Abstract
BACKGROUND: Recent studies suggest that long noncoding RNAs (lncRNAs) play an important role in tumorigenesis. As a newly identified lncRNA, the role of XIST in colorectal cancer (CRC) has not been established. Here, we sought to characterize the role of XIST and its associated regulatory network in CRC cells. METHODS: Expression of XIST mRNA, miR-497-5p, and forkhead box k1 (FOXK1) in CRC cells and tissues were detected using quantitative real-time polymerase chain reaction (qRT-PCR). Proliferation and apoptosis of CRC cells were determined using the CCK-8 cell counting assay and flow cytometry. The rate of cell migration and invasion was determined using a transwell assay. The relationships between XIST, miR-497-5p, and FOXK1 were predicted and confirmed using a dual-luciferase reporter assay. Expression of FOXK1 protein was quantified by Western blot. RESULTS: XIST and FOXK1 expression were significantly upregulated in CRC tissues and cell lines, while miR-497-5p expression was downregulated. XIST knockdown significantly suppressed CRC cell proliferation, migration, and invasion. Silencing of XIST also reversed the downregulation of miR-497-5p and upregulation of FOXK1. Moreover, blocking XIST expression was shown to inhibit CRC tumor growth in vivo and the effects were antagonized by the loss of miR-497-5p. miR-497-5p was shown to act as a sponge of XIST and also targeted FOXK1 in CRC cells. CONCLUSIONS: XIST was shown to promote the malignancy of CRC cells by competitively binding to miR-497-5p, resulting in an increase in FOXK1 expression. These results suggest that targeting of XIST may represent a possible treatment for CRC.