Long Noncoding RNA E2F4as Promotes Progression and Predicts Patient Prognosis in Human Ovarian Cancer

SIMPLE SUMMARY: LncRNA is a promising biomarker that predicts the prognosis of a variety of cancers, but the important role of E2F4antisense lncRNA in cancer remains unclear. Therefore, we decided to explore the role of E2F4as lncRNA in the blood of an ovarian cancer patient. We found that E2F4as was highly expressed in ovarian cancer patients, and that the higher the expression of E2F4as, the worse the patient’s prognosis. In addition, we observed that downregulation of E2F4as in ovarian cancer cells reduced cell proliferation, invasion and migration, decreased expression of EMT-related genes, and increased apoptosis. These findings suggest that E2F4as may be a predictive biomarker in the blood of ovarian cancer patients, and have shown the potential to promote tumor aggression through EMT-related mechanisms. ABSTRACT: (1) Background: LncRNAs could be a promising biomarker to predict the prognosis of various cancers. The significance of E2F4antisense lncRNA remains unclear in cancer. In this study, we examined the expression level of E2F4as in the serum of ovarian cancer patients and the functional role of E2F4as. (2) Methods: Serum samples were obtained from 108 OC patients and 32 normal patients to measure the expression of E2F4as in the serum. Ovarian cancer cells were used to investigate the role of E2F4as in cell proliferation, invasion, migration and apoptosis, and the expression of E2F4as was knocked down using RNA interference. In addition, E2F4as knockdown cell lines were used in in vivo experiments. (3) Results: The expression of E2F4as was significantly higher in the serum of OC patients than in that of control patients (p < 0.05). The knockdown of E2F4as in ovarian cancer cells led to a decrease in cell proliferation, invasion and migration and an increase in apoptosis. E2F4as knockdown also reduced the expression of epithelium–mesenchymal metastasis (EMT) genes. (4) Conclusion: These findings highlight the clinical significance of E2F4as in predicting the prognosis of OC patients and suggest its potential in promoting tumour aggressiveness by the regulation of EMT-related mechanisms.