Paramagnetic resonance in detecting carcinogenic risk from cytochrome P450 overexpression.
BACKGROUND
Despite the increasing interest in the role of oxygen radicals on human degenerative disorders including cancer, oxidative stress status is not yet measurable in vivo, largely precluding clinical application. Limited semi-quantitative assays of damage to broad classes of biomolecules such as lipids, proteins, and DNA are currently available. The detection of radicals in humans by a whole-body electron paramagnetic resonance (EPR) technique has not yet been developed, although this possibility has long fascinated free radical investigators.


METHODS
While the EPR spin trapping procedure can be used to detect carbon centered or hydroxyl radical in human tissues, the most common spin traps are much less useful for capturing the superoxide anion (O2). To overcome these limitations, we propose a whole-body-harvest approach that utilizes a highly lipophilic spin scavenger that when injected in the animal is capable of trapping the O2 generated in vivo throughout the body with formation of a stable nitroxide measurable by EPR in the urine. A process known to generate the O2 is the induction of certain cytochrome P450 (CYP) isozymes by drugs or environmental pollutants.


RESULTS
We report: 1) a correlation between the induction of each CYP gene family and the O2 yield; 2) support to an observation reported previously that the tumor promoting ability of CYP inducers is mainly mediated by the O2; and 3) the description of a method for nitroxide mediated O2 detection in vivo.


CONCLUSIONS
These findings could open the way for using electron spin resonance in diagnostic practice.
Paolini
M
M
Department of Pharmacology, Medical School, University of Bologna, Italy.
Pozzetti
L
L
Pedulli
G F
GF
Cipollone
M
M
Mesirca
R
R
Cantelli-Forti
G
G
D000818:Animals; D002478:Cells, Cultured; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D004790:Enzyme Induction; D008297:Male; D051379:Mice; D008862:Microsomes, Liver / Q000201:enzymology; D018384:Oxidative Stress; D013481:Superoxides / Q000032:analysis
D013481:Superoxides; D003577:Cytochrome P-450 Enzyme System