Enhanced Effect of Iodide - Uptake in Thyroid Carcinoma Cells by Infecting Adenovirus - Human Sodium Iodide Symporter (Ad - hNIS) / 대한내분비학회지

ABSTRACT

BACKGROUND: The sodium-iodide-symporter (NIS) is a plasma membrane glycoprotein with 13 putative transmembrane domains, which is responsible for concentrating iodide into the thyroid by an active transport and provides the mechanism for radioactive-iodine (RAI) therapy for thyroid cancer. However, undifferentiated thyroid cancers and about 2050% of differentiated thyroid cancers do not take up the RAI at therapeutic dose. The NIS has been cloned from rat and human (hNIS) and characterized recently. In an attempt to develop a new therapeutic strategy using hNIS gene for improving the efficacy of RAI therapy in thyroid cancers, we have constructed a recombinant adenovirus encoding the hNIS (Ad-hNIS) and tested its function by an iodide uptake by infecting human thyroid cancer cells. METHODS: RT-PCR was performed to measure an intrinsic hNIS expression in thyroid cancer cell lines, such as NPA, FRO and ARO. To generate the hNIS adenovirus, hNIS cDNA was isolated and ligated into Swa I site of cosmid shuttle vector (pAxCAwt). We have produced recombinant adenovirus by co-transfecting the cosmid with DNA-TPC to 293 cell line. Adenovirus that express (beta-Galactosidase (LacZ) was also prepared by the similar strategy. Adenovirus infection efficiency was measured in three thyroid cancer cell lines. Finally, 24 hours after infection of ad-hNIS into the cells, I125-uptake was measured. RESULTS: Endogenous hNIS expression was detected only in FRO cells but not in NPA, ARO and Hela cells by RT-PCR. X-Gal staining after infection of Ad-LacZ to thyroid cancer cell (NPA, ARO, FRO) showed that an infection rate in ARO cells was 98.5+0.5%, 97.0+0.2% in FRO cells and 75.5+5.0% in NPA cells. We selected ARO cells for the infection of Ad-hNIS due to the highest infection efficiency and the absence of endogenous hNIS expression. When ARO cells were infected with the ad-hNIS, I125 uptake was increased 504+6.4%. CONCLUSION: Overexpression of hNIS gene in thyroid cancer cells elicited over 5 fold increase in I-uptake, suggesting that the Ad-hNIS infection to the thyroid cancer cells may improve the efficiency of radioactive iodine therapy.