LINC00115 promotes stemness and inhibits apoptosis of ovarian cancer stem cells by upregulating SOX9 and inhibiting the Wnt/β-catenin pathway through competitively binding to microRNA-30a

OBJECTIVE: Long non-coding RNAs (lncRNAs) and microRNAs (miRs) are differentially expressed in ovarian cancer (OC) cells and influence OC progression. This study intended to explore the underlying roles of LINC00115 and miR-30a in OC. METHODS: Gene Expression Omnibus database was used to find OC microarray datasets and bioinformatics analysis predicted the potential molecular mechanism of OC. OC stem cells (OCSCs) surface marker was isolated from human OC cell line and identified. CD133(+) OCSCs were transfected with LINC00115, miR-30a and SOX9 alone or together to detect sphere-forming ability and apoptosis of OCSCs. Caspase-3 activity and DNA damage in cell supernatant were detected. The levels of CD44, NANOG, POU5F1, LINC00115, CD133, miR-30a and SOX9 were measured. Then sh-LNC00115-treated OCSCs were added with Wnt/β-catenin activator SKL2001 to observe the changes of cell stemness and activity. Finally, animal models were established to evaluate the effect of LINC00115 on OCSC in vivo. RESULTS: LINC00115 and SOX9 were highly expressed in OC, while miR-30a was lowly expressed. After silencing LINC00115 or overexpressing miR-30a, the sphere-forming rate of CD133(+) OCSC and levels of CD133, CD44, NANOG and POU5F1 decreased, while apoptotic rate, Caspase-3 activity and histone-related DNA damage increased. SOX9 reversed these trends. Additionally, LINC00115 could bind to miR-30a and miR-30a could target SOX9. SKL2001 partially reversed cell stemness and activity in sh-LNC00115-treated OCSCs. Finally, silencing LINC00115 could inhibit OCSCs growth in vivo. CONCLUSION: LINC00115 promoted stemness and inhibited apoptosis of OCSCs by upregulating SOX9 and in activating the Wnt/β-catenin pathway through competitively binding to miR-30a.