Keywords: Contrast Agent, Gadolinium, Melanoma, Microenvironment, Redox, Tumor, 2 Pyridinedithio, Contrast Medium, Gadoteridol, Gadoteridol Pdp, N Ethylmaleimide, Thiol Derivative, Tris(2 Carboxyethyl)phosphine, Unclassified Drug, Animal Cell, Animal Experiment, Animal Model, Article, Cell Membrane, Controlled Study, Drug Uptake, In Vivo Study, Mouse, Nonhuman, Nuclear Magnetic Resonance Imaging, Oxidation Reduction Reaction, Priority Journal, Signal Transduction, Tumor Xenograft, Biological Transport, Cell Line, Coordination Complexes, Injections, Intralesional, Kinetics, Ligands, Limit Of Detection, Inbred C57bl, N-Ethylmaleimide-Sensitive Proteins, Sulfhydryl Reagents, Sulfides, Biological Transport Drug Effects, Contrast Media Administration, Dosage Chemistry Diagnostic Use, Coordination Complexes Administration, Gadolinium Administration, Experimental Diagnosis Metabolism Pathology, N-Ethylmaleimide-Sensitive Proteins Chemistry Metabolism, Pyridines Chemistry, Sulfhydryl Reagents Administration, Dosage Chemistry Diagnostic Use Pharmacology, Sulfides Chemistry Diagnostic Use, Tris (2 Carboxyethyl) Phosphine,
Affiliations: *** IBB - CNR ***
Institute for Biostructures and Bioimages (CNR), C/o Molecular Biotechnology Center (University of Turin), Via Nizza 52, I-10126 Torino, Italy
Department of Environmental and Life Sciences, Università Del Piemonte Orientale A. Avogadro, Viale T. Michel 11, I-15121 Alessandria, Italy
Department of Chemisty, IFM and Center for Molecular Imaging, University of Turin, Via Nizza 52, I-10126 Torino, Italy
References: Not available.
MR Contrast Agents
Murine melanoma B16 cells display on the extracellular side of the plasma membrane a large number of reactive protein thiols (exofacial protein thiols, EPTs). These EPTs can be chemically labeled with Gd-DO3A-PDP, a Gd(III)-based MRI contrast agent bearing a 2-pyridinedithio chemical function for the recognition of EPTs. Uptake of gadolinium up to 10(9) Gd atoms per cell can be achieved. The treatment of B16 cells ex vivo with a reducing agent such as tris(2-carboxyethyl)phosphine (TCEP) results in an increase by 850% of available EPTs and an increase by 45% of Gd uptake. Blocking EPTs with N-ethylmaleimide (NEM) caused a decrease by 84% of available EPTs and a decrease by 55% of Gd uptake. The amount of Gd taken up by B16 cells is therefore dependent upon the availability of EPTs, whose actual level in turn changes according to the extracellular redox microenvironment. Then Gd-DO3A-PDP has been assessed for the labeling of tumor cells in vivo on B16.F10 melanoma tumor-bearing mice. Gd-DO3A-PDP (or Gd-DO3A as the control) has been injected directly into the tumor region at a dose level of 0.1 mu mol and the signal enhancement in MR images followed over time. The washout kinetics of Gd-DO3A-PDP from tumor is very slow if compared to that of control Gd-DO3A, and 48 h post injection, the gadolinium-enhancement is still clearly visible. Therefore, B16 cells can be labeled ex vivo as well as in vivo according to a common EPTs-dependent route, provided that high levels of the thiol reactive probe can be delivered to the tumor.