Characterization of a novel four-miRNA signature in papillary thyroid carcinoma: Integrating molecular profiling, hormonal regulation, and diagnostic implications in populations with rising PTC incidence

Diagnosing papillary thyroid carcinoma (PTC) remains challenging, particularly due to limitations in fine-needle aspiration biopsy (FNAB), which yields up to 10% nondiagnostic results. The objective of this study was to evaluate the diagnostic and prognostic potential of four candidate microRNAs (miR-21, miR-31, miR-187-3p, and miR-200a-5p) in PTC from multinodular goiter (MNG) and normal. Fresh tissue samples from PTC and MNG patients were analyzed using quantitative RT-PCR, followed by ROC analysis to assess diagnostic accuracy and correlation with clinical, histopathological, and hormonal parameters. Compared to normal tissue, miR-21 and miR-187-3p were significantly upregulated in PTC, while miR-31 and miR-200a-5p were downregulated. MNG samples showed similar but less pronounced trends. All four miRNAs differed significantly between PTC and MNG. ROC analysis revealed strong diagnostic performance, particularly for miR-187-3p (AUC = 0.937) and miR-21 (AUC = 0.914), with their combination achieving an AUC of 0.968. Expression levels correlated with age, tumor stage, surgical status, and thyroid hormones (TSH, ATG, TG), highlighting novel regulatory patterns. This miRNA panel offers promising diagnostic value and insight into PTC pathogenesis, suggesting potential for non-invasive diagnostics and targeted therapies.