Abstract
1439
Objectives: A multimodality reporter gene imaging is being widely used for overcoming a weak point of each modality. To develop a noninvasive dual reporter gene system for nuclear imaging and optical imaging, we evaluated the feasibility of human sodium/iodide symporter (hNIS) and red fluorescent protein (DsRed2) fusion reporter gene system in human embryonic kidney cells, HEK293. Methods: We constructed hNIS/DsRed2 fusion gene by the insertion of hNIS gene into pDsRed2-N1 (Clontech) and transfected it into HEK293 cell line by Liposome. After selection with geneticin, the hNIS/DsRed2 stable transfectant (HEK293-hNIS/DsRed2) was sorted for positive DsRed2 expression using FACS. To evaluate the function of hNIS, the uptake and efflux of I-125 were measured in the transfected and parental cells. The activity of DsRed2 protein was checked by fluorescent microscopy. Also, localization of hNIS was assessed by immunofluorescent detection and its image was acquired by laser-scanning confocal microscopy. Results: HEK293-hNIS/DsRed2 cells accumulated I-125 up 240 times higher than that of parental HEK293 cells. Iodine uptake of HEK293-hNIS/DsRed2 cells was completely blocked by perchlorate. Iodide efflux from HEK293-hNIS/DsRed2 cells was slow relatively, with only 10% released during the initial 5 min, and 60% remained at 25 min. HEK293-hNIS/DsRed2 cells showed cytoplasmic red fluorescence, while parental HEK293 cells were not. Subcellular fluorescent imaging indicated the specific localization of hNIS and DsRed2 proteins to hNIS/DsRed2 transfected HEK293 cells with background levels of activity in the parental HEK293 cells. It suggested that the function of hNIS and DsRed2 was still active after fusion of hNIS and DsRed2. Conclusions: The expression of hNIS/DsRed2 fusion protein correlated among iodide uptake, hNIS expression and fluorescent activity. This suggests that hNIS/DsRed2 fusion protein can be a useful tool for non-invasive dual imaging.
- Society of Nuclear Medicine, Inc.