Nancy Carrasco’s main area of interest is transport across biological membranes, particularly by the sodium/iodide symporter (NIS), the key plasma membrane protein that mediates active iodide uptake in the thyroid. Carrasco’s group cloned NIS and has made great strides in characterizing it at the molecular level. NIS is at the center of the treatment for thyroid cancer based on administering radioiodide post-thyroidectomy, the most effective targeted internal radiation cancer therapy ever devised.
Carrasco’s group has discovered that functional NIS is endogenously expressed in breast cancer, opening up the possibility that this disease too could be treated with radioiodide.
Carrasco’s group has investigated the function and regulation of NIS in extrathyroidal tissues and in cancer to extend the clinical use of NIS beyond thyroid disease. They have obtained key structure/function information on NIS and identified amino acid residues that play crucial roles in substrate binding, translocation, specificity, and stoichiometry, and in targeting NIS to the cell surface. They are currently using these findings to optimize NIS molecules for use as reporter and therapeutic molecules in gene transfer studies.
Carrasco’s group has demonstrated that NIS transports different anion substrates with different stoichiometries, and is working to elucidate the structural basis for this versatility. They have also shown that NIS actively transports the anion perchlorate, an environmental pollutant. This suggests that the health effects of exposure to perchlorate are more serious than previously thought.