Targeting sodium/iodide symporter gene expression for estrogen-regulated imaging and therapy in breast cancer

Expression of the sodium iodide symporter (hNIS) has been detected in breast cancer tissue, but frequently, not at the levels necessary to mediate 131 I accumulation. Transducing the hNIS gene into breast cancer cells with adenovirus could be a tractable strategy to render breast cancer susceptible to radioiodide therapy. We constructed the replication-incompetent virus, AdSERE, in which an estrogen-responsive promoter directs the expression of hNIS. In vitro , we demonstrate that AdSERE mediates hNIS expression and iodide uptake in ER+ breast cancer cells. In vivo , we show that AdSERE-infected ER+ tumors can be imaged due to tracer accumulation; in addition, AdSERE in combination with therapeutic doses of 131 I suppresses tumor growth.