Clinical significance of miR-34a expression in thyroid diseases – an 18F-FDG PET-CT study

Purpose To evaluate the possible roles of miR-34a expression in thyroid lesions, to unravel the correlation between fluorodeoxyglucose (FDG) uptake and miR-34a expression and moreover, to discover the underlying mechanisms by which miR-34a regulates FDG avidity. Methods We retrospectively reviewed 75 patients with pathology-confirmed thyroid diseases who underwent 18F-FDG positron emission tomography/computed tomography (PET/CT) within 3 months before undergoing thyroid surgery and miR-34a analysis from June 2012 to July 2017. 18F-FDG uptake of thyroid lesions was also analyzed semiquantitatively using maximum standardized uptake value (SUVmax). The association between miR-34a expression and clinicopathological variables (age, sex, TNM stage, histopathology, lesion numbers, location and 18F-FDG avidity) was investigated. When there were multiple lesions in thyroid bed, only the one with the highest 18F-FDG uptake was analyzed. Next, we inhibited the miR-34a expression in TPC-1 cells and detected the expression of glucose transporter 1 (GLUT1) mRNA and protein. Results In the patients cohort, miR-34a was upregulated in those with malignant thyroid diseases compared with benign lesions. The expression of miR-34a was associated with tumor stages, histopathological types and SUVmax. There was an inverse relationship between miR-34a expression and SUVmax in patients with thyroid diseases (Spearman correlation coefficient = -0.553, P < 0.0001). With an SUVmax of 4.3 as the threshold, sensitivity and specificity of the prediction of miR-34a expression (low or high) were 70% and 94.3%, respectively. The area under the receiver operating characteristic curve was 0.843 (95% confidence interval: 0.749, 0.936; P = 0.001). Inhibiting miR-34a in TPC-1 cells significantly increased GLUT1 mRNA and protein expression. Conclusion miR-34a expression was upregulated in thyroid lesions, negatively correlated with SUVmax and can be predicted by FDG SUVmax. In addition, miR-34a may regulate FDG avidity via targeting GLUT1.