The activity of nuclear factor-κB (NF-κB), a nuclear transcription factor, influences both critical tumor promotion and host-tumor interactions. Preventing NF-κB activation may thus inhibit the development of cancer. Therefore, development of easy and rapid methods to evaluate the regulation of NF-κB is needed for drug discovery. The aim of this study was to visualize the regulation of NF-κB by real-time, noninvasive bioluminescence and microPET imaging in vivo. Materials and Methods: A highly responsive HepG2/NF-κB/luc clone L for 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced tumor promotion inhibited by methotrexate (MTX) was selected by high-throughput bioluminescent imaging (BLI) in vitro. BLI and microPET using 18F-fluorodeoxyglucose (FDG) imaging were performed in HepG2/NF-κB/Luc/L hepatoma-bearing SCID mice. Results: The luciferase expression by BLI assay reflected that the TPA-induced NF-κB activity was suppressed by MTX after 16 h treatment. A positive correlation between in vitro and in vivo MTX-suppressed TPA-induced NF-κB activity was indicated. MicroPET imaging could not demonstrate any decrease in FDG uptake during the early stage at 24 h after TPA and MTX treatment. Conclusion: BLI directly revealed that MTX inhibited cellular transformation by suppressing NF-κB activity. Molecular imaging would accelerate the validation of the gene regulation of tumor cells in preclinical cellular and mouse models.
