MicroRNA-520a-3p suppresses epithelial-mesenchymal transition, invasion, and migration of papillary thyroid carcinoma cells via the JAK1-mediated JAK/STAT signaling pathway.

Papillary thyroid cancer (PTC) is a kind of thyroid cancer and frequently presents with epithelial-mesenchymal transition (EMT). MicroRNAs (miRNAs) were previously reported to be associated with PTC. Thus, this study aims to define the role of microRNA-520a-3p (miR-520a-3p) in PTC through the JAK/STAT signaling pathway by targeting JAK1. The PTC and normal thyroid tissues of 137 PTC patients were collected. First of all, the expression pattern of miR-520a-3p, JAK1, JAK2, STAT3, E-cadherin, and vimentin in PTC was identified. The relationship between miR-520a-3p and JAK1 was predicted and analyzed. And a series of miR-520a-3p mimic or inhibitor, or siRNA JAK1 introduced into PTC cells were applied to examine the effect of miR-520a-3p on PTC cell viability, migration, invasion, cell cycle, apoptosis, and EMT. Meanwhile, the regulatory effect of miR-520a-3p and JAK1 on the JAK/STAT signaling pathway was also determined. The expression of JAK1, JAK2, STAT3, and vimentin increased yet miR-520a-3p and E-cadherin decreased in PTC tissue. JAK1 was negatively regulated by miR-520a-3p. Functionally, EMT induction was prevented by miR-520a-3p upregulation through downregulating JAK1. When upregulating miR-520a-3p or silencing JAK1 in PTC cells, PTC cell viability, migration, and invasion were inhibited yet cell apoptosis promoted with cells arrested at G1 phase, indicating that miR-520a-3p prevented PTC progression by downregulating JAK1. Moreover, miR-520a-3p elevation or JAK1 inhibition inactivated the JAK/STAT signaling pathway. Collectively, miR-520a-3p prevents cancer progression through inactivating the JAK/STAT signaling pathway by downregulating JAK1 in PTC.