Solute carrier family 5 member 5 (SLC5A5) (NIS)

The Sodium Iodide Symporter (NIS), encoded by the SLC5A5 gene, is a transmembrane glycoprotein that mediates the active transport of iodide into cells using the electrochemical sodium gradient [1]. While naturally expressed in the thyroid gland for hormone biosynthesis, its expression in 'infected' tumor cells is a specialized therapeutic strategy achieved through gene therapy or oncolytic virotherapy [2]. By delivering the NIS gene to non-thyroidal cancer cells, these cells are engineered to concentrate radioactive isotopes such as Iodine-131, which facilitates targeted cell destruction through localized beta-emission [3]. This approach serves as a theranostic platform, allowing for both high-resolution diagnostic imaging (using I-123, I-124, or Tc-99m) and targeted radiotherapy [4]. The primary clinical challenge involves ensuring sufficient and uniform NIS expression within the tumor to achieve a therapeutic radiation dose while minimizing off-target effects in endogenous NIS-expressing tissues like the salivary glands and gastric mucosa [2, 5].

Other names

Sodium/iodide symporterNa(+)/I(-) symporterSLC5A5Sodium-iodide symporter

Mediates the active transport of iodide ions into the cytoplasm via a 2Na+/1I- symport mechanism, utilizing the sodium gradient maintained by Na+/K+-ATPase. In the context of infected tumor cells, it enables the selective intracellular accumulation of therapeutic radionuclides to induce DNA damage and apoptosis [1, 3].