%0 Journal Article %A Chung-Li Ho %A Liang-Cheng Chen %A Wan-Chi Lee %A Shu-Pei Chiu %A Wei-Chuan Hsu %A Wuu-Jyh Lin %A Meei-Ling Jan %A Chih-Hsien Chang %A Te-Wei Lee %T Receptor-binding, biodistribution and micro-SPECT/CT imaging of 111In-DTPA-Bombesin analogue in human prostate tumor-bearing mice %D 2009 %J Journal of Nuclear Medicine %P 1597-1597 %V 50 %N supplement 2 %X 1597 Objectives Gastrin-releasing peptide receptors (GRPR) are overexpressed on a variety of human tumors like prostate, breast, and lung cancer. Bombesin (BN) is a 14 amino acid peptide with high affinity for these GRPRs. We synthesized DTPA-Q-K-Y-G-N-Q-W-A-V-G-H-L-M, a 13 amino acid peptide chelated with diethylenetriaminepentaacetic acid (DTPA), and radiolabeled this BN analogue with 111InCl3. Biological activity of 111In-DTPA-BN was evaluated in PC-3 prostate tumor-bearing SCID mice. Methods A solid phase approach was used to synthesize DTPA-BN. The affinity of DTPA-BN to BN type 2 receptor was determined by a competitive displacement cell-binding assay using 125I-Tyr4-BN. MicroSPECT/CT and biodistribution were performed after iv injection of 111In-DTPA-BN. Results The purity of synthesized DTPA-BN was greater than 95%. The radiochemical purity of 111In-DTPA-BN was 96.9% ± 2.46%. The IC50 and Ki of DTPA-BN in the human bombesin 2 receptor were 1.05 ± 0.46 nM and 0.83 ± 0.36 nM, respectively. Both biodistribution and micro-SPECT/CT imaging studies with 111In-DTPA-BN demonstrated the highest uptake at 8 hour post-injection. The Pearson correlation analysis showed a positive correlation of tumor uptake between biodistribution and micro-SPECT/CT semi-quantification imaging analysis (r=0.832). Conclusions Our result revealed111In-DTPA-BN has high affinity with BN type 2 receptor. The results demonstrated a good uptake in the GRPR-over expression PC-3 tumor-bearing SCID mice. 111In-DTPA-BN is a potential agent for imaging GRPR-positive tumors in humans. %U