ABSTRACT
We aimed to evaluate a fluorescent-labeled single chain variable fragment (scFv) of the anti-PSMA antibody as a specific probe for the detection of prostate cancer by in vivo fluorescence imaging. An orthotopic model of prostate cancer was generated by injecting LNCaP cells into the prostate lobe. ScFvD2B, a high affinity anti-PSMA antibody fragment, was labeled using a near-infrared fluorophore to generate a specific imaging probe (X770-scFvD2B). PSMA-unrelated scFv-X770 was used as a control. Probes were injected intravenously into mice with prostate tumors and fluorescence was monitored in vivo by fluorescence molecular tomography (FMT). In vitro assays showed that X770-scFvD2B specifically bound to PSMA and was internalized in PSMA-expressing LNCaP cells. After intravenous injection, X770-scFvD2B was detected in vivo by FMT in the prostate region. On excised prostates the scFv probe co-localized with the cancer cells and was found in PSMA-expressing cells. The PSMA-unrelated scFv used as a control did not label the prostate cancer cells. Our data demonstrate that scFvD2B is a high affinity contrast agent for in vivo detection of PSMA-expressing cells in the prostate. NIR-labeled scFvD2B could thus be further developed as a clinical probe for imaging-guided targeted biopsies.
Subject(s)
Antigens, Surface/metabolism , Glutamate Carboxypeptidase II/metabolism , Prostatic Neoplasms/diagnostic imaging , Animals , Antigens, Surface/immunology , Cell Line, Tumor , Cell Tracking , Fluorescent Dyes/chemistry , Fluorescent Dyes/metabolism , Glutamate Carboxypeptidase II/immunology , Humans , Male , Mice, Inbred NOD , Mice, SCID , Neoplasm Transplantation , Optical Imaging , Prostatic Neoplasms/metabolism , Single-Chain Antibodies/chemistry , Single-Chain Antibodies/metabolism , Tomography, Emission-ComputedABSTRACT
PURPOSE: Bioluminescence imaging (BLI) is a technique with a low background noise and high sensitivity which is widely used in mice models in oncology. We aimed to assess BLI efficiency of the new luciferase NanoLuc (Nluc) for glioblastoma cell lines and tumors, including for dual reporter applications of deep brain tumors and systemic metastasis when combined with firefly luciferase (Fluc). PROCEDURES: U87 cells were genetically modified for constitutive production of either Nluc, Fluc, or both and assayed for luciferase activity and BLI on cell lysates, living cells, subcutaneous tumors, brain tumors, and systemic metastases. RESULTS: In vitro, light production by Nluc activity is higher than Fluc. In vivo, Nluc allows for tumor detection including for deep brain tumors and systemic metastases. CONCLUSIONS: Nluc appears to be a useful tool to combine with Fluc for dual imaging in vivo using bioluminescence, allowing for the detection of distinct events in deep tissues within the same organism.
