Background: Diagnostic whole-body scan is a standard procedure in patients with thyroid cancer prior to the application of therapeutic dose of 131I. Unfortunately, administration of radioisotope in diagnostic dose may decrease further radioiodine uptake the phenomenon called thyroid stunning. We estimated radiation absorbed dose-dependent changes in genetic material, in particular in sodium iodide symporter (NIS) gene promoter, and NIS protein level in K1 cell line.
Materials and methods: We used the K1 cell line derived from the metastasis of human papillary thyroid carcinoma exposed to 131I in culture. The different 131I activities applied were calculated to result in absorbed doses of 5, 10, and 20 Gy.
Results: Radioiodine did not affect the expression of NIS gene at the mRNA level, however, we observed significant changes of the NIS protein level in K1 cells. The decrease of NIS protein level, observed in the cells subjected to the lowest absorbed dose, was paralleled by significant increase in 8-oxo-dG concentrations (P<0.01) and followed by late activation of the DNA repair pathways.
Conclusions: Our findings show that the impact of radiation on living cells, in the range compared to doses absorbed during diagnostic procedures in patients, does not show the linear dose-effect.
20 - 23 May 2017
European Society of Endocrinology