Sodium-iodide symporter (NIS) gene expression in lymph-node metastases of papillary thyroid carcinomas.
OBJECTIVE
To investigate the molecular mechanisms underlying the influence of alteration of iodine trapping on the prognosis of metastatic papillary thyroid carcinomas, focusing on the expression of the Na+/I(-) symporter (NIS).


METHODS
We evaluated the expression of the NIS gene in a series of 11 enlarged neck lymph-node metastases of papillary thyroid carcinomas, including four patients in whom an enlarged lymph node represented the first sign of the tumoral disease. Nine lymph nodes, either reactive or metastatic for non-thyroid tumors, were also investigated.


METHODS
Expression of the NIS gene was evaluated by RT-PCR in material obtained by fine-needle aspiration biopsy.


RESULTS
The NIS gene was expressed in eight (73%) of 11 differentiated thyroid cancer metastatic lymph nodes examined. Five of these metastatic lymph nodes were positive at the post-treatment total-body iodine-131 scan; in the other three, the total-body scan showed no uptake in the metastatic tissues, indicating an alteration downstream to the NIS mRNA synthesis causing the loss of iodide uptake. As expected, when the NIS mRNA expression was absent, total-body (131)I scan showed no uptake in the metastatic lymph nodes.


CONCLUSIONS
Our study demonstrates that NIS gene expression may be absent in metastatic differentiated thyroid carcinomas and that different mechanisms, other than loss of NIS transcription, may also be involved in the loss of iodide uptake in metastatic thyroid cells. Study of NIS gene expression in the metastatic lymph nodes, therefore, may provide useful information in the management of patients with thyroid carcinoma.
Arturi
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F
Cattedra di Endocrinologia, Dipartimento di Medicina Sperimentale e Clinica, Università di Catanzaro, 88100 Catanzaro, Italy.
Russo
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D
Giuffrida
D
D
Schlumberger
M
M
Filetti
S
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D002291:Carcinoma, Papillary / Q000235:genetics*; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics*; D004587:Electrophoresis, Agar Gel; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D007455:Iodine / Q000378:metabolism; D007457:Iodine Radioisotopes; D008207:Lymphatic Metastasis / Q000235:genetics*; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D008875:Middle Aged; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D027981:Symporters; D013964:Thyroid Neoplasms / Q000235:genetics*; D013972:Thyrotropin / Q000097:blood; D000099209:Sodium-Iodide Symporters
D002352:Carrier Proteins; D007455:Iodine; D007457:Iodine Radioisotopes; D008565:Membrane Proteins; D012333:RNA, Messenger; D027981:Symporters; D013972:Thyrotropin; D000099209:Sodium-Iodide Symporters