Reestablishment of in vitro and in vivo iodide uptake by transfection of the human sodium iodide symporter (hNIS) in a hNIS defective human thyroid carcinoma cell line

Uptake of iodide is a prerequisite for radioiodine therapy in thyroid cance r. However, loss of iodide uptake is frequently observed in metastasized th yroid cancer, which may be explained by diminished expression of the human sodium iodide symporter (hNIS). Strategies to restore iodide uptake in thyr oid cancer include the exploration of hNIS gene transfer into hNIS defectiv e thyroid cancer. In this study, we report the stable transfection of a hNI S expression vector into the hNIS defective follicular thyroid carcinoma ce ll line FTC133. Stablely transfected colonies exhibited high uptake of (NaI )-I-125, which could be blocked completely with sodiumperchlorate. hNIS mRN A expression corresponded with iodide uptake in semiquantitative polymerase chain reaction. Iodide uptake was maximal after 60 minutes, whereas iodide efflux was complete after 120 minutes, hNIS transfected FTC133 and control cell lines injected subcutaneously in nude mice formed tumors after 6 week s. Iodide uptake in the hNIS transfected tumor was much higher than in the nontransfected tumor, which corresponded with hNIS mRNA expression in tumor s.