title: Imaging targeted at tumor with (188)Re-labeled VEGF(189) exon 6-encoded peptide and effects of the transfecting truncated KDR gene in tumor-bearing nude mice.
abstract: BACKGROUND
  Planar imaging of (188)Re-labeled vascular endothelial growth factor (VEGF)(189) exon 6-encoded peptide (QKRKRKKSRYKS) with single photon emission computed tomography (SPECT) in tumor-bearing nude mice and effects of the transfecting truncated KDR gene on its imaging were investigated, so as to provide a basis for further applying the peptide to tumor-targeted radionuclide treatment.
  
  
  METHODS
  QKRKRKKSRYKS, coupling with mercaptoacetyltriglycine (MAG(3)) chelator was labeled with (188)Re; then in vivo distribution, planar imaging with SPECT and blocking experiment in tumor-bearing nude mice were analyzed. Recombinant adenovirus vectors carrying the truncated KDR gene were constructed to transfect tumor tissues to evaluate the effects of truncated KDR on the in vivo distribution and tumor planar imaging of (188)Re-MAG(3)-QKRKRKKSRYKS in tumor-bearing nude mice.
  
  
  RESULTS
  The labeled peptide exhibited a sound receptor binding activity. Planar imaging with SPECT demonstrated significant radioactivity accumulation in tumor 1 h after injection of the labeled peptide and disappearance of radioactivity 3 h later. Significant radioactivity accumulation was also observed in the liver, intestines and kidneys but was not obvious in other tissues. An hour after injection of the labeled peptide, the percentage of the injected radioactive dose per gram (%ID/g) of tumor and tumor/contralateral muscle tissues ratio were 1.98+/-0.38 and 2.53+/-0.33, respectively, and increased to 3.08+/-0.84 and 3.61+/-0.59 in the group transfected with the truncated KDR gene, respectively, and radioactivity accumulation in tumor with planar imaging also increased significantly in the transfection group.
  
  
  CONCLUSIONS
  (188)Re-MAG(3)-QKRKRKKSRYKS can accumulate in tumor tissues, which could be increased by the transfection of truncated KDR gene. This study provides a basis for further applying the peptide to tumor targeted radionuclide imaging and treatment.
authors.affiliation: Department of Nuclear Medicine, Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Zhe-xue
authors.initials: ZX
authors.lastname: Qin
authors.forename: Qian-wei
authors.initials: QW
authors.lastname: Li
authors.forename: Guang-yuan
authors.initials: GY
authors.lastname: Liu
authors.forename: Chao-xue
authors.initials: CX
authors.lastname: Luo
authors.forename: Gan-feng
authors.initials: GF
authors.lastname: Xie
authors.forename: Lei
authors.initials: L
authors.lastname: Zheng
authors.forename: Ding-de
authors.initials: DD
authors.lastname: Huang
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D005091:Exons; D017353:Gene Deletion; D005822:Genetic Vectors / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000235:genetics / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D011817:Rabbits; D011868:Radioisotopes / Q000493:pharmacokinetics; D012211:Rhenium / Q000737:chemistry* / Q000493:pharmacokinetics; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism* / Q000493:pharmacokinetics; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D009842:Oligopeptides; D011868:Radioisotopes; D042461:Vascular Endothelial Growth Factor A; D012211:Rhenium; D040301:Vascular Endothelial Growth Factor Receptor-2