Detection of the prodrug-activating enzyme carboxypeptidase G2 activity with chemical exchange saturation transfer magnetic resonance.

Yann Jamin, Thomas R Eykyn, Evon Poon, Caroline J Springer, Simon P Robinson

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose
The purpose of this study is to evaluate if the differential exchange rates with bulk water between amine and amide protons can be exploited using chemical exchange saturation transfer magnetic resonance (CEST-MR) to monitor the release of glutamate induced by carboxypeptidase G2 (CPG2), an enzyme utilized in cancer gene therapy.

Procedures
Z spectra of solutions of the CPG2 substrate, 3,5-difluorobenzoyl-L-glutamate (amide), and glutamate (amine) were acquired at 11.7 T, 37 °C, across different pH (5–8). The ability of CEST-MR to monitor CPG2-mediated release of glutamate was assessed in extracts of CPG2-expressing cancer cells and purified solution of CPG2.

Results
The addition of CPG2 to a solution containing 3,5-difluorobenzoyl-L-glutamate led to a marked and progressively increasing CEST effect (+3 ppm), concomitant with the time-dependent release of glutamate induced by CPG2.

Conclusion
CEST-MR allows the detection of CPG2 activity in vitro and supports the translation of CEST-MRI to assess CPG2-based gene therapy in vivo.
Original languageEnglish
Pages (from-to)152-157
Number of pages6
JournalMolecular Imaging and Biology
Volume16
Issue number2
DOIs
Publication statusPublished - 17 Aug 2013

Research Beacons, Institutes and Platforms

  • Manchester Cancer Research Centre

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