Serum Levels of Soluble Fas in Patients with Multinodular Goiter

Objective: Fas is a cell-surface receptor responsible for induction of apoptosis in human thyrocytes upon interaction with Fas Ligand. Fas protein expression on thyroid cells and Fas-mediated apoptosis is decreased in multinodular goiter (MNG) resulting in thyroid cell proliferation. The soluble form of Fas (sFas) produced by alternative mRNA splicing may inhibit Fas-Fas Ligand binding and apoptosis. The aim of this study was to examine whether sFas is differentially expressed in multinodular goiter (MNG), which is associated with decreased Fas-mediated apoptosis. Method: We determined serum sFas levels using enzyme-linked immunosorbent assay (ELISA) in 42 patients with MNG and 23 normal controls. Results: Serum sFas levels were increased in patients with MNG (7.47 ± 2.55 ng/ml) compared to normal controls (2.26 ± 0.9 ng/ml). Levels of sFas were not significantly correlated with age, sex or clinical parameters, such as serum levels of FT4 or TSH. Discussion: Increased sFas in MNG may indicate increased expression of alternatively spliced Fas mRNA variant and decreased expression of cell-surface Fas protein, and may enhance thyroid cell proliferation by protecting thyroid cells from Fas-mediated apoptosis.