Comparative serum proteomic analysis identified afamin as a downregulated protein in papillary thyroid carcinoma patients with non-131I-avid lung metastases

BACKGROUND The loss of 131I uptake ability in metastases from differentiated thyroid carcinoma (DTC) is becoming a major obstacle in radioiodine treatment. However, there is no effective way to screen for 131I uptake ability in metastases. The identification of differentially expressed proteins by serum proteomics may contribute to our understanding of the mechanisms underlying the dedifferentiation of DTC. MATERIALS AND METHODS Serum samples were obtained from papillary thyroid carcinoma patients with non-131I-avid lung metastases and 131I-avid lung metastases. Differential protein analysis was performed using two-dimensional gel electrophoresis. Candidate protein spots showing differences in expression between the two groups were identified by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and were validated by western blotting. RESULTS We found that afamin is downregulated in the serum of papillary thyroid carcinoma patients with non-131I-avid lung metastases. CONCLUSION Afamin may be a potential serum biomarker for early screening of 131I uptake ability in DTC metastases and could therefore be of value in guiding radioiodine treatment decisions.