Decreased serum exosomal miR-29a expression and its clinical significance in papillary thyroid carcinoma

Background Aberrant levels of circulating microRNAs (miRNAs) are potential biomarkers in papillary thyroid carcinoma (PTC) diagnosis and therapy. The aim of this study was to evaluate serum exosomal miR-29a expression as a non-invasive biomarker for PTC diagnosis and prognosis. Methods Quantitative reverse transcription polymerase chain reaction was applied to measure serum exosomal miR-29a expression levels in blood samples of 119 patients with PTC and 100 control subjects. Results Serum exosomal miR-29a expression levels were significantly decreased in PTC cases. In addition, receiver operating characteristic (ROC) analysis revealed serum exosomal miR-29a could well differentiate PTC from normal controls. Moreover, serum exosomal miR-29a levels increased progressively and significantly 30 days and 90 days after surgery. Furthermore, PTC patients with lower serum exosomal miR-29a expression had higher risk of recurrence. Decreased serum exosomal miR-29a expression was significantly associated with worse clinical variables including tumor size, extrathyroidal extension, and TNM stage, as well as shorter survival. Finally, both univariate and multivariate identified serum exosomal miR-29a as an independent prognostic indicator for overall survival. Conclusion These results demonstrated that serum exosomal miR-29a might serve as a potential biomarker for PTC diagnosis and prognosis.