Antisense-miR-21 enhances differentiation/apoptosis and reduces cancer stemness state on anaplastic thyroid cancer.

Anaplastic thyroid carcinoma (ATC) is the most aggressive malignancy in thyroid cancers. Resistance to current therapies is still a challenge. MicroRNAs are a class of small non-coding RNAs, regulating gene expression. MiR-21 is an oncomiR that is overexpressed in nearly all cancers including ATC. Accumulating evidence suggested that miR-21 has a role in cancer stemness state, apoptosis, cell cycle progression, and differentiation. Therefore, we evaluated the application of Off-miR-21 to sequester the microRNA for therapeutic purposes on ATC cell lines. In this study, C643 and SW1736 were transducted by hsa-miR-21 antagomir (Off-miR-21). PTEN gene expression was performed as a known target of miR-21. Stemness state in cancer stem cells (CSCs) was evaluated by the changes of CSC biomarkers including Oct-4 and ABCG2. Apoptosis was assessed by PDCD4 and Mcl-1 gene expression and flow cytometry. Sodium/iodide symporter ( NIS) and thyroglobulin ( TG) were measured as ATC differentiation markers. In addition, cell cycle progression was investigated via the alterations of p21 gene expression and flow cytometry. Specific downregulation of miR-21 induced the differentiation and apoptosis in C643 and SW1736. Inversely, the treatment inhibited stemness state and cell cycle progression. Knockdown of miR-21 significantly increased the expression of PDCD4, p21, NIS, and TG while leading to decreased expression of Oct-4, ABCG2, and Mcl-1.Taken together, the results suggest that miR-21, as an oncomiR, has a role not only in stemness state but also in tumor growth, differentiation, and apoptosis. Hence, suppression of miR-21 could pave the way for ATC therapy. [ABSTRACT FROM AUTHOR]