title: Radiolabeling LyP-1 peptide and preliminary biodistribution evaluation in mice bearing MDA-MB-435 xenografts.
abstract: BACKGROUND
  Recent studies have shown the LyP-1 peptide can home to either tumor lymphatics or the tumor cells and be internalized by targeted cells. This study aimed to investigate the possibility of using Na(131)I labeled LyP-1 peptide as an imaging agent or a therapeutic radiopharmaceutical in breast carcinoma and its metastasis.
  
  
  METHODS
  The 10-mer cyclic peptide contained the LyP-1 sequence (YCGNKRTRGC) was synthesized by the solid phase method. Disulfide bonds between the cysteines maintain the cyclic structure. The LyP-1 peptide was labeled with Na(131)I using the chloramine-T method. The [(131)I] LyP-1 peptide and a [(131)I] control peptide were injected via tail vein into nude mice bearing MDA-MB-435 tumor xenografts. Biodistribution and imaging results in vivo were obtained.
  
  
  RESULTS
  The labeling efficiencies of LyP-1 peptide reached 80% ± 5% (n = 5). The radiochemical purity was about 96%. The radiochemical purity of the labeled compound remains 92% at 24 hours in human serum at 37°C. In the biodistribution studies, the [(131)I] LyP-1 peptide accumulated in the tumor to a higher level than in other organs. The [(131)I] LyP-1 peptide can successfully image the tumor in nude mice bearing MDA-MB-435 tumor xenografts.
  
  
  CONCLUSIONS
  The LyP-1 peptide could be effectively labeled with Na(131)I and the labeled compound is stable in human serum at 37°C for 24 hours. The high specificity of [(131)I] LyP-1 peptide suggests it may be a promising new radiotracer for identifying tumors.
authors: Department of Nuclear Medicine, Clinical Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, China. ymmcyh@yahoo.com.cn
authors: Ming-ming
authors: MM
authors: Yu
authors: Rong-fu
authors: RF
authors: Wang
authors: Yue-hua
authors: YH
authors: Chen
authors: Hai-zhong
authors: HZ
authors: Zhou
authors: Xiao-hu
authors: XH
authors: Deng
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000175:diagnosis; D045744:Cell Line, Tumor; D005260:Female; D064593:Heterografts; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D010456:Peptides, Cyclic / Q000737:chemistry*; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: C533969:LyP-1 peptide; D010456:Peptides, Cyclic