Circulating MicroRNAs as Biomarkers for Papillary Thyroid Cancer: Preliminary Study

Abstract

Objectives: MicroRNAs can function either as tumor suppressors or oncogenes, and some miRNAs are associated with papillary thyroid cancer (PTC), such as miR-146b, miR-155, miR-221, and miR-222. We tried to detect miRNAs in serum and analyzed correlation between expression level. Methods: Serum was obtained from patients who underwent thyroidectomy with or without neck dissection from 2008 to 2009. Patients with benign nodule and PTC were divided. In PTC, patients were divided into 3 groups according to N stage. We investigated miRNA expression level by reverse transcription / quantitative PCR kit. It was expressed by log102(-ΔΔCT), and mean value was compared. Results: We obtained serum from 89 patients comprised of 19 benign nodules and 70 PTC. There were no differences between age or gender. MiR-146b and miR-155 were expressed −5.06 (±0.069) and −4.48 (±0.115), respectively in benign, compared to −4.79 (±0.0598) and −4.19 (±0.091) in PTC, respectively. Discriminating between benign and malignant nodule, AUC (area under the ROC curve) was 0.649 in miR-146b and 0.695 in miR-155. Although miR-155 expression of N0 group was not significantly different from that of N1, miR-155 of benign (-4.48 ± 0.115) was significantly lower than PTC with lymph node metastasis (−4.22 ± 0.097, P = 0.022). Conclusions: This study was preliminary study to detect miRNA from serum to discriminate benign group from PTC group. MiR-146b and miR-155 was increased in PTC group compared to benign. MiR-155 was increased in lymph node metastasis group compared to benign. Further study using available serum miRNA to predict recurrence or diagnosis of PTC is needed.