The translocator protein ligand [¹⁸F]DPA-714 images glioma and activated microglia in vivo

Eur J Nucl Med Mol Imaging. 2012 May;39(5):811-23. doi: 10.1007/s00259-011-2041-4. Epub 2012 Jan 21.


Purpose: In recent years there has been an increase in the development of radioligands targeting the 18-kDa translocator protein (TSPO). TSPO expression is well documented in activated microglia and serves as a biomarker for imaging neuroinflammation. In addition, TSPO has also been reported to be overexpressed in a number of cancer cell lines and human tumours including glioma. Here we investigated the use of [(18)F]DPA-714, a new TSPO positron emission tomography (PET) radioligand to image glioma in vivo.

Methods: We studied the uptake of [(18)F]DPA-714 in three different rat strains implanted with 9L rat glioma cells: Fischer (F), Wistar (W) and Sprague Dawley (SD) rats. Dynamic [(18)F]DPA-714 PET imaging, kinetic modelling of PET data and in vivo displacement studies using unlabelled DPA-714 and PK11195 were performed. Validation of TSPO expression in 9L glioma cell lines and intracranial 9L gliomas were investigated using Western blotting and immunohistochemistry of brain tissue sections.

Results: All rats showed significant [(18)F]DPA-714 PET accumulation at the site of 9L tumour implantation compared to the contralateral brain hemisphere with a difference in uptake among the three strains (F > W > SD). The radiotracer showed high specificity for TSPO as demonstrated by the significant reduction of [(18)F]DPA-714 binding in the tumour after administration of unlabelled DPA-714 or PK11195. TSPO expression was confirmed by Western blotting in 9L cells in vitro and by immunohistochemistry ex vivo.

Conclusion: The TSPO radioligand [(18)F]DPA-714 can be used for PET imaging of intracranial 9L glioma in different rat strains. This preclinical study demonstrates the feasibility of employing [(18)F]DPA-714 as an alternative radiotracer to image human glioma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport
  • Cell Line, Tumor
  • Fluorine Radioisotopes
  • Gene Expression Regulation, Neoplastic
  • Glioma / diagnostic imaging*
  • Glioma / metabolism
  • Kinetics
  • Ligands
  • Mice
  • Microglia / diagnostic imaging*
  • Microglia / metabolism
  • Positron-Emission Tomography
  • Pyrazoles / metabolism*
  • Pyrimidines / metabolism*
  • Rats
  • Receptors, GABA / metabolism*
  • Substrate Specificity


  • Fluorine Radioisotopes
  • Ligands
  • N,N-diethyl-2-(2-(4-(2-fluoroethoxy)phenyl)-5,7-dimethylpyrazolo(1,5-a)pyrimidin-3-yl)acetamide
  • Pyrazoles
  • Pyrimidines
  • Receptors, GABA
  • TSPO protein, human