HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JNM Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chan, C. Articles by Reilly, R. M. Search for Related Content PubMed PubMed Citation Articles by Chan, C. Articles by Reilly, R. M.

A Human Transferrin-Vascular Endothelial Growth Factor (hnTf-VEGF) Fusion Protein Containing an Integrated Binding Site for ¹¹¹In for Imaging Tumor Angiogenesis

¹ Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
² Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, Toronto, Ontario, Canada
³ Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
⁴ Transplant Research Division, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
⁵ Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
⁶ Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada

Our objective was to synthesize a recombinant protein (hnTf-VEGF [VEGF is vascular endothelial growth factor]) composed of VEGF₁₆₅ fused through a flexible polypeptide linker (GGGGS)₃ to the n-lobe of human transferrin (hnTf) for imaging angiogenesis. The hnTf domain allowed labeling with ¹¹¹In at a site remote from the VEGF receptor-binding domain. Methods: DNA encoding hnTf, peptide linker (GGGGS)₃, and VEGF₁₆₅ genes were cloned into the Pichia pastoris vector pPICZB to generate the pPICZB-hnTF-VEGF plasmid. The expression vector was transformed into P. pastoris KM71H strain. The protein was purified using Co²⁺ metal affinity resin. The growth-stimulatory effects of hnTf-VEGF on human umbilical vascular endothelial cells (HUVECs) and its binding to porcine aortic endothelial cells (PAECs) transfected with VEGF receptors were evaluated. hnTf-VEGF protein was labeled with ¹¹¹InCl₃ in 10 mmol/L HEPES/15 mmol/L NaHCO₃ buffer, pH 7.4 (HEPES is N-(2-hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid). The loss of ¹¹¹In in vitro from ¹¹¹In-hnTf-VEGF to transferrin in human plasma and to diethylenetriaminepentaacetic acid (DTPA) in buffer was determined. Tumor and normal tissue distributions of ¹¹¹In-hnTf-VEGF were evaluated in athymic mice implanted subcutaneously with U87MG human glioblastoma xenografts. Tumor imaging was performed. Results: Sodium dodecylsulfate–polyacrylamine gel electrophoresis under reducing and nonreducing conditions showed bands for hnTf-VEGF monomer (M_r of 65 kDa) and dimer (M_r of 130 kDa). hnTf-VEGF stimulated the growth of HUVECs 3-fold and demonstrated binding to PAECs displaced by a 50-fold excess of VEGF₁₆₅ but not by apotransferrin. There was 21.3% ± 3.4% loss of ¹¹¹In per day from ¹¹¹In-hnTf-VEGF to transferrin in plasma, but <5% loss to DTPA over 4 h. ¹¹¹In-hnTf-VEGF accumulated in U87MG tumors (6.7% injected dose per gram at 72 h after injection) and its tumor uptake decreased 15-fold by coadministration of a 100-fold excess of VEGF but not by apotransferrin. The tumor-to-blood ratio was 4.9:1 at 72 h after injection and tumors were imaged at 24–72 h after injection. Conclusion: ¹¹¹In-hnTf-VEGF is a promising radiopharmaceutical for imaging tumor angiogenesis and represents a prototypic protein harboring the metal-binding site of transferrin for labeling with ¹¹¹In without introducing DTPA metal chelators.

Key Words: vascular endothelial growth factor • transferrin • angiogenesis • ¹¹¹In • glioblastomas

Related articles in JNM:

THIS MONTH IN JNM

JNM 2005 46: 8a-9a. [Full Text]  

This article has been cited by other articles:

				W. Cai and X. Chen Multimodality Molecular Imaging of Tumor Angiogenesis J. Nucl. Med., June 1, 2008; 49(Suppl_2): 113S - 128S. [Abstract] [Full Text] [PDF]

				A. R. Hsu, W. Cai, A. Veeravagu, K. A. Mohamedali, K. Chen, S. Kim, H. Vogel, L. C. Hou, V. Tse, M. G. Rosenblum, et al. Multimodality Molecular Imaging of Glioblastoma Growth Inhibition with Vasculature-Targeting Fusion Toxin VEGF121/rGel J. Nucl. Med., March 1, 2007; 48(3): 445 - 454. [Abstract] [Full Text] [PDF]

				W. Cai, K. Chen, K. A. Mohamedali, Q. Cao, S. S. Gambhir, M. G. Rosenblum, and X. Chen PET of Vascular Endothelial Growth Factor Receptor Expression J. Nucl. Med., December 1, 2006; 47(12): 2048 - 2056. [Abstract] [Full Text] [PDF]

				W. Cai, J. Rao, S. S. Gambhir, and X. Chen How molecular imaging is speeding up antiangiogenic drug development. Mol. Cancer Ther., November 1, 2006; 5(11): 2624 - 2633. [Abstract] [Full Text] [PDF]

				S. K. Libutti Assessing Antiangiogenic Therapy in Preclinical Models and Clinical Trials Using Noninvasive Imaging Techniques Am. Assoc. Cancer Res. Educ. Book, April 1, 2006; 2006(1): 191 - 194. [Full Text] [PDF]