title: Targeting properties of peptide-modified radiolabeled liposomal nanoparticles.
abstract: Radiolabeled PEGylated liposomal nanoparticles (NPs) open new possibilities for a variety of applications including diagnosis, drug delivery, targeted therapy, and monitoring treatment effects. Here we describe the characterization of liposomal NPs (liposomes and micelles) derivatized with the somatostatin analogue tyrosine-3-octreotide as a proof of concept for tumor targeting. NPs were radiolabeled with indium-111, and targeting properties were evaluated in vitro on rat pancreatic tumor cells (AR42J), demonstrating specific binding and IC(50) values in the low nanomolar range. Biodistribution studies were performed in Lewis rats and compared to single-photon emission computed tomography images. Moderate tumor uptake was found in xenografted nude mice (<2.5% ID/g tissue) as compared to control. Micelles and liposomes revealed comparable pharmacokinetics and targeting properties. This study provides insight into tumor-targeting characteristics of peptide-derivatized liposomal NPs and can serve as a basis for further improvement of these constructs.
  
  
  BACKGROUND
  The authors investigated tumor-targeting characteristics of peptide-derivatized liposomal NPs. Similar radiolabeled PEGylated liposomal NPs open new possibilities for a variety of applications including diagnosis, drug delivery, targeted therapy, and treatment monitoring.
authors.affiliation: Clinical Department of Nuclear Medicine, Innsbruck Medical University, Austria.
authors.forename: Anna
authors.initials: A
authors.lastname: Helbok
authors.forename: Christine
authors.initials: C
authors.lastname: Rangger
authors.forename: Elisabeth
authors.initials: E
authors.lastname: von Guggenberg
authors.forename: Matthias
authors.initials: M
authors.lastname: Saba-Lepek
authors.forename: Thorsten
authors.initials: T
authors.lastname: Radolf
authors.forename: Gudrun
authors.initials: G
authors.lastname: Thurner
authors.forename: Fritz
authors.initials: F
authors.lastname: Andreae
authors.forename: Ruth
authors.initials: R
authors.lastname: Prassl
authors.forename: Clemens
authors.initials: C
authors.lastname: Decristoforo
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D016503:Drug Delivery Systems; D020128:Inhibitory Concentration 50; D007496:Iridium Radioisotopes; D008081:Liposomes / Q000008:administration & dosage* / Q000737:chemistry; D051379:Mice; D008819:Mice, Nude; D008823:Micelles; D053758:Nanoparticles / Q000008:administration & dosage / Q000627:therapeutic use*; D015282:Octreotide / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D010190:Pancreatic Neoplasms / Q000188:drug therapy*; D004369:Pentetic Acid / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D051381:Rats; D011917:Rats, Inbred Lew; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon; D014183:Transplantation, Heterologous
chemical_list: D007496:Iridium Radioisotopes; D008081:Liposomes; D008823:Micelles; D010714:Phosphatidylethanolamines; C045210:3-Tyr-octreotide; D011092:Polyethylene Glycols; D004369:Pentetic Acid; D015282:Octreotide; C018525:1,2-dimyristoylphosphatidylethanolamine