The function of membrane-localized
sodium iodide symporter (NIS) determines the efficacy of radioiodine
therapy in
thyroid cancer. Here, we describe a dual mode reporter fused with human NIS (hNIS) and a
red fluorescent protein named tandem dimeric Tomato (
tdTomato) for the in vitro and in vivo imaging of hNIS
protein expression, localization, and
iodide uptake function. Human cervical epithelial
adenocarcinoma cell line (HeLa)-hNIS/
tdTomato cells were established by transducing a fusion gene expressing hNIS/
tdTomato under the control of a cytomegalovirus promoter. Fluorescence imaging, confocal microscopy, and an 125I uptake assay were performed to validate the integrity of the fusion
protein.
Actinomycin D and
cycloheximide were used to block newly synthesized hNIS
proteins. In vivo images were acquired using a
gamma camera and a Maestro fluorescence imaging device. The fluorescence intensity of membrane-localized hNIS and 125I uptake both were increased after heat shock. Scintigraphy and fluorescence imaging indicated specific accumulation of the hNIS/
tdTomato fusion
protein in xenografted
tumors, supporting the utility of this system for in vivo monitoring of hNIS expression and activity. We developed a novel hNIS/
tdTomato dual mode reporter that enables visualization of the expression, localization, and
iodine uptake function of hNIS in vitro and in vivo.