• Biological Effects Evaluation of PEG-BBN Peptide Labeled with Indium-113m Radionuclide on Cancer Cells Expressing (GRP) receptor
  • Fatemeh Badipa,1 Safar Farajnia,2 Farahnaz Motamedi Sedeh,3 Behrouz Alirezapuor,4,*
    1. Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
    2. Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
    3. Nuclear Science and Technology Research Institute, Karaj, Iran
    4. Radiation Application Research School, Nuclear Science and Technology Research Institute, Tehran, ‎Iran


  • Introduction: One of the well-known receptors that is overexpressed in human prostate cancer (PC) is the Bombesin Receptor (BBN), an analog of gastrin-releasing peptide (GRP) that binds tightly to the GRP receptor. Gastrin-releasing peptide receptors (GRPRs) are attractive targets for molecular imaging, as they are overexpressed in human PC. Bombesin (BBN)-based peptides exhibit a high binding affinity to GRPRs and could be utilized as specific tumor-targeting ligands. The aim of this investigation is to optimize the radiolabeling of peptides with the Indium-113m radionuclide and produce suitable radiopharmaceuticals for imaging studies of prostate cancer.
  • Methods: For the In113m labeling, Briefly, 5 nmol of PEG-BBN peptide was dissolved in 500 μL of 0.1 M sodium acetate buffer and incubated with 4 mCi (148 MBq) of In113m for 15 min at 95°C. In 113 m –analytical HPLC then purified PEG-BBN product, and the radioactive peak containing the desired product was collected. After removal of the solvent by rotary evaporation, the activity was then reconstituted in PBS and passed through a 0.22-μm Millipore filter into a sterile multidose vial for in vitro and in vivo experiments. The Biodistribution study was performed on the normal mice (25-30 g). The bioconjugations were injected via the tail vein for each mouse. The amount of bioconjugations that were injected into each mouse was 50 mci of (In113m –PEG-BBN) in a volume of 100 µl. The mice were sacrificed at 15, 30, 60, and 90 minutes post-injection (four mice per time point). Sacrificed mice were first imaged and then dissected. The blood was collected by cardiac puncture, and the liver, heart, intestines, kidneys, urine, stomach, pancreas, muscle, lungs, skin, and tissues were dissected and weighed. The uptake of each tissue was measured using a gamma counter. The uptake of (In113m –PEG-BBN) conjugate in each organ was calculated as the mean percentage of injected dose per gram of organ tissues (%ID/g).
  • Results: The percentage of radiochemical purity was 100%, with a radiolabeling yield of 100%. Biodistribution study was performed in normal Balb/c mice at time intervals (15, 30, 60, and 120) minutes after the injection, expressed as percentage of injected dose per gram of tissue (%ID/g), biodistribution study and imaging study of free 113mIn and 113mIn –PEG-BBN showed similar accumulation pattern and had the highest absorption in blood and kidney within 15 minutes after injection, and with the passage of time its absorption in kidney, liver and bone increased.
  • Conclusion: 113mIn –PEG-BBN is a potential compound for SPECT imaging of the prostate cancer cells.
  • Keywords: Prostate cancer, Gastrin-releasing peptide (GRP), 113mIn –PEG-BBN