title: Exploration of peptide T7 and its derivative as integrin αvβ3-targeted imaging agents.
abstract: OBJECTIVE
  The aim of the present study was to develop potential candidates of integrin αvβ3-targeted imaging agent, which can facilitate the diagnosis and treatment of malignant solid tumors.
  
  
  METHODS
  Peptides derived from tumstatin, named T7 and T7-6H, were derivatized to contain histidine in the C-terminus of their sequence and were labeled with (99m)Tc via nitrido and carbonyl precursors. The radiochemical purity and stability of (99m)Tc-labeled T7 and T7-6H were characterized by thin-layer chromatography. The whole body biodistribution was studied in NCI-H157-bearing BALB/c nude mice.
  
  
  RESULTS
  The (99m)Tc-labeled T7 and T7-6H showed adequate in vitro stability, with a high radiochemical purity of over 90%. The dissociation constant (Kd) value of the (99m)Tc-labeled T7 and T7-6H ranged from 68.5 nM to 140.8 nM in U251 and NCI-H157 cell lines. (99m)Tc-labeled T7 and T7-6H showed no significant difference of biodistribution in mice. Furthermore, both T7 and T7-6H exhibited a poor blood-brain barrier penetration and a transient accumulation in lung; the uptake in tumor tissues was significantly higher than in muscle tissue, with a ratio of 5.8.
  
  
  CONCLUSIONS
  (99m)Tc-labeled T7 and T7-6H can be regarded as promising single-photon emission computed tomography probes for imaging integrin αvβ3, and need to be further studied for noninvasive detection of tumors.
authors.affiliation: Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Tianjin, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: He
authors.affiliation: Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Tianjin, People's Republic of China ; Department of Reproductive Medicine, The Affiliated Hospital of Hebei University, Baoding, Hebei, People's Republic of China.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Hao
authors.affiliation: Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Tianjin, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Long
authors.affiliation: Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Tianjin, People's Republic of China.
authors.forename: Naling
authors.initials: N
authors.lastname: Song
authors.affiliation: Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Tianjin, People's Republic of China.
authors.forename: Saijun
authors.initials: S
authors.lastname: Fan
authors.affiliation: Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Tianjin, People's Republic of China.
authors.forename: Aimin
authors.initials: A
authors.lastname: Meng
keywords: angiogenesis; integrin; ligands