Radioiodide Imaging and Treatment of ARO Cancer Xenograft in a Mouse Model after Expression of Human Sodium Iodide Symporter

Abstract

Background: Most undifferentiated and anaplastic thyroid carcinomas are not sensitive to ¹³¹I therapy due to their lost ability for iodide accumulation. This study aims to restore the iodide uptake by transferring and expressing human sodium iodide symporter (hNIS) in these cancer cells for ¹³¹I gene therapy. Materials and Methods: hNIS cDNA expression vector was transfected into wild-type anaplastic thyroid cancer cells (ARO-W) which do not concentrate iodide. Stable trasfected cells were isolated (ARO-S) and analyzed by RT-PCR, radioiodide uptake and immunocyto-chemistry staining. ¹³¹I imaging and treatment were performed on mice bearing ARO-W and ARO-S xenograft tumors and tumor volume was recorded. Results: The ARO-S cells showed clear hNIS expression on the cell membrane and accumulated 87-fold and 4.4-fold radioiodide of that of wild-type cells in vitro and in vivo, respectively. Radioiodide uptake was dependent on cell number and reached a maximum level at 20 minutes in vitro. The half life of radioiodide efflux was 12 minutes and 12 hours in vitro and in vivo, respectively. Administration of a therapeutic dose of ¹³¹I into mice bearing ARO-S tumors effectively inhibited tumor growth as compared to control mice. Conclusion: Our results suggest the potential of hNIS-mediated ¹³¹I gene therapy on anaplastic thyroid cancer cells.