Title:Human Fibronectin Extra-Domain B (EDB)-Specific Aptide (APTEDB) Radiolabelling with Technetium-99m as a Potent Targeted Tumour-Imaging Agent
VOLUME: 18 ISSUE: 2
Author(s):Mohsen Mohammadgholi, Nourollah Sadeghzadeh*, Mostafa Erfani, Saeid Abediankenari, Seyed Mohammad Abedi, Iman Emrarian, Narjes Jafari and Ramezan Behzadi
Affiliation:Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran (AEOI), Tehran, Immunogenetics Research Centre, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Department of Radiology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Immunogenetics Research Centre, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, North Research Centre-Pasteur Institute of Iran, Amol
Keywords:Aptide, fibronectin extra-domain B, HYNIC, phage display, radiolabelling, technetium-99m, tumour imaging agent, APTEDB.
Abstract:Background: Human fibronectin extra-domain B (EDB) is particularly expressed during angiogenesis
progression. It is, thus, a promising marker of tumour growth. Aptides are a novel class of peptides with
high-affinity binding to specific protein targets. APTEDB is an antagonist-like ligand that especially interacts with
human fibronectin EDB.
Objective: This study was the first attempt in which the hydrazinonicotinamide (HYNIC)-conjugated APTEDB
was labelled with technetium-99m (99mTc) as an appropriate radiotracer and tricine/EDDA exchange labeling.
Methods: Radiochemical purity, normal saline, and serum stability were evaluated by HPLC and radio-isotope
TLC scanner. Other examinations, such as protein-binding calculation, dissociation radioligand binding assay,
and partition coefficient constant determination, were also carried out. The cellular-specific binding of 99mTc-
HYNIC-conjugated APTEDB was assessed in two EDB-positive (U87MG) and EDB-negative (U373MG) cell
lines. Bio-distribution was investigated in normal mice as well as in U87MG and U373MG tumour-bearing
mice. Eventually, the radiolabelled APTEDB was used for tumour imaging using planar SPECT.
Results: Radiolabelling was achieved with high purity (up to 97%) and accompanied by high solution (over
90% after overnight) and serum (80% after 2 hours) stability. The obtained cellular-specific binding ratio was
greater than nine-fold. In-vivo experiments showed rapid blood clearance with mainly renal excretion and tumour
uptake specificity (0.48±0.03% ID/g after 1h). The results of the imaging also confirmed considerable
tumour uptake for EDB-positive cell line compared with the EDB-negative one.
Conclusion: Aptides are considered to be a potent candidate for biopharmaceutical applications. They can be
modified with imaging or therapeutic agents. This report shows the capability of 99mTc-HYNIC-APTEDB for
human EDB-expressing tumours detection.
