105-NH2, DOTA-AE105-NH2, and inactive DOTA-AE105mut-NH2, respectively.

Animal Studies

Rodents

[PubMed]

Persson et al. (14) performed ex vivo biodistribution studies at 4.5 h after injection of 64Cu-DOTA-AE105-NH2 or 64Cu-DOTA-AE105mut-NH2 in mice (n = 3/group) bearing U87MG human glioblastomas (uPAR-positive). The accumulation levels of 64Cu-DOTA-AE105-NH2 and 64Cu-DOTA-AE105mut-NH2 in the U87MG tumors were 4.2 ± 0.8% injected dose per gram (ID/g) and 1.2 ± 0.1% ID/g, respectively. The accumulation of both tracers was similar in the normal organs, with the highest accumulation of radioactivity in the liver (11%–14% ID/g) and kidneys (~6% ID/g). The tumor/blood and tumor/muscle ratios for 64Cu-DOTA-AE105-NH2 were 3.5 and 14.0, respectively. The tumor/blood and tumor/muscle ratios for 64Cu-DOTA-AE105mut-NH2 were 1.2 and 4.3, respectively.

PET imaging studies were performed at 1, 4.5, and 22 h after injection of 64Cu-DOTA-AE105-NH2 or 64Cu-DOTA-AE105mut-NH2 in mice bearing U87MG tumors (n = 3/group) (14). The tumors were clearly visualized for 64Cu-DOTA-AE105-NH2 at all three time points, with 5%–6% ID/g. 64Cu-DOTA-AE105-NH2 exhibited a significantly higher (P < 0.001) tumor accumulation than 64Cu-DOTA-AE105mut-NH2 (1.6%–2.2% ID/g). Pretreatment (5 min) with 2 nmol DOTA-AE105-NH2 before 64Cu-DOTA-AE105-NH2 injection inhibited the tumor accumulation by 78% at 4.5 h after injection (P < 0.001).

Persson et al. (14) performed 64Cu-DOTA-AE105-NH2 PET imaging in mice (n = 4/group) bearing H727 (low uPAR expression), HT-29 (moderate uPAR expression), or U87Mg (high uPAR expression) xenografts at 1, 4.5, and 22 h after injection. There was a significant correlation (R2 = 0.73; P < 0.001) between tumor accumulation and uPAR expression at these time points. In another experiment, the tumor accumulation of [18F]FDG and 64Cu-DOTA-AE105-NH2 was compared in mice bearing H727 and U87MG tumors at 1 h after injection. The tumor accumulation of FDG was similar in H727 (1.52 ± 0.03% ID/g) and U87MG (1.97 ± 0.18% ID/g) tumors, whereas the tumor accumulation of 64Cu-DOTA-AE105-NH2 was significantly (P < 0.05) higher in U87MG (3.88 ± 0.74% ID/g) than in H727 tumors (1.71 ± 0.11% ID/g).

Other Non-Primate Mammals

[PubMed]

No publication is currently available.

Non-Human Primates

[PubMed]

No publication is currently available.

Human Studies

[PubMed]

No publication is currently available.

References

1.
Bosman F.T., Stamenkovic I. Functional structure and composition of the extracellular matrix. J Pathol. 2003;200(4):423–8. [PubMed: 12845610]
2.
Jiang W.G., Puntis M.C., Hallett M.B. Molecular and cellular basis of cancer invasion and metastasis: implications for treatment. Br J Surg. 1994;81(11):1576–90. [PubMed: 7827878]
3.
Albelda S.M. Role of integrins and other cell adhesion molecules in tumor progression and metastasis. Lab Invest. 1993;68(1):4–17. [PubMed: 8423675]
4.
Keppler D., Sameni M., Moin K., Mikkelsen T., Diglio C.A., Sloane B.F. Tumor progression and angiogenesis: cathepsin B & Co. Biochem Cell Biol. 1996;74(6):799–810. [PubMed: 9164649]
5.
Liu J., Sukhova G.K., Sun J.S., Xu W.H., Libby P., Shi G.P. Lysosomal cysteine proteases in atherosclerosis. Arterioscler Thromb Vasc Biol. 2004;24(8):1359–66. [PubMed: 15178558]
6.
Berchem G., Glondu M., Gleizes M., Brouillet J.P., Vignon F., Garcia M., Liaudet-Coopman E. Cathepsin-D affects multiple tumor progression steps in vivo: proliferation, angiogenesis and apoptosis. Oncogene. 2002;21(38):5951–5. [PubMed: 12185597]
7.
Brix, K., A. Dunkhorst, K. Mayer, and S. Jordans, Cysteine cathepsins: Cellular roadmap to different functions. Biochimie, 2007. [PubMed: 17825974]
8.
Choong P.F., Nadesapillai A.P. Urokinase plasminogen activator system: a multifunctional role in tumor progression and metastasis. Clin Orthop Relat Res. 2003;(415) Suppl:S46–58. [PubMed: 14600592]
9.
Rabbani S.A., Mazar A.P. The role of the plasminogen activation system in angiogenesis and metastasis. Surg Oncol Clin N Am. 2001;10(2):393–415. [PubMed: 11382594]
10.
Folkman J., Shing Y. Angiogenesis. J Biol Chem. 1992;267(16):10931–4. [PubMed: 1375931]
11.
Duffy M.J., Maguire T.M., McDermott E.W., O'Higgins N. Urokinase plasminogen activator: a prognostic marker in multiple types of cancer. J Surg Oncol. 1999;71(2):130–5. [PubMed: 10389872]
12.
Ploug M., Ostergaard S., Gardsvoll H., Kovalski K., Holst-Hansen C., Holm A., Ossowski L., Dano K. Peptide-derived antagonists of the urokinase receptor. affinity maturation by combinatorial chemistry, identification of functional epitopes, and inhibitory effect on cancer cell intravasation. Biochemistry. 2001;40(40):12157–68. [PubMed: 11580291]
13.
Li Z.B., Niu G., Wang H., He L., Yang L., Ploug M., Chen X. Imaging of urokinase-type plasminogen activator receptor expression using a 64Cu-labeled linear peptide antagonist by microPET. Clin Cancer Res. 2008;14(15):4758–66. [PubMed: 18676745]
14.
Persson M., Madsen J., Ostergaard S., Jensen M.M., Jorgensen J.T., Juhl K., Lehmann C., Ploug M., Kjaer A. Quantitative PET of human urokinase-type plasminogen activator receptor with 64Cu-DOTA-AE105: implications for visualizing cancer invasion. J Nucl Med. 2012;53(1):138–45. [PubMed: 22213823]
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