RAPID COMMUNICATION: Predominant Intracellular Overexpression of the Na+/I- Symporter (NIS) in a Large Sampling of Thyroid Cancer Cases

Orsolya Dohán, Zubair Baloch, Zsuzsa Bánrévi, Virginia Livolsi and Nancy Carrasco

Department of Molecular Pharmacology (O.D., N.C.), Albert Einstein College of Medicine, Bronx, New York 10461; Department of Pathology (Z.Ba., V.L.), University of Pennsylvania, Philadelphia, Pennsylvania 19104; and Department of Pathology (Z.Bá.), Faculty of Health Sciences of the Semmelweis University, Budapest, Hungary

Address correspondence to: Nancy Carrasco, M.D., Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, F-209, Bronx, New York 10461.

Abstract

Here we report the analysis of the Na+/I- symporter (NIS) protein expression in 57 thyroid cancer samples by immunohistochemistry with high-affinity anti-NIS Abs. As many as 70% of these samples exhibited increased NIS expression with respect to the normal surrounding thyroid tissue. Most significantly, NIS was located in these samples either in both the plasma membrane and intracellular compartments simultaneously, or exclusively in intracellular compartments. This suggests that NIS is clearly expressed or even overexpressed in most thyroid cancer cells, but malignant transformation in some of these cells interferes either with the proper targeting of NIS to the plasma membrane, or with the mechanisms that retain NIS in the plasma membrane after it has been targeted. The results further indicate that, in addition to indicating NIS expression in cases where it is absent (~30%), improvements in 131I radioablation therapy might result from promoting targeting of NIS to the plasma membrane in the majority (~70%) of thyroid cancers.