Regulation of iodide uptake and sodium/iodide symporter expression in the MCF-7 human breast cancer cell line

Sodium/iodide symporter (NIS) expression has recently been described in human breast cancer, with emphasis on its potential exploitation for the treatment of these tumors with radioiodine. In this study, we analyzed the regulation of NIS expression and function in the MCF-7 human breast cancer cell line. Cell exposure to insulin, IGF-I, IGF-II, or prolactin induced significant increases in 125I uptake and the expression of both NIS mRNA and NIS protein. The latter increases were evident after 6 and 12 h of hormonal stimulation, respectively. In immunocytochemistry studies, NIS was detected mainly in the plasma membrane of MCF-7 cells. A low but significant increase in iodide uptake was produced by treatment with activators of the adenylyl cyclase (cAMP) or protein kinase C pathways. Our study demonstrates that: 1) MCF-7 breast cancer cells are capable of active iodide transport that can be stimulated by insulin, IGF-I, IGF-II, or prolactin; 2) both NIS transcript and protein are expressed in these cells, ...