MicroRNAs: circulating biomarkers in the follow-up of patients with papillary thyroid carcinoma

Abstract

Clinical follow-up of patients with papillary thyroid carcinoma (PTC) includes periodic dosage of serum thyroglobulin (Tg) and neck ultrasound. Patients submitted to partial thyroidectomies or not treated with I131 may have persistent Tg despite no tumor recurrence. In addition, the presence of anti-Tg may interfere in the dosage of Tg by immunometric assays, making it necessary to develop alternative methods for follow-up. MicroRNAs are small stable, cell-type specific RNA molecules differently expressed in tumors compared to normal tissues. Genomic analysis of PTCs observed specific tumor microRNAs expression profiles related to differentiation and aggressiveness. The microRNAs can be detected in plasma. Therefore, they could be used as circulating biomarkers to diagnose recurrence and to predict the prognosis of metastatic disease. This study aims to identify detectable microRNAs in peripheral blood that correlate with treatment response and progression of metastatic disease. The microRNAs will be extracted from plasma of 150 patients submitted to thyroidectomy due to PTC. The evaluation of microRNA expression will be done by qRT-PCR. An expression profile of circulating microRNAs in metastatic PTC will be determined by TaqMan Advanced miRNA Human A and B Cards assay (754 miRNAs) by comparing 9 metastatic PTC samples and PTC pools without evidence of disease. A panel of 16 microRNAs, overexpressed in the previous phase, will be designed to evaluate patients with different responses to therapy, including those with persistent anti-Tg. Results will be related to clinical data, Tg levels and clinical outcome. (AU)