MiR-7-5pand miR-451 as diagnostic biomarkers for papillary thyroid carcinoma in formalin-fixed paraffin-embedded tissues.

MiR-7-5p and miR-451 are important members of the small RNA family, which have been shown to be significantly downregulated in various human tumors and play a key role in the occurrence and development of tumors. However, little is known about their role in endocrine malignancies. This study aimed to investigate the diagnostic value of miR-7-5p and miR-451 levels in formalin-fixed paraffin-embedded tissues of papillary thyroid carcinoma (PTC) patients, as well as the relationship between clinicopathological characteristics and the two miRNAs. Quantitative real-time PCR (qRT-PCR) was performed to detect the expression levels of miR-7-5p and miR-451 in 101 PTC tissues and in 40 nodular goiter tissues (controls). MiR-7-5p and miR-451 levels were significantly downregulated in PTC patients compared with controls (P < 0.001). MiR-7-5p expression was further downregulated in tumors with larger diameter and advanced tumor stages (all P < 0.05). Moreover, the two miRNAs showed great capability of discriminating PTC patients from controls with 89.5% (miR-7-5p) and 76.8% (miR-451) diagnostic accuracy. Furthermore, according to univariable/multivariate logistic regression, miR-7-5p was significantly associated with PTC (P < 0.001). In conclusion, MiR-7-5p and miR-451 may be used as potential diagnostic biomarkers for identification and validation of PTC patients. Moreover, miR-7-5p appears to be associated with the aggressiveness of PTC.