Combined molecular MRI and immuno-spin-trapping for in vivo detection of free radicals in orthotopic mouse GL261 gliomas.

Abstract

Free radicals play a major role in gliomas. By combining immuno-spin-trapping (IST) and molecular magnetic resonance imaging (mMRI), in vivo levels of free radicals were detected within mice bearing orthotopic GL261 gliomas. The nitrone spin trap DMPO (5,5-dimethyl pyrroline N-oxide) was administered prior to injection of an anti-DMPO probe (anti-DMPO antibody covalently bound to a bovine serum albumin (BSA)-Gd (gadolinium)-DTPA (diethylene triamine penta acetic acid)-biotin MRI contrast agent) to trap tumor-associated free radicals. mMRI detected the presence of anti-DMPO adducts by either a significant sustained increase (p<0.001) in MR signal intensity or a significant decrease (p<0.001) in T1 relaxation, measured as %T1 change. In vitro assessment of the anti-DMPO probe indicated a significant decrease (p<0.0001) in T1 relaxation in GL261 cells that were oxidatively stressed with hydrogen peroxide, compared to controls. The biotin moiety of the anti-DMPO probe was targeted with fluorescently-labeled streptavidin to locate the anti-DMPO probe in excised brain tissues. As a negative control a non-specific IgG antibody covalently bound to the albumin-Gd-DTPA-biotin construct was used. DMPO adducts were also confirmed in tumor tissue from animals administered DMPO, compared to non-tumor brain tissue. GL261 gliomas were found to have significantly increased malondialdehyde (MDA) protein adducts (p<0.001) and 3-nitrotyrosine (3-NT) (p<0.05) compared to normal mouse brain tissue, indicating increased oxidized lipids and proteins, respectively. Co-localization of the anti-DMPO probe with either 3-NT or 4-hydroxynonenal was also observed. This is the first report regarding the detection of in vivo levels of free radicals from a glioma model.

• Authors: Rheal A Towner, Nataliya Smith, Debra Saunders, Patricia Coutinho De Souza, Leah Henry, Florea Lupu, Robert Silasi-Mansat, Marilyn Ehrenshaft, Ronald P Mason, Sandra E Gomez-Mejiba, Dario C Ramirez
• Journal: Biochimica et biophysica acta (Biochim Biophys Acta) Vol. 1832 Issue 12 Pg. 2153-61 (Dec 2013) ISSN: 0006-3002 [Print] Netherlands
• PMID: 23959048 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2013.

Chemical References

• Albumins
• Contrast Media
• Cyclic N-Oxides
• Free Radicals
• Immunoglobulin G
• Nitrogen Oxides
• Spin Labels
• albumin-(gadolinium-DTPA)
• nitrones
• 3-nitrotyrosine
• Tyrosine
• 5,5-dimethyl-1-pyrroline-1-oxide
• Gadolinium DTPA

Topics

• Albumins
• Animals
• Brain Neoplasms (diagnostic imaging, metabolism, pathology)
• Contrast Media
• Cyclic N-Oxides (immunology)
• Disease Models, Animal
• Free Radicals (analysis, isolation & purification)
• Gadolinium DTPA
• Glioma (diagnostic imaging, metabolism, pathology)
• Immunoglobulin G (pharmacology)
• Magnetic Resonance Imaging
• Mice
• Mice, Inbred C57BL
• Nitrogen Oxides (metabolism)
• Oxidation-Reduction
• Radiography
• Spin Labels (chemical synthesis)
• Spin Trapping
• Tumor Cells, Cultured
• Tyrosine (analogs & derivatives, metabolism)