Synthesis and in vivo evaluation of [11C]PJ34, a potential radiotracer for imaging the role of PARP-1 in necrosis.
Poly(ADP-ribose) polymerase-1 (PARP-1) is an abundant nuclear enzyme of eukaryotic cells that has been implicated in response to DNA injury. PARP-1 detects single-strand DNA breaks induced by a variety of genotoxic insults. A hyperactivation of PARP-1 is believed to play a critical role in tissues undergoing cellular death by necrosis. Therefore, a radiotracer that could image PARP-1 levels with PET could provide a useful tool in measuring necrosis in a variety of pathological conditions. The phenanthridinone derivative, 2-(dimethylamino)-N-(5,6-dihydro-6-oxophenanthridin-2-yl)acetamide (PJ34), has a high affinity for PARP-1 (IC(50) = 20 nM) and is a suitable lead compound for PET radiotracer development. The synthesis of [(11)C]PJ34 was accomplished by base-catalyzed reaction of the corresponding des-methyl precursor, N-(5,6-dihydro-6-oxophenanthridin-2-yl)-2-(methylamino)acetamide with [(11)C]methyl iodide in DMF. The radiolabeling yield was 60% and the specific activity was approximately 2000 mCi/micromol (decay corrected to E.O.B.). The total radiosynthesis time was approximately 50 min. Preliminary in vivo biodistribution studies in a rodent model of diabetes indicate that [(11)C]PJ34 displays a high uptake in tissues where PARP-1 is hyperactivated. These data indicate that [(11)C]PJ34 may be a useful radiotracer for imaging tissues undergoing cellular death via necrosis.
Division of Radiological Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA.
Zhude
Z
Tu
Wenhua
W
Chu
Jun
J
Zhang
Carmen S
CS
Dence
Michael J
MJ
Welch
Robert H
RH
Mach
D000818:Animals; D002250:Carbon Radioisotopes; D007150:Immunohistochemistry; D007553:Isotope Labeling; D008297:Male; D009336:Necrosis; D010179:Pancreas / Q000378:metabolism; D010616:Phenanthrenes / Q000378:metabolism*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D051381:Rats; D011920:Rats, Inbred WF; D014018:Tissue Distribution
D002250:Carbon Radioisotopes; C434926:N-(oxo-5,6-dihydrophenanthridin-2-yl)-N,N-dimethylacetamide hydrochloride; D010616:Phenanthrenes; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases