Sodium/iodide symporter is expressed in the majority of seminomas and embryonal testicular carcinomas

Testicular cancer is the most frequent cancer in young men. The large majority of patients has a good prognosis, but in a small group of tumours the current treatments are not effective. Radioiodine is routinely used in the treatment of thyroid cancer and is currently investigated as a potential therapeutic tool even for extra-thyroid tumours able to concentrate this radioisotope. Expression of Na+/I- symporter (NIS), the glycoprotein responsible for iodide transport, has been demonstrated in normal testicular tissue. In this study, we analyzed NIS expression in a large series of testicular carcinomas. Our retrospective series included 107 patients operated for testicular tumours: 98 typical seminomas, 6 embryonal carcinomas, 1 mixed embryonal-choriocarcinoma and 2 Leydig cells tumours. Expression and regulation of NIS mRNA and protein levels were also investigated in human embryonal testicular carcinoma cells (NTERA) by real time RT-PCR and western blotting respectively. Immunohistochemical analysis showed presence of NIS in the large majority of seminomas (90/98) and embryonal carcinomas (5/7) of the testis, but not in Leydig cell carcinomas. Expression of NIS protein was significantly associated to the lymphovascular invasion. In NTERA cells treated with the histone deacetylase inhibitors SAHA and valproic acid, a significant increase of NIS mRNA (about 60 and 30 fold vs control, p<0.001 and p<0.01 respectively) and protein levels, resulting in enhanced ability to uptake radioiodine, was observed. Finally, NIS expression in testicular tumours with the more aggressive behavior is of interest for the potential use of targeting NIS to deliver radioiodine in malignant cells.