Investigation of the alterations in miRNA expression levels in thyroid nodules and malignancies.

The relationship between preoperative miR-146b and miR-155 expression levels and postoperative pathology results in patients operated on for nodular thyroid disease and thyroid malignancy was investigated. Sixty three patients who were operated on for thyroid nodules diagnosed as benign, malignant and atypia of undetermined significance (AUS) were included in the study. Preoperative miR-146b and miR-155 expression levels of these patients were compared according to postoperative pathology results. Twenty three of the patients were male (36.5%) and 40 patients were female (63.5%). According to the results of fine needle aspiration biopsy (FNAB) taken from the patients in the preoperative period, The number of benign patients was 26 (41.2%), the number of malignant patients was 17 (26.9%), the number of patients reported as suspicion of malignancy was 10 (15.8%), and the number of AUS patients reported was 10 (15.8%). The postoperative pathology of 58.7% (n = 37) of the patients was benign, and the postoperative pathology of 41.3% (n = 26) was malignant. Compared to the group with benign postoperative pathology results, miR-146b expression level significantly increased by 8.08-fold in the group with malignant postoperative pathology results (p < 0.01). Additionally, miR-146b expression level was significantly upregulated by 3.23-fold in AUS patients compared with benign pathology results (p < 0.01). Although a 1.88-fold increase in miR-155 expression level was detected in malignant patients compared to the benign group, it was determined that the expression level of miR-155 significantly increased by 2.36-fold in AUS patients (p < 0.001). Circulating miRNA could discriminate between patients with benign and malignant nodules. Our results suggest that both miR-146b and miR-155 expression levels increased in the group with malignant postoperative pathology results. Additionally, increased miR-155 expression level could be associated with AUS progression. Therefore, miRNAs could be used as preoperative malignancy biomarkers to determine the characteristics of nodules and the decision to undergo surgery.