Evaluation of a new bombesin analogue labeled with 99mTc as potential targeted tumor scintigraphic agent

Background and aim: bombesin shows high affinity for gastrin-releasingpeptide (grp) receptors which over expressed on the cell surfaces of severalhuman tumors particularly in prostate and breast cancers. the aim of this studywas labeling of designed analogue with99mtc via hynic and tricine /edda andevaluation as potential targeted tumor scintigraphic agent.methods: hynic-bombesin was prepared by solid phase synthesis using fmocstrategy and radiolabeled with 99mtc at 100 °c for 10 min by exchange methodand radiochemical analysis involved itlc and hplc methods. the stability ofradiopeptide was checked in the presence of human serum at 37 °c up to 24 h.internalization was studied with the human grp receptor cell line pc-3.biodistribution study was performed in mice.results: radiochemical purities of > 98% was obtained. radiopeptide showedhigh stability in serum. radioligand internalization into pc-3 cells was high andspecific. biodistribution study demonstrated that 99mtc-hynic peptide clearedfast from blood and most non-targeted tissues and was excreted mainly by renalpathway and was uptake significantly in grpr positive tissues such as pancreas.conclusion: easy radiolabeling of peptide conjugate together with favorable invitro and in vivo characteristics might be a useful peptide radiopharmaceutical indiagnosis of grpr positive tumors.