Tc-99m-pertechnetate uptakes correlate with expressions of human sodium iodide symporter gene in breast tumor tissues

The sodium iodide symporter (hNIS), an intrinsic transmembrance protein that mediates active transport of iodine in the thyroid gland, has also been demonstrated in lactating mammary gland. We investigated the expression of hNIS mRNA in primary breast tumors and its correlation with the uptake of Tc-99m-pertechnetate (TcO4). Thirty-two consecutive patients (28 ductal, 1 papillary, 1 adenoid cystic and 1 medullary carcinoma, and 1 lactating adenoma ) underwent mammogrpahy and TcO4 scintigraphy of the breast before surgery. Both lateral images in prone position and anterior image in supine position were obtained 30 min after injection of 370 MBq of TcO4. The scintigraphy was considered to be positive when there was focal uptake that was higher than upper thoracic wall and adjacent normal breast activity. We measured the expression levels of hNIS mRNA in 32 breast tumor tissues and 14 normal tissues by noncompetitive reverse transcription-polymerase chain reaction (RT-PCR), RT-PCR values were quantified by measuring the optical density of electrophoresis bands and normalized to the GAPDH values. TcO4 scintigrpahy revealed positive uptake in 4 (2 invasive ductal, 1 papillary, and 1 lactating adenoma) out of 32 patients. There was a wide range distribution of normalized hNIS mRNA levels of breast tumors (n=32, 0.85±0.88, range 0.10-4.97) and normal breast tissue (n=14, 0.95±1.25, range 0.21-4.48 )without significant difference. However, mRNA expression of hNIS was higher in tumors with positive uptake on the scintigraphy (n=4, median 0.95, range 0.69-1.27) than that in negative uptake tumors (n=28, median 0.52, range 0.10-4.97, p<0.05). TcO4 uptake was correlated with the hNIS mRNA expressions in the breast tumor suggesting that TcO4 scintigraphy may predict hNIS mRNA expression in human breast tumor tissue