Endocrine Abstracts

Irisin is a recently reported, widely discussed new adipo-myokin secreted mainly by muscle tissue. It is a cleaved and secreted part of fibronectin type III domain containing 5, encoded by the FNDC5 gene. Some of the previously published studies claim that alterations of irisin levels in patients affected by thyroid diseases may be connected mainly with accompanying myopathy. However, to date it has not been evaluated, whether the changes in expression of FNDC5 may play a role in irisin level alterations. The aim of the presented study is to assess the expression of FNDC5 gene in thyroid tissue of subjects with Graves’ disease, multinodular benign goiter, toxic goiter and papillary thyroid cancer. The group of 80 patients with above mentioned thyroid pathologies were involved. All included subjects underwent total thyroidectomy for reasons unrelated to the study. Quantitative RT-PCR was used to analyze the FNDC5 gene expression. As a result, the expression of FNDC5 was noted in all analyzed samples. No statistical difference between FNDC5 expression in benign and malignant changes, as well as conditions associated with hyperthyroidism and euthyroid state were found. Statistically significant overexpression of FNDC5 in patients with toxic goiter in comparison with tissues affected by Graves’ disease, papillary thyroid cancer (tumor staged pT1 or pT2) and controls was observed. In conclusion, toxic goiter may be associated with FNDC5 overexpression in thyroid tissue, in comparison with Graves’ disease, papillary thyroid cancer staged pT1 or pT2 and controls. The FNDC5 overexpression, on the other hand, is not directly associated with hyperthyroid state, as well as thyroid malignancy development. Hence, the changes in FNDC5 expression probably do not play the role in irisin concentration changes associated with thyroid pathologies.