The lncRNA XIST exhibits oncogenic properties via regulation of miR-449a and Bcl-2 in human nonsmall cell lung cancer

Long non-coding RNAs (lncRNAs) are associated with the occurrence, development and prognoses of non-small cell lung cancer (NSCLC). In the present study, we investigated the functional mechanisms of the lncRNA XIST in two human NSCLC cell lines, A549 and NCI-H1299. In all the 5 NSCLC cell lines (NL9980, NCI-H1299, NCI-H460, SPC-A-1 and A549) tested, the expression levels of XIST were significantly elevated, as compared with those in normal human bronchial epithelial cell line BEAS-2B. In A549 and NCI-H1299 cells, knockdown of XIST by siRNA significantly inhibited the cell proliferation, migration and invasion, and promoted cell apoptosis. Furthermore, XIST knockdown elevated the expression of E-cadherin, and suppressed the expression of Bcl-2. Moreover, knockdown of XIST significantly suppressed the tumor growth in NSCLC A549 xenograft mouse model. Bioinformatic analysis and luciferase reporter assays revealed that XIST was negatively regulated by miR-449a. We further identified reciprocal repression between XIST and miR- 449a, which eventually influenced the expression of Bcl-2: XIST functioned as a miRNA sponge of miR-449a, which was a negative regulator of Bcl-2. These data show that expression of the lncRNA XIST is associated with an increased growth rate and metastatic potential in NSCLC A549 and NCI-H1299 cells partially through miR-449a, and suggest that XIST may be a potential prognostic factor and therapeutic target for patients with NSCLC.