title: Identification of a new prostate-specific cyclic peptide with the bacterial FliTrx system.
abstract: Peptides are useful tools for directing radioisotopes into tumors. We evaluated the ability of a bacterial peptide display system to isolate new prostate tumor-specific peptides.
  
  
  METHODS
  We used the bacterial FliTrx system to identify a new cyclic peptide that binds to prostate carcinoma. Serum stability and binding affinities of the (125)I-labeled peptide were tested. Furthermore, the (131)I-labeled peptide was used to evaluate its biodistribution.
  
  
  RESULTS
  Several peptides showing a potential consensus motif were identified. The new peptide MM-2 is stable in serum for up to 24 h. It binds to PC-3 cells, and this binding can be inhibited more than 70% with the unlabeled peptide. Binding to human umbilical vein endothelial cells (HUVECs) and PNT-2 cells is weaker, and competition (27%) in HUVECs is less efficient. The biodistribution showed moderate accumulation in tumor.
  
  
  CONCLUSIONS
  Bacterial peptide display, an alternative to phage peptide display, can allow the identification of specific binding and stable peptides.
authors.affiliation: Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany. s.zitzmann@dkfz.de
authors.forename: Sabine
authors.initials: S
authors.lastname: Zitzmann
authors.forename: Susanne
authors.initials: S
authors.lastname: Krämer
authors.forename: Walter
authors.initials: W
authors.lastname: Mier
authors.forename: Miriam
authors.initials: M
authors.lastname: Mahmut
authors.forename: Julian
authors.initials: J
authors.lastname: Fleig
authors.forename: Annette
authors.initials: A
authors.lastname: Altmann
authors.forename: Michael
authors.initials: M
authors.lastname: Eisenhut
authors.forename: Uwe
authors.initials: U
authors.lastname: Haberkorn
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D042783:Endothelial Cells / Q000000981:diagnostic imaging* / Q000378:metabolism*; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D051379:Mice; D008807:Mice, Inbred BALB C; D009928:Organ Specificity; D010456:Peptides, Cyclic / Q000493:pharmacokinetics*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D011933:Reagent Kits, Diagnostic; D014018:Tissue Distribution
chemical_list: D010456:Peptides, Cyclic; D019275:Radiopharmaceuticals; D011933:Reagent Kits, Diagnostic