Long Noncoding RNA KCNQ1OT1 Accelerates the Progression of Ovarian Cancer via MicroRNA-212-3/LCN2 Axis

Long noncoding RNA KCNQ1OT1 (KCNQ1OT1) has been identified to be deregulated in several kinds of cancers. However, its expression pattern and functions in ovarian cancer remain unknown. Bioinformatics analysis showed that miR-212-3p, an identified suppressor in ovarian cancer, was a direct target of KCNQ1OT1, suggesting that KCNQ1OT1 may play a role in ovarian cancer progression via targeting miR-212-3p. Here we aimed to explore the effect of KCNQ1OT1 on the carcinogenesis of ovarian cancer, as well as to investigate miR-212-3p roles in this process. The expression of KCNQ1OT1 and miR-212-3p in ovarian cancer tissues and cells was detected by qPCR. MTT, flow cytometry, wound healing, Transwell chambers, and in vivo tumor formation assays were carried out to assess cell proliferation, apoptosis, migration, invasion, and tumorigenesis, respectively. RNA pulldown and luciferase gene reporter assays were used to evaluate the RNA–RNA interaction. The results showed that KCNQ1OT1 was overexpressed in ovarian cancer tissues and cells, which closely associated with the advanced clinic process and poor prognosis in ovarian cancer patients. Upregulation of KCNQ1OT1 significantly enhanced cell growth, migration, and invasion and inhibited cell apoptosis via miR-212-3p. In addition, we identified that lipocalin2 (LCN2) was a direct target of miR-212-3p and functioned as an oncogene to promote cell growth and to inhibit cell apoptosis. Furthermore, we observed that KCNQ1OT1 overexpression significantly enhanced the tumorigenesis of SKOV3 cells, whereas this effect was significantly impaired when LCN2 expression was downregulated. Overall, the present study reveals that KCNQ1OT1 functions as an oncogene in ovarian cancer via targeting miR-212-3p/LCN2 axis, which might provide new markers and targets for ovarian cancer diagnosis and treatment.