title: Modification of cyclic NGR tumor neovasculature-homing motif sequence to human plasminogen kringle 5 improves inhibition of tumor growth.
abstract: BACKGROUND
  Blood vessels in tumors express higher level of aminopeptidase N (APN) than normal tissues. Evidence suggests that the CNGRC motif is an APN ligand which targets tumor vasculature. Increased expression of APN in tumor vascular endothelium, therefore, offers an opportunity for targeted delivery of NGR peptide-linked drugs to tumors.
  
  
  RESULTS
  To determine whether an additional cyclic CNGRC sequence could improve endothelial cell homing and antitumor effect, human plasminogen kringle 5 (hPK5) was modified genetically to introduce a CNGRC motif (NGR-hPK5) and was subsequently expressed in yeast. The biological activity of NGR-hPK5 was assessed and compared with that of wild-type hPK5, in vitro and in vivo. NGR-hPK5 showed more potent antiangiogenic activity than wild-type hPK5: the former had a stronger inhibitory effect on proliferation, migration and cord formation of vascular endothelial cells, and produced a stronger antiangiogenic response in the CAM assay. To evaluate the tumor-targeting ability, both wild-type hPK5 and NGR-hPK5 were (99 m)Tc-labeled, for tracking biodistribution in the in vivo tumor model. By planar imaging and biodistribution analyses of major organs, NGR-hPK5 was found localized to tumor tissues at a higher level than wild-type hPK5 (approximately 3-fold). Finally, the effects of wild-type hPK5 and NGR-modified hPK5 on tumor growth were investigated in two tumor model systems. NGR modification improved tumor localization and, as a consequence, effectively inhibited the growth of mouse Lewis lung carcinoma (LLC) and human colorectal adenocarcinoma (Colo 205) cells in tumor-bearing mice.
  
  
  CONCLUSIONS
  These studies indicated that the addition of an APN targeting peptide NGR sequence could improve the ability of hPK5 to inhibit angiogenesis and tumor growth.
authors.affiliation: The State Key Laboratory of Pharmaceutical Biotechnology and School of Stomatology, Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Jiang
authors.forename: Guanghui
authors.initials: G
authors.lastname: Jin
authors.forename: Dingyuan
authors.initials: D
authors.lastname: Ma
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Tong
authors.initials: T
authors.lastname: Fu
authors.forename: Xiao
authors.initials: X
authors.lastname: Chen
authors.forename: Xiwen
authors.initials: X
authors.lastname: Chen
authors.forename: Kunzhi
authors.initials: K
authors.lastname: Jia
authors.forename: Faiz M M T
authors.initials: FM
authors.lastname: Marikar
authors.forename: Zichun
authors.initials: Z
authors.lastname: Hua
mesh_terms: D020816:Amino Acid Motifs; D020533:Angiogenesis Inhibitors / Q000493:pharmacokinetics* / Q000494:pharmacology; D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D002642:Chick Embryo; D005260:Female; D006801:Humans; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009842:Oligopeptides / Q000235:genetics / Q000493:pharmacokinetics* / Q000494:pharmacology; D010446:Peptide Fragments / Q000235:genetics / Q000493:pharmacokinetics* / Q000494:pharmacology; D010958:Plasminogen / Q000235:genetics / Q000493:pharmacokinetics* / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000493:pharmacokinetics / Q000494:pharmacology
chemical_list: D020533:Angiogenesis Inhibitors; C526428:NGR peptide; D009842:Oligopeptides; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C491499:plasminogen kringle 5; D010958:Plasminogen