miR-326 inhibits the progression of papillary thyroid carcinoma by targeting MAPK1 and ERBB4.

Papillary thyroid carcinoma (PTC) is the prevalent histotype of thyroid cancer, with increasing incidence worldwide. MicroRNAs (miRNAs) could play an important role in the development and progression of human cancers. Interestingly, miR-326 was validated as one of the downregulated miRNAs in PTC. Therefore, it is necessary to research the function of miR-326 involved in the progression of PTC. In the current study, we detected the downregulation of miR-326 in PTC tissues and cell lines. The miR-326 overexpression or knockdown was conducted in TPC-1 or HTh83 PTC cells. miR-326 mimics decreased the proliferation, clone formation ability and caused G1-phase accumulation. In addition, the reduction of migration and invasion abilities was induced by miR-326 mimics. Western blot analysis showed that the cells with miR-326 mimics exhibited the inhibition of vimentin and N-cadherin, as well as enhancement of E-cadherin. Importantly, miR-326 could directly target mitogen activated protein kinase 1 (MAPK1) and epidermal growth factor receptor 4 (ERBB4). MAPK1 or ERBB4 overexpression rescued the effects of miR-326 on proliferation, migration, and invasion in PTC cells. Notably, miR-326 reduced tumorigenesis in vivo, including the decrease of tumor volume and weight, suppression of Ki-67, N-cadherin, MAPK1 and ERBB4. In all, these results might provide a new therapeutic target for the diagnosis of PTC.