Downregulation of MiR-431 expression associated with lymph node metastasis and promotes cell invasion in papillary thyroid carcinoma.

Backgrounds: The purpose of this study was to investigate clinical role and functional effects of miR-431 expression in papillary thyroid carcinoma (PTC).

Methods: Expression of miR-431 in PTC patient tissue samples and plasma samples was examined by using qRT-PCR methods. Cell migration and invasion capacity were evaluated using transwell assays. Western blot analysis was performed to detect protein expression after miR-431 overexpression in PTC cells.

Results: We demonstrated that miR-431 expression was lower in PTC tissues and plasma samples compared to their corresponding controls. MiR-431 expression was particularly lower in PTC patients with lymph node (LN) metastasis. In vitro, miR-431 overexpression significantly inhibited cell migration, invasion and EMT process by upregulating E-cadherin and downregulating Vimentin expression. Additionally, wedemonstrated that miR-431 overexpression suppressed Hedgehog (Hh) signaling pathway by downregulating Gli1 expression.

Conclusion: Our results indicated that miR-431 could serve as a predictor for PTC patients with positive lymph node metastasis and a potential target of PTC treatment.