MON-LB82 Plasma Expression Level of MiRNA -21 Is Related With the Presence of Papillary Thyroid Cancer

Abstract Introduction.: There is no effective and reliable biomarker to distinguish benign thyroid nodules (BTN) from papillary thyroid carcinomas (PTC). In this study we analyzed a set of four miRNA molecules in plasma of patients with papillary thyroid cancer, benign nodules and healthy controls to identify miRNA molecules that may be markers of PTC.Aim.: We aimed to investigate the dysregulation of plasma miRNAs in PTC and evaluate the diagnostic value for differentiation of PTC from BTN. Methods.: The expression levels of 4 miRNAs (miR-221, miR-222, miR-146b, miR-21) were measured in 48 PTC patients before thyroidectomy and again after thyroidectomy in a subgroup of 36 patients. Preoperative and postoperative plasma miRNA expression levels were compared with baseline levels established in plasma from the heathy controls group (N=57) and patients with BTN (N=22). MicroRNA-222 and miR-146b, miR-221, miR-21 were included in a panel because they all reportedly were overexpressed in PTC compared to benign nodules or normal thyroid tissue.Results.: Compared with baseline levels in the healthy controls group, miR-221, miR-222, miR-146b, miR-21 levels were significantly higher in the preoperative PTC group (P <0.0001, P=0.002, P=0.028, P =0.021, respectively). A significant reduction in miR-21 expression was observed in postoperative PTC patients. MiR-21 decreased by 5.98-fold (P=0.046) in post- operative samples compared with preoperative samples in the PTC patients.In comparison MiRNRs expression levels in BTN group with healthy controls, miR-221, miR-21 expression levels were significantly higher in the BTN group (P=0.003, P=0.048, respectively). No significant difference was observed between the preoperative PTC group and the preoperative BTN group with regard to the expression of these four miRNA’s. Conclusions: The expression levels of miR-222, miR-146b in plasma were significantly higher in patients who had PTC than in healthy volunteers, whereas levels of miR-221, miR-21 in plasma were significantly higher in patients who had either PTC or BTN before thyroidectomy than in healthy volunteers. Furthermore, miR-21 showed a significant reduction of expression levels after thyroidectomy in PTC patients. However, value of these four miRNAs is still limited in differential diagnosis of PTC and benign nodules.