Application of ⁶⁸Ga-PSMA-617 Molecular Probe for Micro-PET Imaging of Gliomas Model

Objective To investigate the application of ⁶⁸Ga-PSMA-617 molecular probe for micro-PET imaging of gliomas tumor model.

Methods DKFZ-PSMA-617, an effective prostate specific membrane antigen (PSMA) targeted probes, was chosen to be the precursor to be radiolabelled with ⁶⁸Ga. The radio-chemical yield of ⁶⁸Ga-PSMA-617 was analyzed by Radio-TLC. Cell uptake experiments were performed on PSMA (+) LNCaP, PSMA (-) PC-3 and U87MG cells. Nude mice bearing U87MG were injected with ⁶⁸Ga-PSMA-617(7.4 MBq) via the tail vein. Micro-PET imaging was performed 5 and 40 min after the injection. Blocking studies were also performed in U87MG tumor-bearing mice after 40 min of co-injection of ⁶⁸Ga-PSMA-617 with the PSMA inhibitor (S)-2-(3-((S)-1-carboxy-3-methylbutyl)ureido) pentanedioic acid (ZJ-43) (25 mg/kg).

Results The radiotracer had a good radio-chemical yield of (99.0±1.9)% quickly tested by Radio-TLC. In cell uptake experiments, the specificity of ⁶⁸Ga-PSMA-617 was confirmed in PSMA (+) LNCaP cells and PSMA (-) PC-3 cells; meanwhile, it proved the low expression level of PSMA in gliomas U87MG cell line. From micro-PET imaging, U87MG xenografts tumors were visualized and it showed good tumor-to-background value from 1.85±0.02 (5 min) to 3.62±0.175 (40 min) which could be blocked by ZJ-43.

Conclusion ⁶⁸Ga-PSMA-617 has the potential to be used not only in prostate cancer but also in gliomas tumor model.