Evaluation of Anti-cancer Efficacy of Potassium Usnate using NIR Imaging of Orthotopic Breast Cancer Mouse Model

Mouse cancer models are useful tools for evaluating in vivo tumor growth and metastasis, providing valuable information for preclinical testing. In this process, optical imaging enables the mouse models to easily identify the progress of disease in a non-invasive way. Here, we established an experimental bioimaging animal model of near-infrared (NIR) fluorescence by using a fluorescence-labeled organism bioimaging instrument (FOBI) and evaluated the anti-cancer effect of potassium usnate (KU) in an orthotopic breast cancer model. The cell viability assay revealed that KU had cytotoxicity with half maximal inhibitory concentration of approximately 138.57, 167.69, and 144.17 μM in 4T1-Fluc-Neo/iRFP-Puro (4T1-iRFP), MDA-MB-231, and MCF-7 cells, respectively. The measurement of NIR fluorescence from the 4T1-iRFP cells in a microtube via FOBI exhibited a strong correlation between cell number and fluorescence intensity, and the minimal detection limit was 10⁵ cells. Accordingly, NIR imaging was performed on the orthotopic breast cancer mouse model by using FOBI, and regression of tumor progression through intraperitoneal KU administration was successfully monitored. Our results demonstrated the establishment of NIR imaging in the orthotopic breast cancer animal model for evaluating the anti-cancer effect of KU.