Ricerc@Sapienza

Abstract
Background: Oxidative stress is responsible for some alterations in the chemical structure and, consequently, in
the function of proteins, lipids, and DNA. Recent studies have linked oxidative stress to cancers, particularly thyroid
cancer, but the mechanisms remain unclear. Here, we further characterize the role of oxidative stress in thyroid cancer
by analyzing the expression of two selenium antioxidant molecules, glutathione peroxidase (GPx1) and thioredoxin
reductase (TrxR1) in thyroid cancer cells.
Methods: Samples of both healthy thyroid tissue and thyroid tumor were taken for analysis after total thyroidectomy.
The expression of GPx1 and TrxR1 was revealed by Western blot analysis and quantified by densitometric analyses,
while the evaluation of free radicals was performed by Electron Paramagnetic Resonance (EPR)-spin trapping
technique.
Results: Our results show a decrease in the expression of GPx1 and TrxR1 (− 45.7 and − 43.2% respectively, p in the thyroid cancer cells compared to the healthy cells. In addition, the EPR technique shows an increase of free
radicals in tumor tissue, significantly higher than that found in healthy thyroid tissue (+ 116.3%, p Conclusions: Our findings underscore the relationship between thyroid cancer and oxidative stress, showing the
imbalance of the oxidant/antioxidant system in thyroid cancer tissue. These results suggest that either the inability to
produce adequate antioxidant defense or an increased consumption of antioxidants, due to the hyper-production of
free radicals, may play a crucial role in thyroid cancer.
Keywords: Oxidative stress, Thyroid cancer, Glutathione peroxidase (GPx1), Thioredoxin reductases (TrxR1), Selenium
enzymes