Hydrocortisone and Purinergic Signaling Stimulate Sodium/Iodide Symporter (NIS)-Mediated Iodide Transport in Breast Cancer Cells

The sodium/iodide symporter (NIS) mediates a re-markably effective targeted radioiodide therapy in thyroid cancer; this approach is an emerging can-didate for treating other cancers that express NIS, whether endogenously or by exogenous gene transfer. Thus far, the only extrathyroidal malig-nancy known to express functional NIS endog-enously is breast cancer. Therapeutic efficacy in thyroid cancer requires that radioiodide uptake be maximized in tumor cells by manipulating well-known regulatory factors of NIS expression in thy-roid cells, such as TSH, which stimulates NIS ex-pression via cAMP. Similarly, therapeutic efficacy in breast cancer will likely depend on manipulating NIS regulation in mammary cells, which differ