Targeted fluorescent imaging of a novel FITC-labeled PSMA ligand in prostate cancer

In this study, we synthesized a novel fluorescein isothiocyanate (FITC)-labeled prostate-specific membrane antigen (PSMA) ligand (PSMA-FITC) via the Fmoc solid-phase synthesis method, and the application value of PSMA-FITC in targeted fluorescence imaging of PSMA-positive prostate cancer was evaluated. The PSMA ligand developed based on the Glu-urea-Lys structure was linked to FITC by aminocaproic acid (Ahx) to obtain PSMA-FITC. The new probe was evaluated in vitro and in vivo. Fluorescence microscopy examination of PSMA-FITC in PSMA(+) LNCaP cells, PSMA(-) PC3 cells, and blocked LNCaP cells showed that the binding of PSMA-FITC with PSMA was target-specific. For in vivo optical imaging, PSMA-FITC exhibited rapid 22Rv1 tumor targeting within 30 min of injection, and the highest tumor-background ratio (TBR) was observed 60 min after injection. The TBR was 3.45 ± 0.31 in the nonblocking group and 0.44 ± 0.13 in the blocking group, which was consistent with the in vitro results. PSMA-FITC is a promising probe and has important reference value for the development of PSMA fluorescent probes. In the future, it can be applied to obtain accurate tumor images for radical prostatectomy.