Overexpression of miR‑199b‑5p inhibits Ewing's sarcoma cell lines by targeting CCNL1.

MicroRNAs (miRNAs) are known to regulate the expression of a variety of genes, which are important in the development of several types of tumor, including Ewing's sarcoma (ES), at the post‑transcriptional level. Although previous studies have identified that the expression of miRNA‑199b‑5p was downregulated in various types of tumor, the expression levels of miR‑199b‑5p in ES cells remain to be elucidated. The mechanism underlying ES via the miRNA pathway remains to be elucidated. The present study demonstrated that miR‑199b‑5p was an important regulator in ES cells and its expression was downregulated in ES originated A673/TC252 cells. The ES cell lines, A673 and TC252, were transfected with an miR‑199b‑5p mimic to overexpress the levels of this miRNA. This forced expression of miR‑199b‑5p suppressed the cell proliferation and invasion, arrested cell cycle progression, and promoted cell apoptosis. Furthermore, CCNL1 was identified by bioinformatic software as a potential target gene of miR‑199b‑5p. Following this, the present study identified CCNL1 as a direct target of miR‑199b‑5p in ES cells. Taken together, the present study established a functional link between ES, miR‑199b‑5p and CCNL1, and suggested that miR‑199b‑5p acts as a tumor suppressor and may be of diagnostic and therapeutic importance for human ES.